water mgmt : flashing

August 24, 2006Eppstein Uhen Architects 1

Water Management F L A S H I N G

p r e s e n t a t i o n


Presentation OutlineI. Water Management System (WMS)

A. Nature of WaterB. WMS Components

II. Exterior Shell PerformanceA. RoofingB. Walls

III. WMS Focus: FlashingA. Flashing TypesB. Roof FlashingC. Wall Flashing

IV. Conclusions


Water Management SYSTEM

I. Water Issue? A. Knee jerk reaction: Blame the FLASHING

II. While researching FLASHING, other WMS components always mentioned:

A. Air and Vapor Barriers B. Heat Barrier C. Water Barrier


Water Management SYSTEMI. WMS Presentations

A. Part I: Flashing (PM Workshop)

B. Part II: Water Barriers (PM Workshop)

C. Part III: Air/Vapor/Heat Barriers (PM Workshop)

D. Part IV: WMS Detailing (Studio Workshops)i. Masonry Wallsii. Veneer Systemsiii. Wood Construction


WMS: Nature of Water

I. (3) Physical States of H20A. Liquid (water) B. Vapor (gas)C. Solid (ice)

II. Sources of MoistureA. Liquid/Solid:

i. Precipitation (Rain, Sleet, Snow)ii. Condensation

B. Vapor: i. Artificial Humidificationii. Relative Humidity


WMS: Nature of WaterI. Driving Forces for Rainwater Penetrations

A. Gravityi. Draw water down thru openings into assembly

B. Surface TensionC. Capillary Suction

i. Sucks water thru cracks/poresD. Momentum

i. Pass thru openings in exterior claddingE. Air Pressure Differential

i. Push/pull water thru cracks/pores


WMS: Components

I. Air and Vapor Barriers

II. Heat Barrier

III. Flashing

IV. Water Barrier


WMS: Air & Vapor Barriers (AVB)

I. Most materials are effective AIR Barriers

i. Needs to be continuousa. Intersections between wall/roof, floors, foundationb. Interface of wall assembly & door/window/curtain wallsc. Penetrations thru ABd. Joints/seams between sheets/boards of AB

II. Few materials are complete VAPOR Barriers

i. Place on warm side (winter) of Heat Barrier (insulation)a. Vapor arrested before it reaches colder surfacesb. Moist, warm air moves TO cooler, dryer air

III. More accurate description: Vapor Retarders


WMS: Components


II. Heat Barrier

III. Flashing

IV. Water Barrier


WMS: Heat Barrier (Insulation)

I. Heat TransferA. Decrease as the wall’s thermal

resistance increases

II. R-Value: thermal resistance

III. Common pitfallsA. Inappropriate locationB. Discontinuity

i. Thermal bridgingC. Dewpoint

i. Condensation & staining issues


WMS: Components


II. Heat Barrier

III. Flashing

IV. Water Barrier


WMS: Flashing

I. Main Causes of Moisture Intrusions

A. Interface detailsi. Bldg envelope penetrations

a. Decksb. Windowsc. Doors

B. Flashingi. Did not exist OR were not integrated

with the rest of the WMS


WMS: Components


II. Heat Barrier

III. Flashing

IV. Water Barrier


WMS: Water Barrier (WB)I. Forms vertical surface behind cladding

A. Allows water to drain out of the wall system

II. Exterior cladding protects WBA. WeatherB. Ultraviolet (UV) Radiation

III. Lets wall components dry safetyA. Allows internal vapor to escape out

IV. Most important deterrent against liquid water penetrating INTO the bldg enclosure

A. Acts as a barricade - Continuous & shingled


WMS: ComponentsI. Map out the PASSAGE of water

A. Drainage Spacei. Allows free drainage of water

B. Drainage Planei. Water Barrier (WRB)

a. Overlappingb. Integrating w/flashing

C. Flashings

D. Weep Holesi. Located DIRECTLY above flashing


Exterior Shell Performance

I. Continual expansion & contractionA. Moisture content + Thermal

II. Corrosion: Metals A. Electrolytic action causes a current to flowB. Water is the electrolyte to complete the circuitC. Electronic potential:

i. Metal A + Metal Bii. Metal A + Water + Salt

D. Example: Storing planes in the desert

III. Decay: WoodA. Food (wood) + water + air+ temperatureB. Example: Submerged trees in water

IV. Efflorescence: MasonryA. Migrating water dissolves salts inside material and deposits them

on it’s surface

V. Leaching: Concrete & MortarA. Leaching out the calcium from the calcium chloride



I. (3) Types of Exterior Wall Design

A. Face-Sealed Barriersi. EIFS (non-drainable)ii. Curtain Walls (face-sealed)

B. Concealed Barrier Wallsi. Stucco system (drainable)ii. EIFS (drainable)

C. Drain Cavity or Rain Screeni. Brick-veneer cavity wallsii. Furred-out clapboard wallsiii. EIFS (drainable w/membrane)


Exterior Shell PerformanceI. Face-Sealed Barriers

A. Every seam/crack is sealedB. Requires detailed workmanshipC. Requires continuous

maintenanceD. Most vulnerable to rain

infiltrationE. Effective in areas with:

i. Low wind and low rain exposure



I. Concealed Barrier WallsA. Relies on multiple layers for rain penetrationB. Provides (2) lines of defenseC. Drainage plane in the wall assembly

i. Usually a water-resistive barrier membraneD. Requires continuous maintenanceE. Effective in areas with:

i. Moderate wind and moderate rain exposure



I. Drain Cavity or Rain ScreenA. Relies on (2) layers + drained cavity for rain penetrationB. Provides (2) lines of defenseC. Drainage plane in the wall assembly

i. Usually a water-resistive barrier membraneD. Additional features:

i. Capillary break between porous materialsii. Freer drainageiii. Venting limits relative humidity (RH) outboard of sheathing

E. Effective in areas with:i. High wind and high rain exposure



I. Drainage Wall System



I. Enclosure Performance depends on:

A. Proper Sequencingi. Exposure Duration

B. Detailingi. Spec vs. Drawingsii. Field vs. Pre-fab

C. Construction Material’s Recoveryi. Ability to get wet and then dry outii. Not deteriorate or contaminate (microbes)


Flashing - TypesI. Sheet Metals

A. Stainless SteelB. Galvanized SteelC. Copper (Cold Rolled)D. Copper (Lead-Coated)E. Aluminum

II. Composite MaterialsA. Copper LaminatesB. Aluminum LaminatesC. Lead Laminates

III. FabricsA. PVCB. Rubberized AsphaltC. EPDM


Flashing – Sheet MetalsI. Advantages

A. Extend beyond face of wall i. Forms drip edge – conducts water out

B. May be solderedi. Mastics or sealants need not be solely relied upon

C. Stiffness allows for proper geometriesD. Can be exposed to weatherE. Suitable substrate for construction sealants

II. DisadvantagesA. More expensive than membrane flashingB. Aluminum corrodes in an alkaline environment

i. Masonry Mortar ii. Concrete


Flashing – Composite/Fabrics

I. AdvantagesA. Less expensive than metal flashingB. Self-sealing properties

II. DisadvantagesA. Must be continuously supported

i. To avoid creating water pocketsii. To provide a solid substance for proper seaming

B. Relies on field installeri. Bed & seal membrane (transverse seams)ii. Unsuitable substrate for common construction sealants

C. Exposure issues: degradation due to sunlighti. Must terminate at/inboard of wall faceii. This encourages water bypass at front edge of membrane


Flashing – ConsiderationsI. Main Criterion: Expected Life

A. Flashing MUST last as long as life of building

II. CostA. Material CostB. Installation CostC. Maintenance Cost

III. InstallationA. Ease of InstallationB. Ease to JoinC. Ease of Fabrication

IV. PerformanceA. Compatibility with materialsB. Resistance to punctures/tearsC. Resistance to UVD. Resistance to Corrosion

Flashing with Metal Drip Edge


Flashing – ComparisonS

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THICKNESS (MIN) 0.01" 0.015" 10 oz/ft210 oz/ft2 X 5 oz/ft2 ? ? 30 mils 30 mils 30 mils

A) COSTMaterial Cost 2 2 1 1 2 2 3 3 5 5 4Installation CostMaintenance Cost

A) Subtotal 2.0 2.0 1.0 1.0 2.0 2.0 3.0 3.0 5.0 5.0 4.0RATINGS

0: Not Applicable1: Very High2: High3: Average4: Low5: Very Low

B) INSTALLATIONEase of Installation 1 2 2 2 3 4 4 4 5 5 5Ease to Join 1 1 3 2 2 3 3 3 4 5 4Ease of Fabrication 2 1 3 2 2 3 3 3 4 4 4

B) Subtotal 1.3 1.3 2.7 2.0 2.3 3.3 3.3 3.3 4.3 4.7 4.3RATINGS

0: Not Applicable1: Very Difficult2: Difficult3: Average4: Easy5: Very Easy

C) PERFORMANCECompatibility with materials 3 3 2 2 2 2 2 2 1 2 2Resistance to punctures/tears 4 5 3 3 4 2 3 3 1 2 2Resistance to UV 5 5 5 5 5 3 3 3 1 2 3Resistance to Corrosion 5 3 4 4 5 3 3 3 4 4 4Expected Life 4 4 5 5 4 3 3 3 2 4 4

C) Subtotal 4.2 4.0 3.8 3.8 4.0 2.6 2.8 2.8 1.8 2.8 3.0RATINGS

0: Not Applicable1: Very Poor2: Poor3: Average4: Good5: Very Good

COMMENTS1. Corrodes in fresh mortar ?2. Non-staining ? ? ? ? ? ? ? ?3. Requires metal drip edge ? ? ? ?4. Self-sealing if puntured ?5. Full-support required ? ? ?

TOTAL (1:Low 5:High) 2.5 2.4 2.5 2.3 2.8 2.6 3.0 3.0 3.7 4.2 3.8

SHEET METALS COMPOSITE MATERIALS FABRICS

DESCRIPTION

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THICKNESS (MIN) 0.01" 0.015" 10 oz/ft210 oz/ft2 X 5 oz/ft2 ? ? 30 mils 30 mils 30 mils

A) COSTMaterial Cost 2 2 1 1 2 2 3 3 5 5 4Installation CostMaintenance Cost

A) Subtotal 2.0 2.0 1.0 1.0 2.0 2.0 3.0 3.0 5.0 5.0 4.0


DESCRIPTION

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B) INSTALLATIONEase of Installation 1 2 2 2 3 4 4 4 5 5 5Ease to Join 1 1 3 2 2 3 3 3 4 5 4Ease of Fabrication 2 1 3 2 2 3 3 3 4 4 4

B) Subtotal 1.3 1.3 2.7 2.0 2.3 3.3 3.3 3.3 4.3 4.7 4.3


DESCRIPTION

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C) PERFORMANCECompatibility with materials 3 3 2 2 2 2 2 2 1 2 2Resistance to punctures/tears 4 5 3 3 4 2 3 3 1 2 2Resistance to UV 5 5 5 5 5 3 3 3 1 2 3Resistance to Corrosion 5 3 4 4 5 3 3 3 4 4 4Expected Life 4 4 5 5 4 3 3 3 2 4 4

C) Subtotal 4.2 4.0 3.8 3.8 4.0 2.6 2.8 2.8 1.8 2.8 3.0


DESCRIPTION

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TOTAL (1:Low 5:High) 2.5 2.4 2.5 2.3 2.8 2.6 3.0 3.0 3.7 4.2 3.8


DESCRIPTION


WMS: Flashing – Where?I. Where Water Barriers (WB) terminateII. B30 Roofing

A. B3010 Roof CoveringsB. B3020 Roof Openings

III. B20 Exterior ClosureA. B2010 Exterior Walls

i. Top of exterior walls & parapetsii. Base of exterior wallsiii. Penetrations through the wall assemblyiv. Shelf angles (cavity walls)

IV. B2020 Exterior Windows / B2030 Exterior Doors

i. Perimeters of openings: Head, Sill, & JambV. A10 Foundations (exposed)


Flashing: Roofing – Where?

I. TerminationsA. Expansion joints

II. JunctionsA. Examples:

i. Penthousesii. Skylightsiii. Chimneysiv. Equipment Housingv. Parapets

B. Thru-wall needs to lead water out of the wall

C. Parapets: exposed on exterior, interior and top


Flashing: Roofing – Where?

III. PenetrationsA. Examples: pipes, ductsB. Group many into a single curbC. Differential movementD. If connected- flashing flexible

to move with itE. Minimize quantityF. Small pipes/ducts

i. Separate support for base flashing not used

ii. Sleeves (metal or plastic flanged): require frequent maintenance

iii. Counterflashing + coverIV. Joints


Flashing: RoofingI. Prevents water from penetrating exterior

surfaceA. Intercepts water at parapets, walls, penetrationsB. Diverts itC. Leads it out to the membraneD. Flows out to the roof drains

II. Think of roof membrane as one large flashing designed to hold water until drainage system takes over

III. Detail ComponentsA. Base flashingB. Counter-flashingC. Cap flashing

Concrete Roof Slab Dtl


Base Flashing (Roofing)I. Extension of the roof

membrane or a different material bonded to form a waterproof joint

II. Extends upward along vertical surface

III. Diverts water onto the membrane

IV. Pass over top of parapet or cant

A. Minimize of water leaking behind it

B. Liquid-applied: not suitablei. Cannot be carried over a

parapet/roof-wall jointC. Reach higher than water

could be “stored”


Counter-Flashing (Roof)I. Description

A. Carries water onto base flashing/membraneB. Covers vertical face of base flashingC. Secured to the parapet or wall claddingD. Not connected to base flashingE. Provides physical and UV protection for base

flashing F. Not expected to watertight

II. May not be required with some roofing types:

A. Modified bitumenB. Single-ply membranes

III. If not required, don’t include it A. Covers up defects & hinders maintenance

IV. Details requiring reglets should be avoided


Cap Flashing (Roof)I. Horizontal coverings for

parapets & expansion jointsII. Sloped toward roofIII. Secured to allow

differential movementIV. Not expected to watertightV. Provides physical and UV

protection for base flashingVI. Only aesthetic with some

roofing types:A. Modified asphaltB. Single-ply membranes


Cap Flashing (Roof)


Roof Flashing - SummaryI. Compatibility between base flashing & the

membraneII. Ease of right angle turns in built-up roofs

A. Cants prevents puncturing of flashing membranes

III. Differential movementA. Counterflashing and wall/parapet it is securedB. Roof deck and wall/parapet

IV. Failure of reglet sealsA. Caulk not maintainedB. Counterflashing moves


Flashing: Walls – Where?I. Critical Locations

A. Top of the Walli. Parapet

B. Openingsi. Headii. Silliii. Jamb

C. Through Walli. Shelf Angles

D. Base of Walli. Where wall rests on foundation


Flashing: Openings


Flashing: Head

Window Head Detail and Cavity Seal


Flashing: Head


Flashing: Window Lintel


Flashing Details - Sills


Flashing: Window Sill

Commercial aluminum window in metal stud with exterior gypsum board sheathing


Flashing: Window Sill


Flashing: Interruptions

Lipped Brick Detail


Flashing: Base of Wall



Base flashing with concrete wall backup and masonry veneer


Flashing: Coordination


Flashing: Critical DetailsI. Critical Details

A. Inner & Outer Cornersi. Field Fabricatedii. Preformed Corners

B. Lapping i. Horizontal – Flashingii. Vertical – Water Barrier

C. Terminations i. Drip Edgesii. End Dams

a. 6”-8” beyond jambD. Keep Air Space (AS) clean

i. Veneer (wood frame): 1” ii. Veneer (steel frame): 2” iii. Cavity (w/rigid insul): 1” iv. Cavity (w/no insul): 2” v. Cavity (w/rigid insul &

drainage panel): 0- 3/8”


ConclusionI. Water: BAD - Flashing: GOOD

II. Flashing Rules of ThumbA. ContinuityB. Extend past face of wall

i. Divert water OUTC. Seal top of flashing (water barrier)D. Protect flashing from punctures

III. Managing water with a SYSTEMA. Ounce of prevention = Pound of cureB. Initial cost < Future Repair / Liability


Conclusion

Questions???

Comments???

Concerns???

Suggestions???


Water Management F L A S H I N G

T H A N K Y O U


Detailing – Detail on CD’s


Detailing – Sequencing A


Detailing – Sequencing B


Detailing – Sequencing C


Detailing – Sequencing D


Detailing – Sequencing E


Detailing – Sequencing F


Detailing – Sequencing G


Detailing – Sequencing H


Detailing – Sequencing I