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Building Envelope Design

Weather resistive barriers are part of an exterior wall system designed to protect building materials from moisture penetration. Weather resistive barriers allow moisture vapor to escape, ensuring building materials remain dry, increasing building performance and decreasing the risk of moisture-related problems such as mold, mildew, rot and sick building syndrome.

Weather Resistive Barriers

Weather resistive barriers are part of an exterior wall system designed to protect building materials from moisture penetration. There are different types of weather resistive barriers including vapor barriers, vapor retarders, air barriers and air retarders.

Not all air barriers are vapor barriers and not all vapor barriers are air barriers, however, all weather resistant barrier membranes must resist entry of liquid water (rain/snow) into the wall system by providing a drainage plane.

There are three general classes of membranes based on permeability.

CLASS 

 MEMBRANE TYPE VAPOR PERMEANCE
Class 1
Vapor Barriers
1 perm or less
Class II Vapor Retarders/Semi Permeable More than 1 perm and less than 10 perms
Class III Breathable 10 perms or more
WALLSHIELD® Fiber Image Construction Water Vapor Transmission Air Permeability
Weather resistant vapor and air permeable breather membrane
GR_fibers_-_50
 Triple layer spunbond polypropylene 576 grams/m2/24hrs
212 perms		 Not an air barrier, but has been tested as a component in a composite air barrier tested assembly

WRAPSHIELD® Fiber Image Construction Water Vapor Transmission Air Permeability
Weather resistant vapor permeable air barrier membrane
OR_fibers_-_50
 Triple layer spunbond polypropylene 308.9 grams/m2/24hrs
50 perms		 0.0019 cmf/ft2
0.0095 L/s/m2

WRAPSHIELDSA® SELF-ADHERED
 Fiber Image Construction Water Vapor Transmission Air Permeability
Weather resistant vapor permeable self adhering air barrier membrane
ProductComparison_SA_Image
 Triple layer spunbond polypropylene 308.9 grams/m2/24hrs
50 perms		 0.0019 cmf/ft2
0.0095 L/s/m2

WRAPSHIELDHS®
 Fiber Image Construction Water Vapor Transmission Air Permeability
Weather resistant vapor permeable air barrier with added drainage layer
wrapshieldhs-filter
 Triple layer spunbond polypropylene with additional pp matrix 308.9 grams/m2/24hrs
50 perms		 0.0019 cmf/ft2

SLOPESHIELD®
 Fiber Image Construction Water Vapor Transmission Air Permeability
Weather resistant
Vapor permeable
Roof Underlayment
slopeshield-filter
 Triple layer spunbond polypropylene 308.9 grams/m2/24hrs
59 perms		 0.0019 cmf/ft2
0.0095 L/s/m2

SLOPESHIELDSA® SELF-ADHERED
 Fiber Image Construction Water Vapor Transmission Air Permeability
Weather resistant
Vapor permeable, self-adhering
Roof Underlayment
slopeshield-filter
 Triple layer spunbond polypropylene 308.9 grams/m2/24hrs
59 perms		 0.0019 cmf/ft2
0.0095 L/s/m2
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