Thursday, September 17, 2020

Installing Vapor Barriers and Vapor Retarders


What are Vapor Barriers?

Vapor barrier in basement/crawlspace

Vapor barriers and vapor retarders provide additional layers of protection in basements and crawlspaces, under foundations and concrete slab. They are important in saving time and money through the mitigation of moisture and air by reducing mold, musty odor, and water penetration. Examples of vapor barriers and vapor retarders include film, non-woven fabrics, and metalized or foil covered laminates. Each provides different properties including surface protection, reflective properties and vapor permeance (water vapor transmission).  

Installation with Vapor Barrier Tapes

To provide effective installation of vapor barriers and vapor retarders, pressure-sensitive vapor barrier tapes are important in sealing, repairing and seaming the vapor barriers or retarders during application. They are used to seal overlapped seams during installation, attach vapor barriers to the top of the footings and against the wall, repair damaged vapor barriers and installation cuts, and seal protrusions such as pipes, duct work, rebar or wire bundles.
Vapor barrier seaming in concrete underlayment application

Vapor barrier tapes used include those tapes providing low permeance, which include: polyethylene tapes of varying thickness providing conformability, polypropylene tapes with aggressive, low permeance adhesive systems, and aluminum foil tapes providing basically zero water vapor transmission.   

Compliance to specifications is essential to the effective installation of vapor barrier and vapor retarder systems. Some standards include ASTM E1643, ASTM 1745 and IRC 408. 

(IPG manufactures vapor barriers and vapor retarders. To learn more, please contact

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