models for mitigating wildfire hazards through zoning · the essentialissue in wildfire hazard...

ISSUE NUMBER THREE

PRACTICE WILDFIRE MITIGATION

AMERICAN PLANNING ASSOCIATION

ZONINGPRACTICE March 2005

Models for Mitigating Wildfire HazardsThrough ZoningBy Jim Schwab, AICP, and Stuart Meck, FAICP

Wildfires have a nasty habit of grabbing the entire nation’s attention with televised

images: forests aflame, conflagrations licking at and then overwhelming communities at

the urban edge, people returning to a home that has been reduced to rubble.

The essential issue in wildfire hazardmitigation is denying fuel to the fire. With thatfocus in mind, one can understand someunique features of zoning in wildfire hazardareas, including the use of vegetation man-agement plans, fire control plans, public dis-closure and information requirements, andstandards for access, fuel reduction, watersupply, and construction. All involve variousmeans of trying to reduce the supply of com-bustible materials within probable reach offlames from a forest fire surrounding a subdi-vision, planned unit development, or otherresidential area. It is particularly importantthat planners understand that, unless meas-ures are taken both in building codes and inlandscaping, houses can magnify the intensityof a wildfire by increasing the ready supply ofcombustible materials in its path. When thathappens, the homes themselves may be per-petuating a wildfire in ways that the surround-ing forest cannot.

MODEL CODESTwo model codes exist that may serve toguide planners in drafting their own localrequirements. NFPA’s “Protection of Life andProperty from Wildfire” (NFPA 1144) estab-lishes standards used to provide minimumplanning, construction, maintenance, educa-tion, and management elements for the pro-tection of life, property, and other values thatcould be threatened by wildland fire. TheInternational Code Council’s InternationalUrban-Wildland Interface Code contains simi-lar provisions.

NFPA 1144 contains measurable stan-dards for access, ingress, egress, evacuation,building design, location, and construction,

Most important are the community’s criteriafor designating the wildland/urban interface,a concept that is easily misunderstood. TheWUI, notes Michele Steinberg, the FirewiseCommunities Support Manager for theNational Fire Protection Association (NFPA), isnot a fixed location but is defined by a set ofconditions that can change over time. Purelyundeveloped forest is not part of the WUI pre-cisely because it lacks an interface with urbandevelopment, but a forested area can becomepart of the WUI if such development is intro-duced into the area. The implications for zon-ing are significant. A city can apply zoningrestrictions to the WUI, but the WUI itself mostclosely resembles a floating zone, not a fixedgeographic area. On the other hand, undevel-oped areas can undergo severe wildfires, andplanners can map areas according to theirpropensity for wildfires and zone them accord-ingly as more or less suitable for developmentin view of the dangers.

If zoning even enters the discussion as peoplereact, it is often as they ask, “Why are thosepeople living out there anyway?”

In fact, howe ve r, growi ng numbers o fco m m un i t i esa re pla n n i ng for wild f i re ha za rdsand ta ki ng sp e ci f i c ste ps to re vise their la n d -use reg ula t i o ns to add ress the problem. In an e w l y re leased PA S Re p o rt, Planning forW i l d f i r e s ( N o. 529 / 530), we discuss n o t o nl yw hy p e o ple ch o ose to live in thewild la n d / u r ban inte rfa ce (WUI), the term tha thas been applied to the area where the bu il te nvi ro n m e n t and fo rest s or grassla n ds i n te r-m i ng le, bu t h ow co m m un i t i esa re re visi ng theirpla ns and zo n i ng co d es to mitiga te the prob-lem. T h is issue of Zoning Practice p rovi d es ap re view of our findings with rega rd to zo n i ng.

HOW ZONING APPLIESBoth zoning and subdivision ordinances canaddress wildfire hazards by implementing anumber of policy options to curb the problem.

ZONINGPRACTICE 3.05AMERICAN PLANNING ASSOCIATION | page 2

This subdivision has only one access route. Residents could be trapped if a wildfire closedoff the entry road.

as well as a series of appendices that allowthe assessment of wildland fire risk for a par-ticular home or subdivision. States adoptingits provisions include Florida, California, andWashington, but states as diverse asPennsylvania, Montana, North Carolina,Colorado, Minnesota, and New Mexico use thehazard assessment checklist as the basis fortheir local risk and vulnerability assessmentactivities. Hundreds of local governmentshave also adopted it by reference or withadaptations, or use the hazard assessmentchecklist. A searchable National WildfirePrograms Database at www.wildfirepro-grams.usda.gov/ offers full references.

The model describes a multiagency oper-ational plan for the protection of lives andproperty during a wildfire, which goes beyondthe typical land-use and building require-ments in most ordinances regarding wildfire.The operational plan must contain command,training, community notification and involve-ment, and evacuation and mutual assistanceelements. These elements ensure a coordi-nated response among the various agenciesand organizations, including fire departments,social service agencies, the local media, andlaw enforcement in responding to a wildfire.

The ICC code covers administration, defi-nitions, WUI areas and requirements, specialbuilding construction regulations, fire protec-tion requirements, and referenced standards.Communities around the country adopt thecode, often with minor modifications to reflectlocal conditions. The local legislative bodydesignates the WUI area within its jurisdictionbased on findings of fact concerning climate,topography, vegetative character, and othercharacteristics affecting the area. The coderequires the area to be recorded on maps and

From April 18 to 29, go online to participate in our “Ask the Author” forum, an interactive fea-ture of Zoning Practice. Jim Schwab, AICP, and Stuart Meck, FAICP, will be available to answeryour questions about this article. Go to the APA website at www.planning.org and follow thelinks to the Ask the Author section. From there, just submit your questions about the articleusing an e-mail link. The authors will reply, posting the answers cumulatively on the websitefor the benefit of all subscribers. This feature will be available for selected issues of ZoningPractice at announced times. After each online discussion is closed, the answers will besaved in an online archive available through the APA Zoning Practice web pages.

About the AuthorsJim Schwab, AICP, is a senior research associ-ate for APA and served as the project man-ager for Planning for Wildfires. Stuart Meck,FAICP, is senior research fellow with APA andthe co-author, with Jim Schwab, of the newPAS Report, which can be ordered throughAPA’s Planners Book Service.

filed with the local government clerk. The codeofficial must reevaluate and recommend mod-ification to the interface area at least onceevery three years, or more often if necessary.Under the code, a permit is required for build-ings or structures in the area, unless the activ-ity is covered by permits issued under thebuilding or fire code. A variety of plans accom-pany the permit application: a site plan show-ing, among other things, topography, vegeta-tion, types of ignition-resistant buildingconstruction, and roof classifications; a vege-tation management plan; and a fire protectionplan, where required by the code official.

tion water sources, existing building construc-tion materials, and utilities, the code officialcan establish whether the hazard is moderate,high, or extreme.

FLORIDA MODEL ORDINANCEThe sta te of F l o r i da has pu bl ished an anno-ta ted model wild f i re mitigation ord i na n ce aspa rt o f a ma n u a l on best p ra c t i ces. Itfo cus es on ris k reduction in defined wild f i reha za rd areas. The ord i na n ce assi g ns ad m i n-ist ra t i ve and enfo rce m e n t resp o nsi bil i t i es toa wild f i re mitigation officia l. A wild f i re miti-gation re view boa rd, which app o i n t s the offi-cial, serves as an app e lla te body for affe c te dla n d ow n e rs who wish to app ea l the officia l ’ sa c t i o ns. The ove r lay d ist r i c t reg ula t i o ns a rea ppl i ca ble to la n d - use cha nges, su b d i vi-si o ns, si te pla ns, bu ild i ng permits, and allsp e cia l use permits, incl u d i ng co n d i t i o na lus es and va r ia n ces .

This model does not contain standardsfor identifying the WUI or high-risk areaswithin the interface. Rather, it states that theWUI delineation must be based on findings offact and the high-risk areas be based on dataobtained from the Florida Wildfire RiskAssessment, the state-published WildfireHazard Assessment Manual for FloridaHomeowners, or any study “supported bycompetent and substantial evidence.”

While the standards for fuel reductionand defensible space maintenance are similarto other wildfire ordinances reviewed, severalinteresting provisions in this model deserveconsideration for application elsewhere:

■ Provisions for tree protection. For co m m un i-t i es t ha t m i g h t ha ve tree pro tection ord i-na n ces t ha t wo uld otherwise re q u i re loca lgove r n m e n t p e r m ission to re m ove a tree, the

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Urban-Wildland Fuel ModificationInterface Area Distance (in feet)

Moderate hazard 30

High hazard 50

Extreme hazard 100

Source: International Code Council

The code uses a sliding distance scale,linked to the severity of the fire hazard, in set-ting standards for defensible space aroundnew and existing structures. A “defensiblespace” is an “area either natural or manmade,where material capable of allowing a fire tospread unchecked has been treated, cleared,or modified to slow the rate and intensity ofan advancing wildfire and to create an area forfire suppression operations to occur” (Chapter2, Section 202). The code official is responsi-ble for determining the nature of the severity.Appendix G of the code contains a fire hazardrating form incorporated into the code for thispurpose. By evaluating subdivision design,vegetation, topography, roofing, fire protec-

o rd i na n ce wa i ves t h ose permit re q u i re m e n t sw h e re the tree is a highl y f la m ma ble na t i ve oro r na m e n ta l t ree as l isted in the ord i na n ce ,and there fo re it is ve ry d esi ra ble to re m ove it.L i ke other wild f i re ord i na n ces, it go es on toi d e n t i fy a series o f re commended re pla ce-m e n t t re es t ha t a re less f la m ma ble .

■ Public disclosure and education. Themodel requires selling landowners, devel-opers, and Realtors to disclose in writingthe fact an undeveloped property is withina high-risk area or an overlay district as wellas the wildfire risks and potential nui-sances posed by fuel management activi-ties, including but not limited to the smokeproduced by prescribed burning activities.Under these provisions, the wildfire mitiga-

d ra ma t i c i n ce n t i ve is a la n d owner awa rdsp ro g ram in which the loca l gove r n m e n t re co g-n i zes la n d ow n e rs who ha ve un d e rta ke nn o ta ble wild f i re mitigation pro g rams.

The Florida ma n u a l a lso co n ta i ns a modelvege tation ma na ge m e n t o rd i na n ce tha t re q u i resa ny p e rson ow n i ng, leasi ng, or co n t roll i ng anyland upon or ad ja ce n t to wild la n ds to re d u ceb r ush aro und st r u c tu res in the WUI in order toesta bl ish an effe c t i ve fu e l b rea k and to ta keother actions, su ch as ke e p i ng the ro o f and gut-te rs f ree of f la m ma ble deb r is. If a vi olation isfo und, the vi ola tor has 60 days to co r re c t t h ep roblem, or the loca l gove r n m e n t may co r re c tthe vi olation and ass ess the pro p e rt y owner andesta bl ish a lien on the pro p e rt y un t il paid.

■ a map of the areas to be thinned to reducethe interlocking canopy of trees;

■ a tree management plan showing the loca-tion of all trees to be preserved andremoved on each lot. In the case of heavilyforested parcels, only trees scheduled forremoval shall be shown;

■ the areas of primary and secondary fuelbreaks required to be installed around eachstructure [as required by the code]; and

■ roads and drive ways su f f i ci e n t for emerge n c yve h i cle access and fire su pp ression activi t i es ,i n cl u d i ng the slope of a ll roads and drive-ways within the wild f i re la n ds a rea .

The hearing authority has the discretionto approve the plan and to impose conditionsincluding:

■ d e l i n eation of a reas o f h ea v y vege tation to bethinned and a fo r ma l plan for su ch thinning ;

■ clearing of sufficient vegetation to reducefuel load;

■ removal of all dead and dying trees; and

■ relocation of structures and roads to reducethe risks of wildfire and improve thechances of successful fire suppression.

The plan must be imple m e n ted befo rebu ild i ng permits a re issued. For su b d i visi o ns ,p rovisi o ns for ma i n te na n ce of the plan must b ei n cluded in the cove nants, with the ci t y na m e das a beneficia ry o f the cove nants, rest r i c t i o ns ,and co n d i t i o ns. For pa rt i t i o ns, the pro p e rt yowner is resp o nsi ble for ma i n ta i n i ng the pla n .

All new construction and any construc-tion expanding the size of an existing struc-ture must have a fuel break. A primary fuelbreak extends a minimum of 30 feet from allstructures or to the property line, whichever isless, in order to remove ground cover that willproduce flame lengths in excess of one foot.The regulations require the fuel break’s depthto be increased by 10 feet for each 10 percentincrease in slope over 10 percent. Where sur-rounding landscape is owned and under thecontrol of the property owner, a secondaryfuel break extending 100 feet beyond the pri-mary fuel break must be provided.

HAYWARD, CALIFORNIAHayward’s WUI guidelines contain construc-tion standards that apply to certain areas ofthe Hayward Hills that the city’s fire depart-ment has designated as “urban/wildland

This Gyrotrac is removing heavy fuels in an undeveloped lot in the Palm Coast subdivision inFlager County, Florida.


tion official is to conduct public work-shops, publish informational brochures,and make public announcements via theInternet and in written form on the risksposed by wildfires and the steps to betaken to mitigate potential damage.

■ I n c e n t i v e s . The ord i na n ce re q u i res the loca lgove r n m e n t to gra n t a one-time ad va l o re mta x exemption tha t a ppl i es to all i m p rove-m e n t s to rea l p ro p e rt y made by or for thepu r p ose of wild f i re mitigation and co m-ple ted in acco rda n ce with the app roved wild-f i re mitigation plan app roved by the officia l.In some sta tes, it may be necessa ry to ha veclear sta tu to ry a u t h o r i t y for the loca l gove r n-m e n t to gra n t su ch exce p t i o ns. Another less

ASHLAND, OREGONAshland, Oregon, has established a series ofdevelopment standards that apply to prelimi-nary plats and applications to partition landthat contains designated wildfire areas. Suchdevelopments trigger the preparation of a “fireprevention and control plan” as part of theapplication process. These are reviewed bythe fire chief as part of the record of theaction. Such a plan must contain:

■ an analysis of the fire hazards on the sitefrom wildfire, as influenced by existing veg-etation and topography;

■ a map showi ng the areas to be clea red ofd ead, dyi ng, or seve re l y d is eased vege ta t i o n ;

Florida Department of Agriculture and Consumer Services, Division of Forestry, from Wildfire Mitigation in Florida, page 93.

Codes affecting development in the WUI may propose the planting of fire-resistive vegetation,which burns at a relatively low intensity and has slow rates of spread with short flame lengths.Characteristics of such vegetation include:

■ Growth with little or no accumulation of dead vegetation, either on the ground or standingupright

■ Nonresinous plants, such as willow, poplar, or tulip trees

■ Low volume of total vegetation, such as a grass area as compared to a forest or shrub-cov-ered land

■ Plants that contain a large amount of water in comparison to their dry weight

■ Drought-tolerant plants—deeply rooted plants with thick, heavy leaves

■ Stands of plants without ladder fuels—fine, small branches and limbs between the groundand the canopy of overtopping shrubs and trees

■ Plants requiring little maintenance

■ Plants with woody stems and branches that require prolonged heating to ignite

Source: International Code Council (ICC), International Urban-Wildland Interface Code

CHARACTERISTICS OF FIRE-RESISTIVE VEGETATIONinterface zones.” According to the guidelines,these are areas that will typically includedevelopment sites adjoining steep slopes,open grasslands and brush lands, woodlandand riparian zones, or major drainage swales.In such areas, existing vegetation may causestructures to be exposed to rapidly spreadingfire that is difficult for the Hayward firedepartment to control.

Hayward’s guidelines differ according tostructure categories. Category I structures arethose located on sites where “maximum built-in fire protection measures are necessary dueto nearby steep slopes or wildland fuel load-ing.” These structures are to exceed minimumState of California Fire Safe Guidelines.Category II structures are those located in thebalance of the WUI. These meet minimumCalifornia guidelines. Hayward’s fire depart-ment designates which sites or lots mustcomply with either set of standards. In somecases, developers may be required to obtain,at their expense, a qualified WUI fire manage-ment consultant to assist in this designation.

The guidelines address both construc-tion standards and fuel management.Building construction standards, listed below,can be applied either to Category I or II struc-tures, or both.

1. Enclose all roof eaves (I).

2. Provide double-paned windows for exteriorwindow (I).

3. Specify a one-hour fire-resistive rating orgreater for exterior building material (I).

4. Within 10 feet of a structure, constructfences with an open wire mesh or noncom-bustible material to prevent fire fromspreading to the structure (I).

5. Design roofs that comply with a “Class A”noncombustible roof rating as outlined in[California] State Building Code Section3202, 1991 edition (do not use wood shakeor treated wood shake roofs) (I & II).

6. Provide metal enclosures with one-quarterinch metal mesh screens on all attic vents(side vents) and basement vents (I & II).

7. P rovide spa r k a r resto rs with one-quarter inchm esh scre e nson all ch i m n e ys. (I & II).

The guidelines call for the establishmentof a fuel management program and recom-mend that, if feasible, the program be imple-mented by a homeowners associationthrough covenants and restrictions applicable

to the development, not individual home-owners. The program is to consist of:

1. Homeowner education. This includespreparation of a pamphlet on fire safety,the fire cycle, and the ecological factorsrelated to fire.

2 . A shaded fuel break. T h is i n te r r u p t s the fireladder or the tra ns fer of f i re from the gro un d( via shrubs and gro und cove rs) to tre eca n o p i es. In su ch an area, brush and sele c te dun d e rsto ry a re re m oved from the gro und, andl ower limbs o f t re es a re pruned ba ck .


3. “Mosaic islands” of brush and shrubs. Insuch areas, stands are selectively thinned—from 60 to 70 percent removed—to reducefuel loading and break up the continuity ofthe fuel bed.

4 . Fire-resistant plants for domestic andreplacement planting. The guidelines re co m-mend a series o f sp e ci es .

5. Establishment of fuel management zones.The guidelines propose four levels of zonesto limit the exposure of a structure to radi-ant heat and debris from an advancing fire.

( A b ove) Fu e l b reak, befo re and after; (below) mosa i c isla n ds .

Zone 1 is the minimum 30-foot firebreakimmediately adjacent to the house or struc-ture limited to fire-resistant species, treeswith high canopies, and low-growingshrubs and ground covers. The guidelinescall for the annual removal of dead leavesand the installation of an automatic irriga-tion system for domestic landscaping dur-ing hot, dry periods. Zone 2 is an addi-tional firebreak of 70 feet or more that maybe required depending on the fire depart-ment’s judgment on the sufficiency of ZoneI. Zone 3 is a fuel break transition zone.Here domestic plants should be low-grow-ing, slow-burning, and low-volume speciesthat blend with the landscape and requireno water once established. Zone 4 is natu-ral open space where fuels have been mod-ified through shaded fuel breaks andmosaic islands to reduce fuel loading, fuelcontinuity, and fire ladders. Where a road-way abuts open space in such a zone, theguidelines recommend reducing or modify-ing vegetation for a minimum distance of10 feet from the roadway.

PRESCOTT, ARIZONA Prescott has adopted the ICC model code butmodified some of its language to fit thespecifics of its area and to add detail to cer-tain sections. For example, the ICC code callsfor the local government to incorporate find-ings of fact that serve as a justification for thedesignation of wildland areas. One of theaspects of the findings is to designate a spe-cific fuel model—a description of the mix ofpotentially flammable vegetative materials.The nature of the fuel model affects the flame

length and rate of spread, as described in thePrescott code:

The seasonal climatic conditions during thelate spring and early summer create numer-ous serious difficulties regarding the controlof and protection against fires in the City ofPrescott.

Average maximum temperatures of 88.9degrees in July

Relative humidity: 10 to 15 percent in Mayand June

Twenty-eight days of extreme fire weatherconditions from end of April through July

Live fuel moisture in chaparral from 61.8 per-cent in April to 86.4 percent in August.(Anything under 80 percent will burn)

Fu e l m o istu re in 1,000-hour fu e ls is 5 perce n t

Winds: 35 to 40 miles per hour

Numerous dry lightning strikes

Prescott has predominantly fuel model 4(chaparral), which is found in all of the “atrisk neighborhoods.” This includes oakbrush (scrub oak) and manzanita.

Utilizing fuel model 4 scenarios as an exam-ple, the rate of spread could be 721 feet perminute. The flame lengths could be 57 feethigh. Burning brands can jump ahead of thefire for a distance of 2.1 miles and igniteadditional fires. The fire could consume5,641 acres in one hour and spread a dis-tance of 8.1 miles. The perimeter of the firewould be 90,321 feet. This type of fire isuncontrollable by the on-duty fire forces dueto lack of staffing and lengthy responsetimes. This fire could result in a major struc-tural conflagration. The fire could spreadacross the Prescott Basin at the interface.

Fu rt h e r, the Presco t t code ampl i f i es t h ere q u i re m e n t s for the vege tation ma na ge m e n tplan. The code re q u i res t ha t the modification ofvege ta t i ve fu e l — re m ova l o f slash, sna gs, otherg ro und fu e ls, ladder fu e ls, and dead tre esa n d

the thinning of l i ve tre es — within 30 fe e t o f t h eh o use or to the pro p e rt y line, which e ver is less ,be co m ple ted prior to any ve rt i ca l co nst r u c t i o n .Be yond 30 fe e t and up to 150 fe e t o f the hous eor pro p e rt y line, the vege ta t i ve fu e l m o d i f i ca-t i o nsm ust be co m ple ted befo re a ce rt i f i ca te ofo ccu pa n c y can be issu e d .

The code details requirements for thedefensible space surrounding the structure. Itprescribes the following defensible spacepractices:

■ Decreasing the amount of flammablevegetation

■ Increasing the amount of open space

■ I n creasi ng the moistu re co n te n t o f vege tation

■ Planting less flammable plants

■ Rearranging existing plants

■ Reducing trees to a maximum of 200hydrated or 85 nonhydrated, healthy treesper acre with understory pruned and main-tained

■ Removing all combustible materials andvegetation from under decks

■ Continuing maintenance of the area

■ Maintaining the defensible space require-ments by the homeowners associationand/or owner of the property.

PINETOP-LAKESIDE, ARIZONAThe Pinetop-Lakeside code relating to foresthealth and fire protection contains detailedguidance on the establishment of a three-zone plan to satisfy the defensible spacerequirements on all parcels where there is abuilding or structure and for vacant parcels ofless than two acres. The code describes a setof mandatory and recommended actions forproperty in each zone. Most notable is thereduction of tree density through on-site thin-ning to lower risk from fires.

A. Zone 1: Zero feet to 10 feet from build-ings, structures, decks, etc.

1. Required Zone 1 Fuel Modification:

a . Re m ove fu e l ladd e rs a n dre d u ce non-fire - resista n tb r ush, lea vi ng prima r il y f i re -resista n t sp e ci m e ns.

b. Remove and destroy all insect-infested, diseased, and deadtrees to prevent spread tohealthy vegetation.


Fu e l ma na ge m e n t zo n es .

Cover photo by James Smalley. Photoshows an area in Bel Air, California, wherea massive wildfire occurred in 1961 beforebeing rebuilt.

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“ Basa l a rea” is a measu re m e n t o f t re ed e nsi t y. The basa l a rea is the cross -s e c t i o na l a rea of a tree 4.5 fe e t a b oveg ro und. The basa l a rea of a ll t re es in ag i ven land area descr i b es the deg re eto which an area is o ccupied by t re esand is ge n e ra ll y ex p ressed in sq u a refe e t per acre. The basa l a rea ca l cula-tion is: X2 m ul t i plied by .0 0 5 45 4 ,w h e re X e q u a ls t ree dia m e ter in inch esa t 4 .5 fe e t a b ove gro und, or dia m e te ra t b reast h e i g h t (dbh). For exa m ple ,the basa l a rea of a 12-inch dbh tree isca l cula ted as foll ows: 122 x .0 0 5 454 =.7854 sq u a re fe e t.

So u rce: Ci t y o f P i n e to p - L a keside Co d e

c. Remove all dead plant materialfrom the ground that may createfuel ladders or contribute to thespread of fire.

d. Where applicable, trim conifer-ous trees to where the lowestbranches or canopy are abovethe roofline and a minimum of10 feet from chimneys or othersources of ignition.

e. Remove flammable debris fromgutters and roof surfaces.

f. Re m ove all co m bust i ble ma te r i-a ls and vege tation from un d e rd e cks. Non-fire - resista n t vege-tation within three fe e t o f bu ild-i ngs, st r u c tu res, and deckss h o uld be spa ced to limit i g n i-tion from su r ro un d i ng vege ta-tion and the creation of fu e lladd e rs.

2. Recommended Zone 1 FuelModification:

a. Defensible space should be reg-ularly maintained during periodsof high fire danger.

b. Provide adequate hydration forall vegetation.

B. Zone 2: Ten feet to 30 feet from build-ings, structures, decks, etc.


a. Remove all ladder fuels anddead material.

b. Remove and destroy all insectinfested, diseased, and deadtrees to prevent spread tohealthy vegetation.


a. Zone 2 defensible space shall bemaintained at least annually.

b. Create separation between trees,tree crowns and other plantsbased on fuel type, density,slope, and other topographicalconditions that may adverselyaffect fire behavior.

c. Reduce continuity of fuels by cre-ating clear space around brushor planting groups.

d. Control erosion and sedimenta-tion from exposed soils throughterracing, gravel beds, rocks, orother appropriate ground cover.Emphasis is placed on slopesgreater than 20 percent gradient,in which case, additional vegeta-tion treatment may be required.

e. Remove all but one inch of pineneedle or leaf droppings. It isimportant to leave a layer ofdecomposing plant material tomaintain adequate moisture lev-els for further decompositionand plant hydration.

C. Zone 3: Thirty feet to 100 feet frombuildings, structures, decks, etc. whereslopes do not exist and undevelopedlots are less than two acres.


a. Remove all ladder fuels and deadmaterial.

b. Thin coniferous trees to achievean overall average density of notmore than 100 trees or 60square feet basal area per acre.

c. Remove and destroy all insectinfested, diseased, and deadtrees to prevent spread tohealthy vegetation.


c. Zone 3 defensible space shouldbe maintained at least annually.

CONCLUSIONA s la rger numbers o f p e o ple ha ve sought t h esce n i c and na tu ra l a m e n i t i es o f l i vi ng in thewild la n d / u r ban inte rfa ce, pla n n e rs in co m-m un i t i es fa ci ng wild f i re ha za rds ha ve fa ce dan increasi ng need to dra ft and imple m e n treg ula t i o ns t ha t can dire c t su ch deve l o p-m e n t to app ro p r ia te loca t i o ns and to mini-m i ze the ha za rds for those livi ng there. T h e ya lso fa ce a growi ng need to become know l-e d gea ble about w ha t has wo r ked and wha td o es n o t. Although models exist for cra ft i ngsu ch reg ula t i o ns, the na tu re and the sco p eo f the ha za rd will be diffe re n t in eve ry co m-m un i t y, so model co d es m ust be ada p ted tol o ca l ci rcu m sta n ces. Howe ve r, as the newPA S Re p o rt d o cuments, it is p ossi ble toe nl ist pu bl i c su pp o rt t h rough education andthe dire c t i nvol ve m e n t o f resi d e n t s toa ch i e ve wo r ka ble and effe c t i ve sol u t i o ns .

models for mitigating wildfire hazards through zoning · the essentialissue in wildfire hazard...

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