OFFICE OF BUILDING TECHNOLOGY, STATE AND COMMUNITY PROGRAMSENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY

Buildings forthe 21st CenturyBuildings that are moreenergy efficient, comfortable,and affordable... that’s thegoal of DOE’s Office of BuildingTechnology, State andCommunity Programs (BTS).To accelerate the developmentand wide application of energyefficiency measures, BTS:• Conducts R&D on technologies

and concepts for energy efficiency, working closely withthe building industry and withmanufacturers of materials,equipment, and appliances

• Promotes energy/money

saving opportunities to bothbuilders and buyers of homesand commercial buildings

• Works with state and local

regulatory groups to improvebuilding codes, appliance standards, and guidelines for efficient energy use

• Provides support and grants

to states and communitiesfor deployment of energyefficient technologies andpractices

As part of a whole

wall design, weather

resis

tive barriers need to be integrated with otherwall system components, including structure,insulation, vapor retarder, air retarder (if separate), and flashing systems.A comprehensive approach to water management prevents water from reaching the sheathing or framing. Primary water managementstrategies include water-shedding characteristics that include overhangs and exteriorcladdings. Secondary (redundant) water management usually employs a weather-resistivebarrier to protect the sheathing and framingfrom moisture damage.A weather-resistive barrier is a drainage plane. Itallows water that has penetrated past the sidingto drain away from the wall system. Buildingpaper or housewrap is usually used to form thebarrier. Attaching siding to furring strips provides an air gap between the siding andweather-resistive barrier that improves drainageand addresses related moisture issues.

wall systems that protect building materialsfrom exterior water penetration. They performlike a shell for buildings—liquid water that haspenetrated the exterior finish does not passthrough, yet water vapor can escape. By keeping building materials dry, a weather-resistivebarrier improves building durability, decreasesmaintenance costs, and reduces the risk ofmoisture-related problems such as bugs, mold,mildew, and rot. Some weather-resistive barriers also reduce air infiltration, cutting utilitycosts and increasing comfort.TYPES AND COSTS OF WEATHERRESISTIVE BARRIERSBuilding paper is a traditional paper sheet or feltmaterial that is asphalt coated or impregnated toincrease its strength and resistance to waterpenetration. It is primarily employed to protectagainst moisture as a drainage layer. Housewraprefers to spun-plastic sheet materials that arewrapped around a house to protect againstmoisture penetration. If properly sealed, housewrap can also serve as an air retarder to reduceinfiltration. In some wall systems, sealed waterresistive sheathing such as rigid foam board canserve as the weather-resistive barrier, eliminatingany need for building paper or housewrap.Building paper typically costs about $300, materialand labor, to cover a 2,500-square-foot home. Itusually comes in a 3-foot roll that one person caninstall. Housewrap costs about $450, materialsand labor, for the same size house. While it isavailable in 3-foot rolls, rolls are usually 9-feet wideand require two people for installation.

FURRED-OUT SIDING

1⁄2" Gap behind siding

Weather-resistive barrier

Sheathing

Siding

1⁄2" x 2" Strips

Studs and insulation

arriers make an effective air

eams and penetrations are

 appropriate sealant or tape.

 building paper is not a true

ousewrap air leakage rates

ury pressure differential) fall

0.08 CFM/ft2— the higher the

e airflow.

arriers vary in their resis

traviolet (UV) radiation, and

This is important in resisting

tion or under wind loading.

ghly resistant to tearing,

er.

V rays within sunlight will

g materials during the

ation process. Most building

sistant, whereas recom

 exposure limits vary widely

nufacturer).

e— Housewrap tolerates

ecause plastic does not

uilding paper absorbs mois

elp dry out water otherwise

10/29/00, 9:50 AM
Caulk underhousewrap andseal gap betweenelectrical boxand sheathing

Housewrap

Unroll around house

Seal spigot 

at opening

Modified “I”-cut, fasten flaps to the inside of the framing

dwich 

Tape

Caulk

space

  yy yy

Tapehousewrap

housewrap

AILS

nufacturer

approved tapes

s duct tape.

The modified “I”-cut wrap creates three flaps that are wrapped around the window opening

Create slits to slide head flashing and barrier strip underneath housewrap, fasten with nails, then tape the slits in the wrap

not cause damage. Details may vary with siding and windowtype and the installation sequence for the window, trim, andweather-resistive barrier. It is advisable to install window headand sill flashing, whether it is metal, plastic, or a self-stickingelastomeric membrane. Avoid relying on tapes or sealants to

The “I”-cut allows the vertical leg of head flashing to be placed

under the weather-resistive barrier and then taped or sealed.It is best to divert drainage onto the face of the weather-resistive barrier. Do not tape down or seal behind the bottom nailingflange of windows, as doing so could accidentally trap in water.

Barrier strips are attached with nails and overlapped with successive barrier strips and weather-resistivebarriers in shingle fashion. Do not depend on tapes or glues, as they may fail over time.Housewrap technique utilizes a modified “I”-cut in the material, which is then wrapped to the inside of

the window frame and fastened. The head flashing and barrier strip are fastened and “shingled” under a

flap that is cut in the wrap. These seams are then taped.

a a aaaaaaaa

1 Install lower barrier strip 

over weather-resistive barrier installed to underside of opening

2 Install side 

window barrier strips

3 Install window

4 Install head 

flashing and overlap with upper window barrier strip

5 Overlap 

successive weatherresistive barriers in shingle fashion

FLASHING WINDOW OPENINGS

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaa

10/29/00, 9:50 AM
Caulk underhousewrap andseal gap betweenelectrical boxand sheathing

Housewrap

Unroll around house

Seal spigot 

at opening

Modified “I”-cut, fasten flaps to the inside of the framing

ndwich 

Tape

Caulk

space

  yy yy

Tapehousewrap

housewrap

AILS

nufacturer

approved tapes

s duct tape.

The modified “I”-cut wrap creates three flaps that are wrapped around the window opening

Create slits to slide head flashing and barrier strip underneath housewrap, fasten with nails, then tape the slits in the wrap

not cause damage. Details may vary with siding and windowtype and the installation sequence for the window, trim, andweather-resistive barrier. It is advisable to install window headand sill flashing, whether it is metal, plastic, or a self-stickingelastomeric membrane. Avoid relying on tapes or sealants to

The “ I”-cut allows the vertical leg of head flashing to be placed

under the weather-resistive barrier and then taped or sealed.It is best to divert drainage onto the face of the weather-resistive barrier. Do not tape down or seal behind the bottom nailingflange of windows, as doing so could accidentally trap in water.

Barrier strips are attached with nails and overlapped with successive barrier strips and weather-resistivebarriers in shingle fashion. Do not depend on tapes or glues, as they may fail over time.Housewrap technique utilizes a modified “ I”-cut in the material, which is then wrapped to the inside of

the window frame and fastened. The head flashing and barrier strip are fastened and “ shingled” under a

flap that is cut in the wrap. These seams are then taped.

a a aaaaaaaa

1 Install lower barrier strip 

over weather-resistive barrier installed to underside of opening

2 Install side 

window barrier strips

3 Install window

4 Install head 

flashing and overlap with upper window barrier strip

5 Overlap 

successive weatherresistive barriers in shingle fashion

FLASHING WINDOW OPENINGS

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaa

10/29/00, 9:50 AM
OFFICE OF BUILDING TECHNOLOGY, STATE AND COMMUNITY PROGRAMSENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY

Buildings forthe 21st CenturyBuildings that are moreenergy efficient, comfortable,and affordable... that’s thegoal of DOE’s Office of BuildingTechnology, State andCommunity Programs (BTS).To accelerate the developmentand wide application of energyefficiency measures, BTS:• Conducts R&D on technologies

and concepts for energy efficiency, working closely withthe building industry and withmanufacturers of materials,equipment, and appliances

• Promotes energy/money

saving opportunities to bothbuilders and buyers of homesand commercial buildings

• Works with state and local

regulatory groups to improvebuilding codes, appliance standards, and guidelines for efficient energy use

• Provides support and grants

to states and communitiesfor deployment of energyefficient technologies andpractices

As part of a whole

wall design, weather

resis

tive barriers need to be integrated with otherwall system components, including structure,insulation, vapor retarder, air retarder (if separate), and flashing systems.A comprehensive approach to water management prevents water from reaching the sheathing or framing. Primary water managementstrategies include water-shedding characteristics that include overhangs and exteriorcladdings. Secondary (redundant) water management usually employs a weather-resistivebarrier to protect the sheathing and framingfrom moisture damage.A weather-resistive barrier is a drainage plane. Itallows water that has penetrated past the sidingto drain away from the wall system. Buildingpaper or housewrap is usually used to form thebarrier. Attaching siding to furring strips provides an air gap between the siding andweather-resistive barrier that improves drainageand addresses related moisture issues.

wall systems that protect building materialsfrom exterior water penetration. They performlike a shell for buildings—liquid water that haspenetrated the exterior finish does not passthrough, yet water vapor can escape. By keeping building materials dry, a weather-resistivebarrier improves building durability, decreasesmaintenance costs, and reduces the risk ofmoisture-related problems such as bugs, mold,mildew, and rot. Some weather-resistive barriers also reduce air infiltration, cutting utilitycosts and increasing comfort.TYPES AND COSTS OF WEATHERRESISTIVE BARRIERSBuilding paper is a traditional paper sheet or feltmaterial that is asphalt coated or impregnated toincrease its strength and resistance to waterpenetration. It is primarily employed to protectagainst moisture as a drainage layer. Housewraprefers to spun-plastic sheet materials that arewrapped around a house to protect againstmoisture penetration. If properly sealed, housewrap can also serve as an air retarder to reduceinfiltration. In some wall systems, sealed waterresistive sheathing such as rigid foam board canserve as the weather-resistive barrier, eliminatingany need for building paper or housewrap.Building paper typically costs about $300, materialand labor, to cover a 2,500-square-foot home. Itusually comes in a 3-foot roll that one person caninstall. Housewrap costs about $450, materialsand labor, for the same size house. While it isavailable in 3-foot rolls, rolls are usually 9-feet wideand require two people for installation.

FURRED-OUT SIDING

1⁄2" Gap behind siding

Weather-resistive barrier

Sheathing

Siding

1⁄2" x 2" Strips

Studs and insulation

arriers make an effective air

eams and penetrations are

 appropriate sealant or tape.

 building paper is not a true

ousewrap air leakage rates

ury pressure differential) fall

0.08 CFM/ft2—the higher the

 airflow.

arriers vary in their resis

traviolet (UV) radiation, and

This is important in resisting

ion or under wind loading.

ghly resistant to tearing,

er.

V rays within sunlight will

g materials during the

ation process. Most building

istant, whereas recom

 exposure limits vary widely

nufacturer).

e—Housewrap tolerates

ecause plastic does not

uilding paper absorbs mois

elp dry out water otherwise

10/29/00, 9:50 AM