TL-0019 — Exposure Guidelines for PERM-A-BARRIER® Self-Adhered Membranes Technical Letter

PERM-A-BARRIER® self-adhered membranes (including PERM-A-BARRIER® Wall Membrane, PERM-A-BARRIER® Aluminum Wall Membrane, PERM-A-BARRIER® Wall Flashing, PERM-A-BARRIER® Detail Membrane, PERM-A-BARRIER® Aluminum Flashing, PERM-A-BARRIER® NPS and PERM-A-BARRIER® VPS) are not meant to be left permanently exposed to the sun. In general, the membrane should be covered with the final wall covering as soon as possible. However, GCP Applied Technologies (GCP) PERM-A-BARRIER® self-adhered membranes may be left exposed (as described in the general exposure guidelines below) if necessary, to accommodate construction scheduling or weather problems.

PERM-A-BARRIER® Self-Adhered Membranes Maximum Exposure Guidelines
Wall Membrane 60 Days
Aluminum Wall Membrane 1 Year
Wall Flashing 60 Days
Detail Membrane 60 Days
Aluminum Flashing 1 Year
NPS 1 Year
VPS 150 Days

During the time period the product is left exposed there are two primary factors at work on the membrane: heat and ultraviolet (UV) radiation. Heat will not likely affect the performance but there may be some changes in appearance depending on the climate and length of exposure. UV radiation will not affect the membrane in any significant way during its maximum exposure limit.

After the maximum exposure period, it is normal for the self-adhered membranes to appear slightly wrinkled. There may be a small amount of curling at the edges of the membrane as well. None of these issues will affect the performance of GCP self-adhered underlayments once covered.

Before covering the membrane after a long exposure, it should be inspected to ensure that any wrinkling or other movement that has taken place has not affected any of the lap areas. If a wrinkle forms that extends to the edge of a lap, it must be cut, pressed down, and patched before the wall is covered. Any curling at the edges or corners must be cut and patched if the affected area is more than 1/2 inch (13 mm) wide.

Use a patch of membrane extending past the damaged area 6 inches (150 mm) in all directions and seal any non-watershedding edges with BITUTHENE® Liquid Membrane or BITUTHENE® Mastic. Note: When installing PERM-A-BARRIER® self-adhered membranes against PERM-A-BARRIER® Liquid or PERM-A-BARRIER® VPL or VPL LT, BITUTHENE® Liquid Membrane should be used in lieu of BITUTHENE® Mastic.

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This document is only current as of the last updated date stated below and is valid only for use in the United States. It is important that you always refer to the currently available information at the URL below to provide the most current product information at the time of use. Additional literature such as Contractor Manuals, Technical Bulletins, Detail Drawings and detailing recommendations and other relevant documents are also available on www.gcpat.com. Information found on other websites must not be relied upon, as they may not be up-to-date or applicable to the conditions in your location and we do not accept any responsibility for their content. If there are any conflicts or if you need more information, please contact GCP Customer Service.

Last Updated: 2018-11-29

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