protecting residences from wildfires: a guide for homeowners, lawmakers, and planners

8/8/2019 Protecting residences from wildfires: a guide for homeowners, lawmakers, and planners

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United StatesDepartmentdAgriculture

Forest Service

Protecting Residences Fmmires:a guide for homeowners,

Pacific SouthwestForestend RangeExperiment Station

awmakers, and pGeneral TechnicalReport PSW-50 I-loward E. Moore


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Author:HOWARD E. MOORE was Deputy State Forester of the California Departmentof Forestry before his retirement in 1974. He is now a fire protection consultant atDavis, Calif. He earned a B.S. degree in forestry (1948) at the University ofCalifornia, Berkeley, and an M.A. degree in government (1974) at California StateUniversity, Sacramento. He joined the California Department of Forestry in1948. This report was prepared for the Station under contract 40-9AD6-8-1083.

Publisher:Pacific Southwest Forest and Range Experiment StationP.O. Box 245, Berkeley, California 94701


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1 Moore, Howard E. II 1981. Protecting residences from wildfires: a guide for homeowners, lawmakers,and planners. Gen. Tech. Rep. PSW-50, 44 p., illus. Pacific Southwest Forest I1 and Range Exp. S tn., Forest Serv., U.S. ep. A gric., Berkeley, Calif. II This guide, based on a l i terature review and personal co ntacts, offers recom-

mendations and standards for procedures in reducing losses of residences from II wildfires. Possible solutions to the problem of fire protection are discussed in the I1 broad areas of land-use planning and zoning, property development, structuraldesign and constrution , landscaping, accessories, occup ant activit ies, and finan- II cia1 incentives. The problem of reducing fire losses in undeveloped areas is also I1 discussed and solutions propose d. Th e guide is intended for homeowners, law-makers, and members of the building, planning, and financial communities. II I

I Retrietgnl Terms: fire prevention (structures), fire hazard reduction, water supply(residential), urban-wildland fire interface, insurance, cons truction m aterials I1 (buildings) I1 I


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Protecting Residences From Wia guide for homeowners. awmakers.Howard E . Moore

CONTENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ecommendations 1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ature of the Problem 5

Residential Developments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Fire Hazards and Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Fire Suppression Difficulty. Costs. and Limitations . . . . . . . . . . 8Floods and Erosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ack of Single Solution 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .and-Use Planning and Zoning 11Fire Hazard Severity Classification . . . . . . . . . . . . . . . . . . . . . . . . . 11General and Specific Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Zoning Ordinances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Spacing and Building Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Property Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Water Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Perimeter Protection and Fire Access . . . . . . . . . . . . . . . . . . . . . . 16Electric Power Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Street Names and Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Fire Station Sites . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . 18Structural Design an d Con struction . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Roofing . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. 19Vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Overhangs and Stilt Construction . . . . . . . . . . . . . . . . . . . . . . . . . . 20Glass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Siding . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . 21External Sprinklers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Safety of Human Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Mobile Homes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Landscaping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Native Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Plantings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Irrigation and Sprinkling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Herbicides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Fire-Retardant Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27


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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .aintenance 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .oofs and Rain Gutters 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ards 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .torage 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ccessories 31. . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . .. .wimming Pools 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ences 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .utbuildings 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .atios. Sun Decks. Balconies 32Water Pumps . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . 33

FuelTanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Occupant Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Advance Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Preparations for Possible Emergency . . . . . . . . . . . . . . . . . . . . . . . 35Wildfire Approaching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .inancial Incentives 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .nsurance Surcharges 36LoanTerms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Tax Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37. . . . . . . . . . . . . . . . . . . .ndeveloped Areas: An Additional Problem 38Fuels Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39Legislation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40. . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . .ire Defense Systems 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ire Alert Systems 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iterature Cited 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .lossary 44


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e Zone for its relative fire hazard severity all land,whether in a city or unincorporated area, that is notalready developed for residential, commercial, indus-trial, or cultivated agricultural use, in addition toland-use or other zoning.

e Require by law that general and specific plans containan evaluation of fire protection problems and a de-lineation of the means to cope with them.

o Require all cities and counties having any areas ofundeveloped wildlands within their boundaries to re-view their ordinances on planning, land use, building,and fire for the purpose of making them truly effectivein reducing the danger of destruction of residencesand other structures by wildland fire.

@ Impose standards of building spacing and density forwildfire hazardous areas by local ordinances. Basesuch standards on a classification system related tovegetative fuels, topography, and known weatherpatterns.

@ Prior to development of any project intended forhuman occupancy in wildland areas-whether thedevelopment be conventional subdivision, plannedunit, cluster, lot split, commercial, or industrial-provide two or more access routes adequate to allowtwo-way travel over roads that are not blocked by thefire or the results of the fire (e.g., fallen trees or pow-erlines, vehicle wrecks).

@ Authorize permit-granting agencies to require devel-opers, before they build any structures in wildlands,

to provide adequate water supplies and the means ofdelivering them to protect such structures.

e Incorporate perimeter protection from wildland firesinto the design of every new subdivision and mobilehome park developed in wildland areas.

@ Install electric power distribution circuits under-ground in wildland areas.@ Mark every road at each intersection and identify

every land parcel or home ;n wildfire hazardousareas, in a manner clearly visible from a public roadby names or numbers.

@ Dedicate structural fire station sites before approvingplans for any large, expensive, or high-occupant den-sity development in a wildland area.

e Require all buildings located in wildfire hazardousareas to have roofs with a fire-retardancy commensu-rate with the hazard classification.

e Cover all exterior attic and underfloor vents withscreens that are adequate to prevent the entrance offlammables and firebrands.

@ Design all homes and other structures to be located inor near wildfire hazardous areas with as few sver-hangs and projections as possible and where they areunavoidable protect them from ignition through heatand flame entrapment.

e Design, orient, manufacture, and install all glazedopenings, especially large picture windows and slid-ing glass doors, in a way that minimizes the opportu-nity for interior ignition from external sources.


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@ In all structures that may be exposed to danger fromwildland conflagrations, construct the exterior wallsusing fire-resistant material commensurate with thedegree of hazard involved.Do not install permanent roof sprinklers.

@ Design and equip all structures-especially dwellingunits-to provide occupants warning of a fire andready escape routes.

ta Design, build, and install mobile homes with thesame regard for fire safety as used in any other resi-dence.

@ Clear and bottom-prune all native vegetation (exceptfor isolated specimen plants) in chaparral and otherwildland areas for a distance from each structure ap-propriate to the fire hazard severity class and slopeclass of the site.

@ Plant and maintain with fire retardant or low-fuel-volume plants all areas cleared of native vegetationfor fire protection purposes, if such areas are notmaintained free of flammables (e.g., paved areas).

e Irrigate landscaping plant5 at least until they becomewell established, but do not irrigate native vegetation.

@ Consider the use of selective herbicides to achievespecific purposes in fire protection landscaping to beboth desirable and legitimate.

e Explore the feasibility and economics of fire-retardant chemicals used on surrounding vegetation,native or planted, for home fire protection in wildfirehazardous areas.

@ Maintain roofs in a fire safe manner (i.e., clean andmade of fire-retardant materials).

@ Maintain all yards, gardens, landscaped areas, andfire protection clearances so as to retain their fire safequalities.

@ Do not store uncovered flammable materials againstthe exterior wall of any building nor close enough to itto cause ignition of the structure by radiated or con-vective heat should the materials burn.

@ Install and equip every swimming pool or othersignificant water source in wildfire hazardous areassuch that the water may be obtained quickly and eas-ily for firefighting purposes both by fire engines andby the occupant.

@ Design, construct, and maintain fences so that theydo not help wildland fires spread-especially to struc-tures.* Build and maintain outbuildings to the same stand-ards of fire safety as the residence or other mainstructure with which they are associated.

@ Design and install patios, sun decks, and balconies inways that enhance the fire safety of the building towhich they are an accessory.

@ Install private water systems in a way to provideadequate, dependable source of water for fire protec-tion purposes.

e Install storage tanks for hydrocarbon fuels so thatthey are separated from native vegetation by thesame distance required for the residence, providedwith a nonflammable heat shield, and separated fromother structures by the same distance required forstructures.

@ Prepare and test a plan for protecting property fromfire and have on hand the tools and equipment neededfor such an emergency.

@ Take special precautionary measures to protectproperty from fire during very high and extreme fireweather conditions, whether an actual fire is in prog-ress or not.

e When a wildfire becomes a threat to a home or otherstructure in or near wildlands the occupants shouldtake final protective actions and evacuate all whocannot make a positive contribution to a firefightingeffort.

e Establish fire insurance rates for structures located inor near wildfire hazardous areas to reflect the actualprobability of destruction by conflagration.

e Adjust the interest rates and other conditions for allreal estate or development loans in hazardous wildfireareas so as to encourage fire-safe design and con-struction.

e Provide tax incentives to persons who meet or ex-ceed minimum fire-safe standards, and apply taxpenalties to those who fail to conform to standards.

@ Treat and continuously manage vegetation fuels onall wildlands that may become fire threats so as toreduce the conflagration hazard and facilitate fire con-trol.

e Encourage the legislative bodies of states, counties,and cities to conduct a critical review of their lawsand regulations relating to wildland fire protectionand, on the basis of such reviews, adopt new meas-ures that will provide reasonable fire safety and re-solve conflicts of law with other public safety andenvironmental protection measures.

e Establish fire defense systems in advance on all un-developed wildlands so located as to pose a fire threatto areas developed for human use and occupancy.

ea Enlist the aid of property owners and others withvested interests in homes and other structures locatedin or near wildland areas, both as individuals andthrough their organizations and associations, in seek-ing ways to participate in and improve the Red FlagFire Alert System.


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E ch year, wildfires burn hundreds of homes andother structures in or adjacent to forests andrangelands. And even before the last flames have flick-ered out, some owners begin thinking about rebuildinghomes on the very sites scorched by fire. This situationis not new or confined to a particular area; nor are theproposed remedies new or applicable only to a particu-lar area.

Southern California epitomizes the problem of pro-tecting homes from recurring wildfires. Several condi-tions contribute to a fire protection problem that is assevere as to be found anywhere. Vegetation, rangingfrom heavy stands of grass to brush to hardwoods orconifers, thrives in the Mediterranean climate there.Other conditions contributing to the high fire hazard arethe large population, mountainous topography, and anincreasingly affluent, mobile society encroaching intowildlands.

These same conditions are found in other regions thatenjoy the Mediterranean climate-parts of Europe,Australia , Chile, and South Africa. The vegetation pro-duced and the resulting fire protection problem are notgreatly different from those found in California.

Much has been written about what can be done toremedy the problem, but few recommendations havebeen implemented. Many studies merely duplicate workdone previously. To bring all of the pertinent informa-tion together, I reviewed the extensive literature on fireprotection, and made personal contacts to obtain orconfirm sources or both.

This report summarizes information on proceduresfor reducing losses of residences and other structuresfrom wildfires. It outlines the problem of protectinghomes from such fires, and proposes recommendationsand standards. The Proposed Standards are proposalsfor the technically best solutions. Worded in advisory


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NATUREOF THE PROBLEM

Residential DevelopmentsBecause of the congestion and pollution of major met-

ropolitan areas, subdivisions, individual homes, andmobile home parks continue to proliferate year afteryear. Many are in or close to wildland fuels, subjectingthem to the danger of being burned (Harvey 1974; Hul-bert 1972; Orange County Bd. Sup. 1976; Oreg. St .Dep. For. 1978a). This development has usually pro-ceeded faster than has the enactment of effective lawsand ordinances to alleviate the problem. Because offinancial, social and political pressures, even those ef-forts previously made to require firesafe constructionand occupancy have been only partially enforced, and,therefore largely ineffective (Hulburt 1972).

Within commuting distance (40 to 60 miles) of met-ropolitan areas, development most often takes the formof relatively expensive residences on medium-to-largelots. Unless prohibited by well designed and effectivelyenforced ordinances, developers tend to leave as muchnative vegetation as possible to maintain and promotethe rural effect that the buyers seek. Similarly, devel-opers usually provide wood shingle or shake roofs, pic-ture windows, and sun decks. Water and other utilitiesare usually provided only in amounts adequate for nor-mal use unless fire codes are strictly enforced. Becauseof high land values, road rights-of-way tend to be nar-row and, if in mountainous areas, steep. In such circum-stances, residents often have only one route of ingressand egress (Orange County Bd. Sup. 1976; Los AngelesCounty 1973).

In addition to suburban subdivisions, hundreds ofthousands of residences and their outbuildings havebeen built in the past few years beyond practical com-muting range from cities. Such buildings can be found inany of several arrangements. One is the rural subdivi-sion composed of second (weekend or vacation) and/orretirement homes. Except for location and the inclusionof some recreation and light commercial development,these subdivisions appear similar and present fire prob-lems similar to those posed by suburban subdivisions.

Although fewer than those in subdivisions, the struc-tures that individually cause the greatest fire protectionproblems are ones built by or for their occupants onindividual parcels of land, each usually with its ownwater system. The most dangerous of these problemsresult from so-called lot splitting. Lot splits tend tocreate densities approaching those of subdivisionswithout any of the inherent advantages of subdivisions(e.g., access to a public thoroughfare, water system,refuse disposal, sewage system). All individually devel-oped residences, whether on large farms or small par-cels of land, are difficult to protect, from fire. Theirwater supply is seldom adequate. Access is usuallylong, narrow, and slow. Electric power, if available, issubject to interruption, often by the fire itself. /#

A relatively new structural fire problem is the mobilehome, which presents all the fire problems of the con-ventional home and several more. Because the structureitself is more susceptible to flash fire, occupants find itmore difficult to escape. If the structure is not fittedwith adequate skirting, wildfire will run quickly under


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0 10 20 30 40T ime (years)

Figure2 -Tota l fuel loading and ra ction of deadmaterial both increase as chamise ages (Philpot1974).

the floor. A mobile home is easier than a conventionalhouse to set up with little or no clearing of native vege-tation. And when it is placed in a mobile home park, thespacing between structures normally is insufficient toprevent a fire from spreading by radiation or convection(Los Angeles County Fire Dep. 1970; Org. St. Dep.For. 1978a).

Fire Hazards and R i s kFire hazards are those elements in the combustion

process that actually burn or that cause the fire to burnfaster or hotter than normal. Fire risks are those factorsthat cause fires to be ignited. To protect residences andother structures from damage by wildland fire, both firehazards and fire risks must be understood and dealtwith. Fire hazards fall into three broad categories: fuels,weather, and topography. Fuels, in turn, are composedof two types: vegetation and structures.

Composed of cellulosic materials, all vegetation isflammable to some degree. Some types (e.g., chaparral)are much more flammable than others (e.g., irrigatedlandscaping plants). All vegetation is more flammable atcertain times than at others. Vegetation in its wild stateconsists of both living and dead materials. The deadmaterials and the fine living materials (leaves or needlesand twigs) represent the bulk of the "available" wild-land fuel. Figure 2 shows how fuels increase with time.In timber stands and heavy brush fields, this available

fuel may reach 50 tons per acre. In areas of 1- to2-year-old logging slash, fuel loading may run up to 200tons per acre. When hundreds or thousands of acres ofsuch volumes of fuel are burned in short periods oftime-as often happ ens unde r conflagrationconditions-the amount of heat and energy releasedapproaches that of an atomic bomb. Flame lengths canexceed 100 feet. Radiated heat can ignite exposedflammable materials at distances of 100 or more feet.Convection columns carrying flaming leaves and otherfire brands often extend many thousands of feet into theatmosphere and have been known to drop such fire-brands several miles downwind. Thousands of homescan be exposed to these conditions (Task Force onCalifornia's Wildland Fire Probl. 1972, Helm andothers 1973, Nord and Countryman 1972).

Of particular concern is the wildland fuel known aschaparral, because so much of it is in or near metropoli-tan areas. Chaparral also represents an unusuallydangerous fire hazard because of its inherent qualities.As a "fire climax plant community," chaparral has forthousands of years not only survived repeated fires buthas adapted itself to depend on fire for regeneration andsurvival. Thus wherever chaparral exists large-scale firecan be predicted with great certainty to occur sooner orlater, and the longer between fires the larger they are( f i g . 3) . In southern California, the average time be-tween fires in any given area (cycle time) is about 30years (Hanes 1974, Nord and Countryman 1972, Phil-pot 1974, Wright 1972).

, Y e a r sFigure3 - A wildfire increases n size as the ageof cham ise increases (Philpot1974).


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Structures built in wildlands can also be hazardousfuel. They are mostly of wood frame construction, oftenwith wood siding. Wood shingle or shake roofs arecommon, particularly in suburban and rural subdivi-sions. Attic and floor vents are often left unscreened.Picture windows and stilt or cantilever balconies facingdirectly into or over heavy wildland fuels are common.Many roofs and rain gutters hold large quantities of dryleaves or needles. Dooryards often are not kept clear offlammable vegetation. Any or all of these qualities con-tribute to make these structures one of the most hazard-ous fuels in the urban, suburban, rural or wildland set-ting (Alger 1971, Task Force on California's WildlandFire Probl. 1972).

Weather, or more specifically "fire weather," canproperly be termed a fire hazard because it aids ignitionand accelerates combustion. Almost all conflagrationshave occurred during periods of extreme fire weather.We can do little about the weather except to understandit and its interactions with the other hazards. Yetweather is at least as important as fuels in the urban1wildland interface fire problem.

The weather elements responsible for very high orextreme fire danger are strong winds, high tempera-tures, low humidities, and low fuel moisture contents.This combination can happen, and has, at almost anytime of the year, including the middle of winter. In areaswith Mediterranean climates, such as most of Califor-nia, extreme fire weather is actually quite common dur-ing late summer and fall, and should be expected to bepresent one or more times at any point in the Stateduring the period from mid-June to mid-November(Alger 197 1, Task Force on California's Wildland FireProbl. 1972, Deeming and others 1977, Phillips 197 I).

By far the most critical factor in fire weather is wind.A study of fires 5000 acres or larger during the period1961-70 revealed that at the time of start of 66 fires forwhich weather records were available, the average windspeed was about 30 mph; in some it went as high as 75

Table I-Santcc Atza .fi.eq~lency nd d~r rat ionbymonth in southern California, 1951-60

MonthSeptemberOctoberNovemberDecemberJanuaryFebruaryMarchAprilMayJuneJulyAugust

Average durationFrequency

Source: Countryman (1974).

mph (Los Angeles County Fire Dep. 1970, Task Forceon California's Wildland Fire Probl. 1972).

The most dangerous wind is the foehn (subsidence)wind, the most notorious being the Santa Ana of south-ern California (table I). In other parts of the world thiswind is known by other local names, such as mono,north wind, mistral, chinook, tramontana, and williwa.The foehn wind produces the usual effects of winds:fanning and supplying oxygen, preheating fuels by bend-ing flames from the vertical, and carrying burning fire-brands ahead of the fire front. But it also brings dry airfrom continental high pressure areas, then heats anddries it further by compression as it flows to lower ele-vations at a velocity of up to 100 mph (Alger 1971,Orange County Bd. Sup. 1976, Task Force on Califor-nia's Wildland Fire Probl. 1972, Phillips 197 1).

High temperatures bring the fuels, both vegetativeand structural, closer to their ignition temperatures.Low humidities dry the moisture from the fuels. Lowfuel moistures, by reducing the amount of heat used invaporizing moisture, reduce the total amount of heatneeded to raise the fuel to ignition temperature. Evengreen fuels, particularly chaparral, can have remarkablylow moisture contents after long dry summers or underadverse fire weather conditions (Deeming and others1977, Hanes 1974, Nord and Countryman 1972, Philpot1974, Wright 1972).

The third major hazard contributing to wildland andstructural fire danger is mountainous topography. Al-though it increases the costs of construction and devel-opment, such topography attr acts thousands ofhomeowners with its feeling of openness, an attractiveview, and the possibility of getting above or away fromthe smog. Sidehill construction often makes structuresmore ignitable (e.g., stilts, cantilevers). Topography af-fects fires in some of the same ways that wind does aswell as modifying, and often intensifying, the effects ofthe wind. Generally fires run faster uphill than down.Higher elevation fuels (e.g., houses on ridgetops) arepreheated by flames and convection columns even inthe absence of wind. Canyons act as chimneys trappingheat and intensifying combustion. Canyons, saddlesand ridgelines deflect, and often intensify, winds. Thusthe mouths of canyons on the lee side of main ridgesoften become raging infernos during a Santa Ana.Roadbuilding is difficult and expensive in mountainousterrain, often making ingress for firefighting manpowerand equipment and egress for residents slow and dif-ficult.

The fire risks involved in the structural/wildland fireproblem are almost all man-caused. In the populatedportions of California, 90 percent or more of therfires

'Alger 1971, Tas k Force on California's Wildland Fire Probl. 1972,Deeming and others 1977, Hanes 1974, Helm and others 1973, LosAngeles County Fire Dep. 1970, Orange County Bd. Sup. 1976, Phil-pot 1974.


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involving vegetation are caused either by people di-rectly or by their developments (e.g., arson, varioustypes of machines, power lines); only 4.2 percent of theconflagration fires are caused by lightning. The mereacts of developing, constructing and occupying struc-tures in formerly wildland areas, therefore, expose boththe wildlands and the structures to increased risk ofdestruction by fire (Alger 1971, Task Force on Califor-nia's Wildland Fire Probl. 1972, Moore 1977).

The risk of structural ignition during wildland firescomes from any of three sources: direct exposure toflame, radiated heat, or firebrands carried by winds orconvection columns or both. The first two of thesesources can be fairly easily guarded against by properclearance of native vegetation, landscaping, and main-tenance. The last (most common) is much more com-plex and requires a combination of defenses, includingall those described in the chapters on Land-Use Plan-ning and Zoning; Property Development; StructuralDesign and Construction; Maintenance; and Unde-veloped Areas. The most usual structural fuel bed forignition by these flying firebrands, which are often car-ried from one-quarter mile to 2 miles ahead of the firefront, is the roof. Therefore, roofing materials andcleanliness are of prime importance as protective meas-ures (Alger 1971, Los Angeles County Fire Dep. 1970,Orange County Bd. Sup. 1976, Task Force on Califor-nia's Wildland Fire Probl. 1972, Helm and others 1973).

Fire Suppression DifficuityyCosts,and LimitationsThe owners of structures in or near wildland fuels

cannot depend on the fire suppression efforts of publicagencies to protect their buildings from destruction.The use of tax funds to pay for enough firefighters andequipment to contain every fire that starts on the fewdays of very high and extreme fire weather conditions isboth economically and politically infeasible. I t is, infact, also physically impossible under typical conflagra-tion conditions of very strong, hot, dry winds. There-fore, each owner or resident must assume his or hershare of the responsibility for preventive measures(Alger 1971, Los Angeles City-County Fire Bd. Inquiry1971, Green 1977, Howard and others 1973).

Firefighting is at best one of the most hazardous ac-tivities of man. Under conflagration conditions, therisks of entrapment, asphyxiation, heat exhaustion, fall-ing, and other injuries become so great that chief offic-ers and other leaders will usually not allow their men tobe at the head of the fire. Also under these conditionssmoke and air turbulence often preclude the use of airtankers or helicopters. The only effective perimetercontrol, therefore, is on the flanks of the fire until itreaches some barrier or the weather changes (Los

Angeles County Fire Dep. 1970, Los Angeles City-County Fire Bd. Inquiry 1971, Howard and other 1973).

The strategy of wildland fire control requires perime-ter control, containment of spread, and eventual extin-guishment. Due to the scarcity of water, the tactics ofwildland fire control usually consist of constructing firelines, either by hand or with machines, burning out pre-pared or preexisting control lines, cooling limited areasby air drops of fire retardants, and similar measures.Such work cannot be carried out safely or effectively onsteep hillsides or in close proximity to a high intensityfire in heavy fuels. It must usually be done at somenatural or artificial barrier, e.g., a ridgetop or interstatefreeway. If the wind is very strong, even these barriersoften will not hold because of spot fires caused by flyingfirebrands (Alger 197 1, Los Angeles County Fire Dep.1970, Los Angeles City-County Bd. Inquiry 1971,Howard and others 1973). Consequently wildland firecontrol is basically incompatible with the aim of protect-ing structures.

Most wildland fire protection agencies consider theirprimary statutory mission to be resource protection,and have budgeted accordingly. In spite of this limita-tion, wildland firefighters normally react to humanmoral values when faced with a choice of either savinglife or improved property, or saving several hundredacres of brush or timber. Therefore, even though theirequipment and training are often poorly designed forstructural firefighting and adequate water is usuallylacking, firefighters tend to let the fire spread while theydo the best they can to save lives and structures (Alger1971, Los Angeles County Fire Dep. 1970, Oreg. St.Dep. For. 1978b).

Mountainous terrain complicates fire suppression inseveral ways. The combined effects often make it im-possible to save houses from burning during major wild-land conflagrations, and, as discussed earlier, steepslopes, canyons and ridges complicate and intensify theeffects of wind. Even in the absence of wind, fires racemuch faster up a steep slope than they do on the level. Itis difficult, slow and dangerous to fight fire on steep,rocky side hills. The combined effects of terrain andwind often create smoke and air turbulence conditionswhich preclude the use of aircraft. Mountain roadsmake access and response time slow and difficult forfirefighters and for heavy fire trucks and other equip-ment. Sometimes access becomes impossible whenroads are blocked by debris, other vehicles, or the fireitself or if construction of the roads themselves hasmade them too steep or with curves too tight to betraversed by fire engines or bulldozer transports (Alger197 1, Los Angeles County Fire Dep. 1970, Green 1977,Howard and others 1973).

The control of major wildland fires, usually involvingstructures, is further complicated by the communicationand coordination problems inherent when the fire isbeing fought by multiple agencies, which is usual for


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two reasons. First, wildland fires do not respect politi-cal, jurisdictional, administrative, o r ownership bound-aries. A fire of any appreciable size will usually spreadfrom the protection jurisdiction of one agency to thoseof several other agencies. Secondly, no single agency,even the largest, has the resources to handle a majorconflagration alone. Aid from other agencies, oftenfrom considerable distance, must be called in. As a re-sult, differences in training, equipment, and radio chan-nels regularly exist. The effects of these differences areusually minimized before a fire through joint planningand coordination between adjoining agencies. But ifagencies are responding from a distance in emergencysituations, coordination of the efforts can be a seriousproblem (Alger 1971, Los Angeles County Fire Dep.1970, Los Angeles City-County Fire Bd. Inquiry 197 1,Oreg. St. Dep. For. 1978b, Lowden and Degenkolb1972).

The fire protection available to structures inmountainous areas in or near rural or wildland fuels isoften limited in certain other ways not usual for similarstructures located in cities. Federal and State wildlandfire protection agencies are funded only during the wild-land fire season. At other times of the year, manpoweris sharply reduced, outlying stations are closed, and24-hour service is terminated. In some areas, a localagency (county or fire district) can make up this defi-ciency by entering into a contract with the State forfirefighting services. Other areas receive structural pro-tection from low-budget volunteer fire departmentsfunded by counties, fire districts, or informal donationsfrom private citizens. Their equipment may be old,training inadequate, and response time excessive. Evenwhen professionally manned and well equipped, county

or district fire departments generally have longer re-sponse times than do city departments and water is notas easily available. Thus the fire protection for struc-tures in rural and wildland areas is at a somewhat lowerstandard (Alger 1971, Oreg. St. Dep. For. 1978b).

Floods and ErosionBurning is not the only way in which a residence may

be damaged or destroyed by wildland conflagration. Afire, particularly a large one, anywhere upslope from thestructure is likely to produce flood or erosion damage orboth when the next rains come. For houses near thebottoms or mouths of canyons or those perched on ordirectly under very steep slopes or fills, this danger maybe even greater than that of direct fire damage. Ofcourse, the opposite is true of structures located onridges or high on s10pes.~

That hillside soil bared to the elements by fire is sus-ceptible to accelerated erosion is rather self-evident andhas been noted by many researchers and fire officials.What is not so widely known is that many soil types aremade hydrophobic (water-repellent) by fire. The over-land flow of water during rainstorms is increased by 10to 40 times the normal (unburned) amount because ofthis phenomenon. This tremendously accelerated runoffnot only creates high flood waters, but provides theforce needed to move soil, gravel, and boulders

Ta li f. Reg., For. Serv. 1971; County Sup. Assoc. Calif. 1966;Houts 1974; Los Angeles County 1973; Los Angeies County FireDep. 1970; Rice 1974; Stallings 1970; Zivnuska 1974.


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downslope and downstream and to transport channel plicating factors are involved, a combination of reme-deposits accumulated largely by dry erosion between dies is required to achieve any reasonable degree of firefires (Houts 1974, Rice 1974, Zivnuska 1974). safety for structures in or near wildland areas. Some ofthe potential problems should be solved long before any

structures are built. Other corrective measures shouldLack of Single So l~ ti on be adopted during the development and constructionphases. Still others must be practiced continuously orNo single solution to the fire protection problem can intermittently so long as the structure remains in exist-

be proposed. Because so many hazards, risks and com- ence.

Figure4-The severity of fire hazard in an area can be classified andmapped.


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LAND-USE PLANNING AND ZONING

Land-use planning and zoning are governmental func-tions critical to public safety-including fire protection.But because these functions are political as well, theyare subject to intense differences of opinion and to pub-lic controversy. Therefore, they tend to lag behind de-velopment until the problem becomes aggravated, muchin the fashion of the traffic light that is installed onlyafter eight or ten deaths have occurred at the intersec-tion. Being political they are also subject, even afterenactment into law, to pressures for variances andmodifications. Therefore, they are seldom as effectiveas fire protection personnel would like to see them.With few exceptions, they cannot be made retroactiveand, consequently, older developments are not muchaffected by them. Where land-use planning and zoninghave been enforced, however, they have achievedsignificant degrees of fire safety (Oreg. St. Dep. For.1978b, San Bernardino County Bd. Sup. 1974).

Fire Hazard Severity ClassificationFire hazards are relative and range from the base

level hazard found in any urban area to the extremehazard found amid heavy chaparral on a steep side hillin an area where extreme fire weather commonly occurs(fig. 4), such as southern California. Some countieswhere the problem was recognized early (as long as 40years ago) have taken the simplistic in-or-out approachto wildland fire hazard zoning. Those which have en-tered the field recently (in the past 5 years) have tendedto employ two or three hazard levels in their zoning(Orange County Bd. Sup. 1976, Los Angeles County1937, San Bernardino County Bd. Sup. 1974, Helm andothers 1973).

Probably the best approach to fire hazard classifica-tion or zoning from the standpoints of both technicallycorrect theory and practical application by local plan-ning department staffs is that developed in 1973 by theCalifornia Department of Forestry. It rates fire hazardbased on three weighted values each of fuels, weather,and topography (table 2). In light of more recent infor-mation (Deeming and others 1977) the limits and factorweights may be revised, and whether a "low" or "baselevel" fire hazard classification should be recognized atthe lowest levels of all factors in the table should beexplored. Still the factors used and the approach to

combining and analyzing them are sound. ~echnicali'ytmight be more correct to use up to 20 fuel types and fiveslope classes as recognized by the National Fire DangerRating System (Deeming and others 1977) but thiswould unnecessarily complicate analysis and mapping.

In any event, this system or a modification of it can-identify those areas which present varying degrees offire hazard, including those so hazardous that no con-struction or development should be allowed. It can alsoindicate which areas can be made reasonably safethrough the application of various levels of design, con-struction, and maintenance standards (Orange CountyBd. Sup. 1976, Task Force on California's WildlandFire Probl. 1972, San Bernardino County Bd. Sup.1974, Helm and others 1973).

Any such system should provide for raising to thenext higher level of hazard those limited areas that arein saddles above canyons on the windward side ofridges or at the mouths of canyons on the lee side ofmain ridges (Los Angeles County Fire Dep. 1970).

Proposed Standards: Establish fire hazard severityzones on the basis of a graded classification systemusing fuel loading, fire weather, and slope as primaryfactors. Recognize and map at least two, but preferablythree, levels of hazard. Provide for classification in thenext higher category of especially hazardous situations,such as saddles on ridges above windward canyons andmouths of lee canyons.

Table 2-Fir.(. Ilrr:crrt/ r.rrrc~c/ tl tl7r.rc) 11 '~ ig ht ed'erlrres qf' ~ ~ ' e ( r t l ~ c , r .,firel.s. (1/7(/ opoarrrpl~.v t1 Cnlj for t~i rr~ ~ ~ i l e / l o t ~ c / s ~ ----

Source: Helm and others (1973).l M = moderate hazard, H = high hazard, E = extreme hazard.

111Critical fireweatherfrequencyFuel loading:

Light(grass)Medium(scrub)Heavy(woods-brushwood)

I

Slope (pct .) Slope (pct.) Slope (pct.)0-40 41-60 61+ 0-40 41-60 61+ 0-40 41-60 61 +

M M M M M M M M HM M H H H H E E E

YH H H H E E E E E

I1


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General and Specific PlansIn dealing with wildfire, county or city plans vary

greatly between one local government and another.Some plans merely recognize the fact that a fire problemmay exist; other plans provide a detailed exposition ofthe nature and extent of the problem and a timetable forcoping with it. General plans are prepared by the plan-ning staff and approved by the planning commission andthe governing body of a political subdivision of theState, i.e., county or city. They generally include LandUse, Transportation, Public Safety (which includesfire), and other elements designed to promote orderlygrowth and development. In California, some elementsare mandatory and others optional by State law. Onemandatory element is Public Safety, but in the past,there have been no standards to which this element hadto be prepared3 (Orange County Bd. Sup. 1976, Oreg.St. Dep. For . 1978b, County Sup. Assoc. Calif. 1966,Task Force on California's Wildland Fire Probl. 1972,San Bernadino County Bd. Sup. 1974).Proposed Standards: Require that fire protectionelements of general and specific plans cover both basicstructural protection and protection from wildland fire,that protective measures enumerated in these plans cor-respond to the level of fire hazard severity found to existin the area covered by each plan, and that the fire de-partment participate in reviewing plans.

Zoning OrdinancesGeneral plans and the various uniform codes (build-

ing, fire, etc.) have no force or effect until adopted byordinances of local governing bodies (e.g., countyboards of supervisors, city councils, fire district boardsof directors) and provided with penalty sections (TaskForce on California's Wildland Fire Probl. 1972).

In California, general plans including safety elementsare mandated to counties and cities by State law(California Government Code Sect. 65300 et seq.). Thestandards set by the State to which these plans andelements must be prepared, especially those having todo with wildland fire, have been very weak. Con-sequently, an almost total lack of uniformity exists fromone local jurisdiction to another. The governmentalunits that are larger, most heavily damaged in the past,and more progressive have adopted enabling ordinancescontaining rather comprehensive requirements relatingto fire safety. In contrast, some of the smaller units andthose that have not perceived or understood the sever-ity of the problem have treated it in one sentence or oneparagraph (Task Force on California's Wildland FireProbl. 1972).

One important element of the General Plan is theLand-Use Element. I t establishes the areas that can bedevoted to different uses (e.g., residential, commercial,

manufacturing, agriculture, open space). This elementhas great potential for enhancing structural fire safety inwildland areas if wildland fire hazard severity classesare accounted for during its development. So far thispotential has rarely been considered, and no case hasbeen found where the Land-Use Element of the Gen-eral Plan was actually implemented in this manner.3

The Uniform Building Code (UBC) published by theInternational Conference of Building Officials has beenadopted by many counties and cities. Others have nosuch code or ordinance. A major component of theUBC is the establishment of Fire Zones I, 11, 111.These zones set standards by requiring decreasing de-grees of fire safety to be built into structures of varioustypes of occupancy and prohibit certain occupancies inZones I and 11. Zone I11 generally encompasses resi-dential areas having the lowest (base level) fire dangerand requires minimal fire safety construction. In allzones, the standards are designed to provide protectionfrom fires starting within the building or in another onenearby (3 to 20 feet). The problem of fires approachingthrough large expanses of vegetation is not addressedanywhere in the UBC (Task Force on California'sWildland Fire Probl. 1972, Int. Conf. Build. Off. 1976).

A few jurisdictions that have adopted the UBC byreference in an ordinance have amended it in variousways to attempt to cover the wildland fire problem.Some have added fire zones and incorporated certainrestrictions and requirements for structures located inthem. Others have declared fire hazardous wildlandareas to be in Fire Zone 11. In most cases the onlyeffective remedial measure is the requirement of fire-resistive roofing (Build. News, Inc. 1977, County Sup.Assoc. Calif. 1966, San Bernardino County Bd. Sup.1974).

Proposed Standards: Recognize varying degrees ofwildland fire hazard in local ordinances. Establish con-struction and spacing standards commensurate witheach degree, and make such standards applicable to res-idences and their appurtenant structures as well as toother types of occupancy.

Spaclusg and Buildr'ng DensityTo provide a reasonable degree of fire safety, building

spacing and density must be different in mountainousareas, wildlands, and rural areas than they are in urbanareas. This differentiation is needed because the usualsource of ignition of the structure in the wildland orrural setting is external while in the more developed citysituation it is internal. Exceptions to this general rule do

3Hastings, John H . 1977. Fire safety guides for wildland planners.(Unpublished report on file, Region V , California Department ofForestry, Monterey, Calif.)


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occur, but they are relatively rare (Alger 1971, LosAngeles City-County Fire Bd. Inquiry 1971).

The Uniform Building Code (UBC), Uniform FireCode (UFC), and most subdivision codes are based ontwo assumptions: an internal ignition and a fire depart-ment response time of less than 15 minutes. These arerelatively safe assumptions in most cities and some firedistricts, but are valid only in very limited areas wherefire protection is provided by a county, State, or Fed-eral agency. They are almost totally irrelevant in mostmountain and wildland areas where only seasonal re-source fire protection is usually available (Alger 1971).

In addition to being subject to external ignition and upto 2-hour response times, structures built on slopingground are affected by the same fire behavior phenome-non discussed earlier in relation to the wildland fuel.The slope creates an effect similar to that of wind andcauses fire to spread faster uphill than downhill or onthe level. Buildings situated on slopes should be re-quired, therefore, to be spaced farther apart than similarbuildings built on essentially level ground. On exces-sively steep slopes (more than 55 percent), all woodframe construction probably should be prohibited3 (LosAngeles County Fire Dep. 1970, Oreg. St. Dep. For.1978b, County Sup. Assoc. Calif. 1966, San BernadinoCounty Bd. Sup. 1974, Helm and others 1973).

In recent years a new concept in residential develop-ment has been adopted in some areas. This is the clusterdevelopment in which the population density limitationsof general land-use plans are met by placing individualhomes or multifamily residences (e.g., duplexes, apart-ments, condominiums) in small groups on smaller lotsthan would otherwise be required. The land area thussaved is reserved for community open space. This prac-tice is esthetically pleasing to most people, and can alsoimprove the fire safety in rural or wildland areas as longas certain minimum spacing standards are followed.The space between'bui~din~s,or instance, should notbe less than half that required between residences in

conventional subdivisions in similar areas. And the na-tive vegetation should be modified at least to fuelbreakstandards of width and hazard reduction in the spacesbetween clusters (Task Force on California's WildlandFire Probl. 1972, Colo. St. For. Serv. 1977).

Because of the close spacing commonly employed inmobile home parks, those situated in wildland firehazardous areas are particularly susceptible to destruc-tion or serious damage from conflagrations. Requiredspacing between mobile homes in such parks should beno less than that allowed between buildings in a clusterdevelopment in a similar fire hazard classification zone(Los Angeles County Fire Dep. 1970).

Most of the references on structure density and spac-ing base their recommendations primarily on slope.Only rarely are the other primary factors contributing towildland conflagrations (i.e., fuels and weather) men-tioned, mostly in work done in the late 1970's. The mostlogical and defensible standard on which to base struc-ture density and spacing requirements is fire hazardseverity classification and mapping (Colo. St. For.Serv. 1977, Helm and others 1973).Proposed Standards: Establish minimum standardsof building spacing and density, as shown below. Pro-vide for the imposition of higher standards or the pro-hibition of building where local conditions (e.g., exces-sively steep slopes, ridge saddles, canyon mouths)create critical fire hazards:

Individual buildings ClustersProp.

Hazard Density Spacing line Between Betweenclass: setback bldgs. clusters

FeetModerate 3 per 60 30 30 100

acreHigh I per 80 40 40 150

acreExtreme l per 100 50 50 2004-5acres


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PROPERTY DEVELOPMENTOnly the developer of a property can provide some of

the vital means of fire protection, such as access andwater supply. It is the developer's responsibility toknow about them, and to design them into the projectbefore any structures are erected. But others have re-lated responsibilities. Planning departments should de-velop and legislative bodies should adopt minimumstandards. Planning departments, with advice andassistance from operating departments (e.g., fire, publicworks, sanitation), should enforce the standards even ifthey must deny approval of nonconforming proposals.People with financial interests (e.g., bankers, insurers)should satisfy themselves that firesafe features are in-corporated in the project before committing their re-sources. All development plans should employ the mas-ter planning concept in order to properly assess the in-teractions between various elements (e.g., publicsafety, transportation, sanitation, water, school^).^^^

One of the most important aspects of land develop-ment from the fire protection viewpoint is access. Itinvolves a great deal of engineering and expense and isalmost impossible to improve or alter after developmentis complete. If inadequate, access becomes critical dur-

4Colo . St. Fo r. Se rv. 1977; County Sup. Assoc. Calif. 1966; LosAngeles County Fire D ep. 1970; Orange County B d. Sup. 1976;Oreg . St. Dep . Fo r. 1978a, 1978b; San Bernardino B d. Sup. 1974.

ing a conflagration both from a firefighting standpointand with regard to life safety3 (Alger 197 1, Los AngelesCounty Fire Dep. 1970,+LosAngeles City-County FireBd. Inquiry 1971, Oreg. St. Dep. For. 1978a, CountySup. Assoc. Calif. 1966, Colo. St . For . Serv. 1977).

Adequate ingress and egress are necessary to allowsafe and rapid passage of both fire equipment and pri-vate vehicles in opposite directions simultaneously. Butthey can be costly not only in the expense of road con-struction but also in the resulting reduction of saleablelots because they require space. This is particularly truein lot-splitting situations where the original parcel canbe divided only into four or less new parcels, therebyreducing the opportunity to spread costs. Adequate ac-cess is a cost that must be borne, however, if past disas-ters are not to be repeated time and again (Alger 197 1,Los Angeles County Fire Dep. 1970, Orange CountyBd. Sup. 1976, Oreg. St . Dep. For. 1978b, County Sup.Assoc. Calif. 1966, San Bernardino County Bd. Sup.1974).Proposed Standards: Meet all of the following stand-ards; deny any variances that do not show positivelythat they will not adversely affect firefighting andevacuation capabilities:

1. Provide two or more routes of access to a publicroad, preferably on opposite sides of the develop-ment (loop roads with single entry do not meet thisstandard).2. Dedicate streets and roads to public use and main-tenance. If they are allowed to remain private, pro-vide for their maintenance in perpetuity.


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3. Set minimum dedicated right-of-way at 60 feet toprovide two 12-foot hard surface traffic lanes, two8-foot parking lanes, and two 10-foot roadside stripswherein fire hazards shall be abated.

4. Base minimum centerline radius of curvature ofstreets and roads on fire hazard severity classifica-tion: moderate-50 feet, high-75 fee t, extreme-100 feet. Allow no variance to less than 50-footradius.

5. Establish road grade based on fire hazard severityclassification: moderate- 12 percent, high-10percent, extreme-8 percent. Allow no variance toexceed 200 feet in length or 2 percent above stand-ard, and only on straight line portions of the road.

6. Do not permit any dead-end stree ts. Allow cul-de-sacs provided they do not exceed these lengthsbased on fire hazard severity classification:moderate-800 fee t, high-700 feet, extreme-600feet. Require cul-de-sacs to have a turning area atthe end of not less than 90-foot diameter.

7. Require bridges to have a minimum load limit of36,000 Ibs. (18 tons), and to not be narrower thanthe driving portion of the road serving each end.

8. Stipulate that each lot or parcel must have directaccess to a road meeting the above standards, suchaccess to be traversable by a modern structural fireengine.

9. Design road and street intersections to be as closeto 90 degrees as terrain will permit, for at least 80feet from intersection centerlines, and in no caseallow the angle of such road intersections be lessthan 45 degrees.

10. Clear the area within 200 feet on each side of thecenterline of all roads and maintain it to fuelbreakstandards-except for structures.

Water SupplyWater is still the most effective tool for fighting wild-

land fire when and where it can be obtained in sufficientquantity. It is really the only effective tool for fightinghome and most other structural fires. Therefore, a large,dependable source of water above that required fornormal daily domestic purposes must be provided for atthe time a subdivision (including mobile home park),shopping center, recreation area, or individual homesiteis planned and developed3 (Alger 197 1, County Sup.Assoc. Calif. 1966, Natl. Fire Prot. Assoc. 1974).

The amount of water reserved for firefighting pur-poses and the size and type of delivery system provideddepend on (a) the degree of wildfire hazard involved(fire hazard severity classification); and (b) the type andlocation of the occupancy (home or mobile home in asubdivision; farm or other individually developedhomesite; multiple such as commercial, recreational,industrial, apartments, etc.). The water requirements

for multiple occupancies are usually stipulated by theinsurance carrier or local fire department or both. Al-though normally based on requirements for fighting aninterior fire, they are usually adequate for protecting thebuilding from an encroaching wildland fire as well, be-cause usually these requirements are set quite high toreflect both the financial property risk and the multiplelife risk.

Adequate water for firefighting purposes, either by afire department or by the occupant, has been unavail-able and unreliable on many occasions where homeswere involved. In some cases, adequate water wasavailable but not developed, as the potential fire prob-lem was not recognized. In other situations the problemwas recognized but considered a remote possibility.Sometimes the cost was considered too high. Some-times a sufficient water supply was not available at anyprice-and in such a situation, the structure should nothave been built. A common cause of water deficiency isthe practice of extending or adding on to a subdivisionwhere the water system was adequate for the originaldevelopment and is adequate for domestic service to theaddition but is insufficient to provide fire flows both tothe original and to the additional development^.^ (Alger1971, Los Angeles County Fire Dep. 1970, OrangeCounty Bd. Sup. 1976, County Sup. Assoc. Calif.1966).

In contrast to normal daily use, consumption of waterfor firefighting purposes is of relatively short durationbut of high volume. Water is also used duringemergency conditions when electric power service maywell be interrupted. Different engineering, therefore, isrequired than would be needed for a purely domesticwater system. Water supplies for firefighting involvelarge storage facilities, high-volume mains, and depend-able delivery (either gravity or pumps with alternatestandby power sources). These facilities should be pro-vided during the development phase as their priceskyrockets if they must be added after development andoccupancy3 (Orange County Bd. Sup. 1976, Oreg. St.Dep. For . 1978b, County Sup. Assoc. Calif. 1966, Natl.Fire Prot. Assoc. 1974).

P ropose d S tandards : Adhere to t he following stan-dards as they apply to individual projects, and do notpermit variances because they would expose both lifeand property to unacceptable risks:

I. All structural developments regardless of type or lo-cation to have a dependable 'supply of wateradequate for both normal daily consumption andemergency fire needs. P

2. Where homes or other small buildings are suppliedby their own independent water systems, they are tohave a minimum storage capacity of 2500 gallons,supply mains of at least ]%-inch diameter, one 1%-inch standpipe conveniently located for fire enginefilling, and at least two hose outlets 50 or more feet


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from the building in addition to outlets on the ex-terior of the building.

3 . The water systems of commercial, industrial, recre-ational, and multiple-dwelling (apartment or con-dominium) developments are to be engineered tomeet Standard 1 above and approved by the fireagency having jurisdiction.4. Subdivisions and mobile home parks are to be pro-vided with 6-inch or larger circulating (loop) mainsand storage capacity sufficient to provide theminimum fire flow indicated below for at least 2hours with a residual pressure of 30 lb/in2, and havefire hydrants of at least 6-inch diameter with thesemaximum spacings:

Hazard class: Hydran t spacing Minimum flowI f f ) (gallmin)Moderate 700 500High 500 750Extreme 300 1000

5. Any area large enough for helicopter landing andtake-off (e.g., school yard, parking lot) is to have atleast one hydrant.

Perimeter Protection and F're AccessThe point or line at which the urbanlwildland inter-

face is most critical is the edge of the undisturbed nativevegetation nearest to the structure. For a farm or otherwildland home, this is the edge of the clearing made forthat building. How thorough and extensive the clearing

must be is the subject of various State and county laws.The same laws apply to clearing around buildings insubdivisions and mobile home parks, but are seldomadequate to meet the life and property threats involvedin these more densely developed areas. What is neededin these developments is some sort of perimeter clear-ance or treatment of the native vegetation to a greaterdistance from the structures than that required by exist-ing statutes and ordinances (Orange County Bd. Sup.1976, Oreg. St. Dept. For. 1978b, County Sup. Assoc.Calif. 1966, Task Force on California's Wildland FireProbl. 1972).

The greatest distance to which vegetative treatment isrequired by any existing law is 100 feet from the struc-ture. Perimeter treatment around subdivisions andother high value areas (e.g., mobile home parks, recrea-tion areas, shopping centers) should be at least to fuel-break standards (200 feet minimum). And it should em-body certain additional features for two reasons: (a)Vegetative and structural fuels must be physically sepa-rated by enough distance to reduce to an acceptablelevel the danger of ignition of structures by direct flameimpingement or radiation-an even greater clearance(usually impractical if not impossible) would be neces-sary to protect against windborne firebrands; (b)firefighters must have a place in which to fight the firebefore it reaches the structures, and so it is necessary toincorporate features which allow access by thefirefighters and their equipment to the treated area (LosAngeles County Fire Dep. 1970, Orange County Bd.Sup. 1976, County Sup. Assoc. Calif. 1966, Green1977).

t u r a a t ive brush,

Local street on ridge

Figure 5 -Fire access easements areneeded for firefighters to get to areastreated for fuel modification (Orange Native brushCounty Bd. Sup. 1976).


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This dual need can be met in several ways and manycombinations thereof. Probably the best means from thefirefighter's standpoint is a perimeter street with struc-tures on the inside and a fuelbreak or greenbelt on theoutside. Usually this design is economically feasibleonly if the adjacent area is to be subsequently sub-divided. In certain topographic situations, such a designis impossible (Orange County Bd. Sup. 1976).

Another way to achieve perimeter protection is toconstruct a fuelbreak or greenbelt behind the outsidestructures ( f ig. 5). Fuelbreaks are strips of land in whichthe volume of vegetative fuel is reduced to an accept-able level and maintained in that condition. Greenbeltsare similar strips of land wherein not only is the volumeof native vegetation greatly reduced but much or all of itis replaced with irrigated introduced species. Stripparks and golf courses, are examples of greenbelts.They perform multiple functions (i.e., fire protection,recreation, esthetic benefits) and can often be made topay for themselves (Los Angeles County 1973,, Green1977).

Although practical in economic and sometimes phys-ical terms, fuelbreaks or greenbelts present some prob-lems. Access to the treated area by firefighters is deniedunless fire access easements are provided and dedicatedto such use. These easements should be wide enoughand of low enough gradient to allow access bymotorized fire equipment as well as by personnel(Orange County Bd. Sup. 1976, County Sup. Assoc.Calif. 1966).

Other developments which can serve the purpose ofperimeter fire protection, at least for limited pieces ofthe perimeter, are recreation areas (particularly water-based ones), parking lots, school yards, and baseball orother athletic fields. With such developments placed onthe perimeter the amount of otherwise unproductivefuelbreak and easements needed would be reduced3(Alger 1971).Proposed Staizdards: Include reduction of nativevegetative fuels to at least fuelbreak standards as part ofperimeter fire protection for subdivisions and mobilehome parks. Provide access lanes to the treated area atleast 12 feet wide for firefighting manpower and groundequipment at intervals not to exceed one-quarter mile.Base the minimum width of the treated strip on firehazard severity classification: moderate-200 feet,high-300 feet, extreme-400 feet. Dedicate suchtreated areas and access lanes to public use and providefor their maintenance in perpetuity.

Electric Power DistributionOverhead transmission and distribution of electric

power is a major source of ignition for the conflagrationsthat have destroyed many hundreds of homes inCalifornia and elsewhere in recent years. Contrary to

popular belief the large high-voltage transmission linesare not the worst offenders. In one study they accoun-ted for less than 8 percent of the fires over 5000 acres insize. They are commonly built of sturdy materials,maintained with adequate vegetative clearances, and in-spected frequently and thoroughly (Task Force onCalifornia's Wildland Fire Probl. 1972, Moore 1977).

Distribution circuits accounted for nearly 17 percentof the conflagrations studied (Task Force on Califor-nia's Wildland Fire Probl. 1972). This proportion wasexceeded only by arson and was equalled by machineuse. All other fire causes were smaller in number. Dis-tribution circuits are of two types: primary and second-ary. Primary circuits bring the power from the substa-tion to the user's transformer. Primary electric powerdistribution circuits are a serious cause of wildland con-flagrations. The thousands of miles of these lines pre-sent a tremendous exposure and an almost insurmount-able problem of inspection and maintenance. Secondarycircuits, which convey power from the transformer tothe point of use (e.g., home, pump), usually cause firesbecause of inadequate vegetative clearance which is notnow regulated by any State or local law. Secondarycircuits cause nearly one fire for every two caused byprimary distribution lines (Calif. Div. For . 1972, Moore1977).

In about the lower half of their voltage range (i.e., 2.4to 17 kilovolts), primary distribution circuits can suc-cessfully be installed underground rather than over-head. In the foreseeable future, even higher voltagelines can be installed underground. The subdivisioncodes of many cities now require such installation in allnew subdivisions, although usually for visual estheticreasons. The same requirement could be imposed inrural and wildland areas for fire protection reasons.Such a requirement would eliminate both primary andsecondary circuits as sources of vegetation fires sincethe transformers would be at ground level or below.From this location the secondary circuit (service drop)is almost always placed underground also (Governor'sStudy Comm. Conflagrations 1966, Task Force onCalifornia's Wildland Fire Probl. 1972, Moore 1977).

If for some reason (e.g., excessive rock, preexistingoverhead service) the cost of underground installationcannot be justified in relation to fire safety benefits, thedeveloper should arrange for and the permitting agen-cies require very high standards of construction, vegeta-tive clearance, inspection and maintenance of overheadpower lines (Governor's Study Comm. 1966, Oreg. St.Dep. For. 1978a, County Sup. Assoc. Calif. 1966, TaskForce on California's Wildland Fire Probl. 1972, M9ore1977).

Proposed Standards:I . Install all new distribution circuits and extensions of

existing circuits underground in fire hazardous wild-land areas, if technologically feasible.


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2. Place underground, all distribution circuits (new orexisting) carrying less than 20,000 volts in areas of"extreme" fire hazard severity class.

3. Maintain the following clearances between vegeta-tion and conductors (wires) for all overhead powerlines:Fire hazard Seconda ry Primaryseverity class: distribution distribution0-750 volts 2.4-17KV 18-35KV

Fee t

Moderate 2 4 6High 4 6 8Extreme 6 8 10

Street Names and NumbersSubdivisions are usually provided with visible street

names or numbers and lot or building numbers as aconvenience to the buyers and visitors. Often, how-ever, the signs are hard to read, sometimes even diffi-cult to find. Many rural and mountain areas have be-come essentially urbanized through lot splitting andother sale of individual parcels and subsequent con-struction, and in these situations there is no developerto assign names and numbers. Roads often get theirnames from their destinations, names of old-time prop-erty owners, etc. Parcels or homes commonly are as-signed box numbers by the Postal Service.

Positive identification of location is not merely con-venient to a firefighter or other public safety officer re-sponding to a reported emergency or radioing for help;it is an absolute necessity. Developers or others assign-ing and posting names and numbers can greatly assist in

providing adequate fire protection if they will make thesigns as permanent as possible and large enough andwith enough color contrast and reflective character tobe read easily from a moving vehicle at night as well asin the daytime3 (Oreg. St. Dep. For. 1978a, Oreg. St.Dep. For . 1978b, Task Force on California's WildlandFire Probl. 1972, Colo. St . For. Serv. 1977).Proposed Standards: Construct signs of nonflamma-ble materials, with letters at least 3 inches high, half-inch line width, and a reflective color that contrastssharply with the background of both the sign itself andthe surrounding vegetation.

Fire Station SitesExisting fire stations in wildland areas usually are not

located correctly nor are they manned and equippedadequately to provide structural fire protection to sub-divisions and other developments. Developers of largesubdivisions or mobile home parks or of shopping cen-ters or apartment or condominium complexes shouldrecognize this deficiency and dedicate one or more sitesfor structural fire stations at the outset. After develop-ment is complete, suitable sites will no longer be avail-able (Oreg. St. Dep. For. 1978b, County Sup. Assoc.Calif. 1966, San Bernardino County Bd. Sup. 1974,Colo. St. For. Serv. 1977).Proposed S t andards : Dedicate fire station siteswhen:1. No fire station capable of providing structural fire

protection exists within 4 miles of the development.2. The development is to encompass more than 640

acres or is to have an occupant density of more thaneight dwelling units per acre.


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STRUCTURALDESIGN ANDCONSTRUCTION

Because of the behavior of wildland fires, how abuilding is designed and constructed is the most impor-tant factor in providing fire safety for a home or otherstructure. Properly built homes can survive conflagra-ticns even if many of the other protective measures dis-cussed in this report are absent. Even homes apparentlywell separated from wildland vegetation will be de-stroyed if poorly designed and if constructed withoutregard to fire safety. The architect and building contrac-tor, therefore, are key figures in providing safety. Manyothers (e.g., legislative and governing bodies, buildinginspectors, financers, insurers, buyers) need to beknowledgeable and be able to exert pressure that willguarantee adherence to fire safe practices in design andcons t r~c t ion .~ ,~

RoofingThe roof is the most vulnerable part of a building

during a fire-especially one in chaparral or oak areas.Because of its horizontal component, a roof can catchand hold the flying firebrands almost invariably associ-ated with the strong winds and convection columnscharacterizing these fires. Unlike ground fire, thesefirebrands soar beyond any type of firebreak, natural or

Wg er 1971;Task Force on California's Wildland Fire Probl. 1972;County Sup. Assoc. Calif. 1966; Howard and others 1973; Lowdenand Degenkolb 1972; Oreg. S t. Dep. For . 1978a; Smaus 1978a, 1978b;Wilson 1962.

artificial, and thus endanger structures as far as a milcaway from the wildfire (Alger 1971, Los AngelesCounty Fire Dep. 1970, Howard and others 1973, Low-den and Degenkolb 1972, Smaus 1978b, Wilson 1962).

Recognizing this vulnerability to fire from externalsources, the Uniform Building Code requires "fire-retardant roof coverings" in Fire Zones I and 11, thehigh value and high life hazard areas in or near the busi-ness sections of cities. Many local jurisdictions haveadopted the UBC by reference or by basing their owncode on it. A few local jurisdictions have amended theUBC or their own codes to require "Class C" or betterroofing as defined in UBC Standard 32-7 in wildfirehazardous areas. Most wildland areas still have no re-quirements regarding roofing materials (Build. News,Inc. 1977, San Bernardino County Bd. Sup. 1977, LosAngeles County 1937, Intl. Conf. Build. Off. 1976,Holmes 1971).

Most structures at or near the urbanlwildland inter-face are either not covered by a building code, are inFire Zone 111, or are permitted to have any type ofroofing material, or at most, Class C roofing. In the past30 or 40 years, wood shingles or shakes have becomepopular with architects and buyer's alike. Various fire-retardant treatments have been available for about 20years, but only in the past 10 years or so have zpy ofthem been made relatively permanent (i.e., will retain asignificant degree of fire-retardancy for 5 years ormore). Although shakes and shingles with Class C rat-ing are available, none meet the Class B requirement for"fire-retardant" roofs as defined in UBC Standard 32-7.


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Treated shakes or shingles cost more than untreated,and in the absence of a local code requiring them areseldom installed. Thousands of homes and other build-ings exposed to the threat of wildland fires, therefore,are roofed either with untreated shakes or shingles, withones which were merely dipped in fire-retardant chemi-cal, or with ones from which the treatment has beenleached by the weather. These roofs are not only seri-ous hazards to the buildings on which they are installedbut also to any other buildings downwind from themwhich are similarly roofed. Once a shake or shingle roofcatches on fire, shakes or shingles peel off and are car-ried as new firebrands on the convection column and thewind.6

Many types of firesafe roofing materials are available.Some are less expensive than wood shakes or shingles,others more costly. They include Class A and B built-up assemblies, Class A and B prepared roofing, prop-erly installed Class C mineral surfaced asphalt shingles,asbestos cement shingles or sheets, concrete slabs,metal, slate shingles, fiber glass shingles, and clay orconcrete tile. Although most of these materials are notcurrently popular for residences, many can be madequite attractive-especially if the rest of the building isdesigned to accommodate them (Oreg. St. Dep. For.1978a, Intl. Conf. Build. Off. 1976, Smaus 1978a).

The probability that a house of a given roof type andwith brush clearance will be burned can be estimatedfrom records compiled by the Los Angeles City FireDepartment for the 1961 Be1 Air Fire, in southernCalifornia. These records cover a sampling of 1,850homes. For the probabilities shown it is assumed thathouses are exposed to the rate of wildfire destructionobserved in the Be1 Air Fire. Values have been interpo-lated to match the brush clearance categories of theinsurance industry (Howard and others 1973):

Roof typeBrush clearance Approved by Unappro ved by(ft): insurance industry insur ance industry

The most cost-effective means of protecting homesfrom destruction by fire in or near the wildlands is acombination of approved fire-resistive roofing andclearance of 100 feet or more from the native brush foreach home ( f ig . 6).Proposed S tand ards: Base roofing materials requiredon the following fire hazard severity classification:moderate-Class C, high-class B, extreme-Class4.

Another Achilles' heel to the attack of homes bywindborne firebrands is an unprotected attic or under-floor vent. Although unprotected vents are not as well-documented as a cause of structure fires as flammableroofs, flying embers can easily enter a structure throughsuch vents. If they land on any ignitable material, theinaccessability of the interior to suppression efforts al-most certainly will lead to destruction of the house. Thepresence of flammable materials (e.g., dry leaves orgrass, waste paper) is almost assured by the samemechanism-strong wind-that brings the firebrand.To remove this hazard, vents can be screened to pre-vent the entrance of flammable materials and firebrandsbut still allow the passage of air.3,Proposed Standards: Use vent screens of corrosion-resistant wire mesh with a mesh size of one-quarterinch.

Overharags and Sar'lt ConstructionTwo other common architectural practices presentserious fire hazards to a home built in or near the wild-

7B uilding ~ e w s ,nc. 1977; Tas k Fo rce on California's W ildlandFir e Probl. 1972; Gov erno r's S tudy Comm . Conflagration 1966;Howa rd and others 1973; Lo s Angeles Fire Dep . 1970; Natl . F ireProt. Assoc. 1974; San Bernardino County Bd. Sup. 1977; Wilson1962.

Shingle or shake roof----- Fire retardant roof

Distance from brush to home in feet-6Alger 1971, Holmes 1971, Howard and others 1973, Los Ange]es Figure 6-T he greater the distance between aCity-County Fir e Bd. Inquiry 1971, Lo s Angeles County Fire D ep. dwelling and brush , the better the chanc e it has

1970, Low den and Degenk olb 1972, Wilson 1962. of escapin g destruction in a fire (Wilson 1962).


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lands: (a) overhanging or projecting members (e.g.,eaves, balconies, raised sun decks), which are likely tobe found anywhere and are always dangerous; and (b)stilt construction. The latter, although dangerous any-where, is particularly so on sidehill sites because theuphill side forms a trap for heat and flames. The danger,directly caused by vegetative fuels being under thebuilding, is then aggravated by the wind accompanyingconflagrations (County Sup. Assoc. Calif. 1966, Colo.St. For. Serv. 1977, Wilson, 1962).

Structures with overhangs or stilt construction, orboth, are usually ignited by flames sweeping against theunderside of the projection or the building itself. Awildfire running uphill ahead of a strong wind throughheavy brush or timber to within a few feet of a housebuilt on stilts and with a cantilever balcony and 4- or5-foot eaves is a positive prescription for disaster. Thissequence is not as uncommon as it might sound. Hill-side homes often offer spectacular views, and balconiesare often provided to take full advantage of the view.Wide eaves are commonly built to shade windows. On ahillside, one side of a house may be at ground level orbelow while the other side is 15 or 20 feet, or possiblymore, above ground level (Deeming and others 1977,Helm and others 1973, Smaus 1978b, Wilson 1962).

These architectural fire hazards can be overcome by anumber of measures. One is to construct any overhang-ing member or building of nonflammable materials (e.g.,metal or concrete) of at least 1-hour or 2-hour fire resis-tive materials as defined in the UBC. Another is toencase stilts so that there is no opening below the floorof the building, balcony or sun deck. Roofs can be builtwithout eaves. Sidehill houses can be designed with twoor three floor levels, thus utilizing what otherwise wouldbe not only a fire trap but wasted ~ p a c e . ~ , ~

Proposed Stand ards:1. Construct eaves, cantilever balconies, and othersimilar overhangs with undersides of materials thatmeet the following UBC specifications, dependingon fire hazard severity class: moderate-fire-retardant pressure treated wood or equivalent;high- 1 hour; extreme-2 hour.

2. For structures supported wholely or in part on stilts,encase all underfloor areas to the groundline withmaterials meeting the standards for exterior verticalwalls in the same area or zone.

GlassWindows can easily be a weak point in the fire protec-

tion of a home for two reasons. They allow entrance of

8Building News, Inc. 1977; Task Force on California's WildlandFire Probl. 1972; Colo. St. Forest Serv. 1977; County Sup. Assoc.Calif. 1966; Int. Conf. Build. Off. 1976; Lowden and Degenkolb 1972;Smaus 1978a, 1978b.

radiated heat of such intensity that interior materials(e.g., furniture, drapery, clothing, papers) are ignited.And they admit convective heat, firebrands, or flameswhen they are open or broken. Large picture windowsand sliding glass doors are particularly vulnerable tothese hazards. The orientation of the glass surface willdetermine the degree of hazard it represents. If it is onthe windward side of the building or is facing toward aconcentration of vegetative fuel, the danger isheightened. If it is downwind or shielded by some non-flammable obstruction, the danger will be reduced(Alger 1971; Los Angeles County Fire Dep. 1970;Lowden and Degenkolb 1972; Smaus 1978a, 1978b;Wilson 1962).

Windows cannot be abandoned or prohibited. Theopportunity to enjoy a spectacular view or the feeling ofspaciousness afforded by a sliding glass door openingonto a patio, sun deck, or swimming pool is hard to giveup. But the danger of fire can be reduced by installingnonflammable shutters or fire-retardant drapes; byorientating away from concentrations of vegetativefuels; by shielding with nonflammable balconies ordecks; and by using tempered o r double-paned windowsor both, or wire glass (Orange County Bd. Sup. 1976;Oreg. St. Dep. For. 1978a; Task Force on California'sFire Probl. 1972; Lowden and Degenkolb 1972; Smaus1978a, 1978b).Proposed Standards:1. Hold to a minimum the size and number of glazed

openings on the side of the house facing the normalfire carrying wind or the downhill side or both.

2. Use extra-strength glass (thick, safety, tempered, ordouble-paned, or both).

3. Protect windows and sliding glass doors with non-flammable shutters, balconies or decks, and fire-resistant drapes.4. Orient any glazed openings so that they do not faceconcentrations of vegetative fuels within 100 feet,unless such openings are provided with fireproofshutters.

Most home fires in urban areas have internal sourcesof ignition. Therefore, the materials of which their ex-terior walls are constructed are of relatively minor im-portance from a fire protection standpoint. The ar-chitect, therefore, has considerable latitude in design.By contrast, home fire ignitions duiing a wildfire arealmost entirely external (assuming all openings are pro-tected as discussed earlier). Thus fire-resistancy of,,ex-terior walls becomes of great importance, and thechoice of materials must be restricted. Contrary to thissafety requirement is the strong tendency on the part ofboth architects and buyers toward an increasingly rusticappearance as the site gets deeper into the chaparral or


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woods. As a result many structural fires in rural areashave started by direct ignition of external wood siding,garage doors, and porches. This hazard is heightened ifconcentrations of fuels (e.g., vegetation, firewood,wood fences) are too close to the wood-encased house(Alger 1971, Los Angeles County Fire Dep. 1970).

Many materials are available for exterior wall use thathave varying degrees of fire-retardance up to 2-hour rat-ings or even higher. Some of these can be made to ap-pear quite rustic. Others have unique visual qualities oftheir own. They vary in ascending order of fire safetyfrom wood siding or panels pressure-treated with fire-retardant chemicals (same leaching problems as forshingles and shakes) through stucco, metal siding,brick, asbestos-cement shingles or corrugated panels toconcrete block or poured concrete and rock walls. Toachieve full fire-resistant effect, all but the solid con-crete or rock walls must be properly applied over suit-able base materials, as defined in the UBC, continu-ously from the ground or foundation to the roof oreaves3 (Orange County Bd. Sup. 1976, Oreg. St. Dep.For . 1978a, County Sup. Assoc. Calif. 1966, Intl. Conf.Build. Off. 1976, Smaus 1978a).

Proposed Standards:1 . Build exterior walls of such materials as to provide

the following degrees of

protecting residences from wildfires: a guide for homeowners, lawmakers, and planners

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