PERM-A-BARRIER® Detail Membrane

Self-adhesive, rubberized asphalt/polyethylene detail membrane for air and vapour barrier applications

Product Description

PERM-A-BARRIER® Detail Membrane is ideal for protecting and sealing critical areas of the building superstructure from damaging effects of the elements. By minimizing air and water vapour flow through the building exterior at transition areas, PERM-A-BARRIER® Detail Membrane:

  • Seals transition and detail areas to provide a continuous air barrier
  • Prevents premature deterioration of the building envelope.


Surface Preparation

Surface must be smooth, clean, dry and free of voids, spalled areas, loose aggregate, loose nails, sharp protrusions or other matter that will hinder the adhesion or regularity of the wall membrane installation. Clean loose dust or dirt from the surface to which the detail membrane is to be applied by wiping with a clean, dry cloth or brush.


PERM-A-BARRIER® Detail Membrane may only be applied in dry weather when air and surface temperatures are above -5°C.


Surfaces should be primed with one coat of GCP’s solvent based primer - BITUTHENE® Primer S2. It is used to allow priming and installation of membrane on damp surfaces or “green” concrete. BITUTHENE® Primer S2 can be applied by brush or roller.

DO NOT apply any primer to PERM-A-BARRIER® Detail Membrane.

The drive for continual improvements in performance may result in product modifications. Your GCP representative will be able to provide up-to-date advice.

Detail Membrane Application

Pre-cut PERM-A-BARRIER® Detail Membrane to easily handled lengths. Peel release paper from roll to expose rubberised asphalt and carefully position tape against substrate. Press firmly into place with a steel hand roller or the back of a utility knife as soon as possible, fully adhering the tape to the substrate to prevent water from migrating under the PERM-A-BARRIER® Detail Membrane. Overlap adjacent pieces 50 mm and roll overlap with a steel hand roller.

When applying Detail Membrane to Perm A Barrier VC20

Apply a bead of BITUTHENE® Mastic along all top edges, cuts, penetrations and trowel into place.

No reglet is necessary when installing PERM-A-BARRIER® Detail Membrane to vertical surfaces. Complete installation instructions and details are available upon request.

Details shown are typical illustrations only and not working drawings. For assistance with working drawings and additional technical advice please contact GCP Technical Services.

If wrinkles develop, carefully cut out affected area and replace in similar procedure outlined in the Application section. The repair piece must be pressed into place with a hand roller as soon as possible to ensure continuous and intimate contact with the substrate.

Membrane Protection

PERM-A-BARRIER® Detail Membrane must be protected from damage by other trades or construction materials.


PERM-A-BARRIER® membrane systems must not be applied in areas where they will be permanently exposed to UV light and must be covered within a reasonable amount of time, not to exceed 30 days.

Product Advantages

  • Fully bonded - transmits wind loads directly to the substrate
  • Waterproof and impermeable to moisture - impermeable to the passage of liquid water and water vapour
  • Cross laminated film - provides dimensional stability, high tear strength, puncture and impact resistance
  • Cold applied - no flame hazard; self-adhesive overlaps ensure continuity
  • Flexible - accommodates minor settlement and shrinkage movement
  • Controlled thickness - factory made sheet ensures constant, non-variable site application
  • Aggressive, conformable adhesive - allows self-sealing around mechanical fasteners
  • Wide application window - PERM-A-BARRIER® Detail Membrane surface and ambient temperatures at -5°C and above

Physical Properties

Property Typical Value Test Method
Thickness 1 mm ASTM D3767 method A
Minimum tensile strength, membranes 2.8 MPa ASTM D412 die C modified
Minimum tensile strength, film 34.5 MPa ASTM D412 die C modified
Minimum elongation, to failure of rubberized asphalt 200 % ASTM D412 die C modified
Pliability, at 180° bend over 25mm mandrel Pass at -32ºC ASTM D1970
Crack Cycling, 3.2 mm at -32ºC Unaffected ASTM C836
Minimum puncture resistance, membrane 178 N ASTM E154
Lap peel adhesion at minimum application temperature 700 N/m width ASTM D1876 modified
Maximum permeance to water vapour transmission 2.9 ng/Pa.s.m2 ASTM E96 method B
Air permeance¹ <0.001 l/s/m2 ASTM E2178
Air permeance of in-place membrane² No change in air permance value ASTM E330
Water absorption (weight gain at 24 hours) 0.1 % ASTM 570


  1. Air permeance measured at a pressure differential of 68 Pa Hg.
  2. Air permeance measured at a pressure differential of 68 Pa Hg after wall being subjected to a negative 3014 Pa Hg pressure difference for 10 seconds.

All declared values shown in this data sheet are based on test results determined under laboratory conditions and with the product sample taken directly from stock in its original packing without any alteration or modification of its component parts.

Storage and Handling Information

All materials must be protected from rain and physical damage. Pallets of PERM-A-BARRIER® Detail Membrane must not be double stacked on the job site. Provide cover on top and all sides, allowing for adequate ventilation. Store membrane where temperatures will not exceed 30°C for extended periods.


PERM-A-BARRIER® Detail Membrane
Widths Rolls per carton Approx. Weight per roll
100 mm x 22.9 m 9 rolls 3.2 kg
150 mm x 22.9 m 6 rolls 4.7 kg
225 mm x 22.9 m 3 rolls 9.7 kg
300 mm x 22.9 m    
Ancillary Products: BITUTHENE® Primer S2
Coverage 5 & 20 litre can 10-12 sq m per litre (depending upon method of application, surface porosity and ambient temperature)
BITUTHENE® Mastic 4.5 litre can

Health and Safety

There is no legal requirement for a Safety Data Sheet for PERM-A-BARRIER® membranes and flashing. Refer to product carton for additional safety information. For health and safety questions please contact GCP Applied Technologies Limited.

For BITUTHENE® Primer S2 and BITUTHENE® Mastic, read the product label and Safety Data Sheet (SDS) before use. Users must comply with all risk and safety phrases. SDS’s can be obtained from GCP Applied Technologies. | Australia customer service: 1800 855 525

We hope the information here will be helpful. It is based on data and knowledge considered to be true and accurate, and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. Please read all statements, recommendations, and suggestions in conjunction with our conditions of sale, which apply to all goods supplied by us. No statement, recommendation, or suggestion is intended for any use that would infringe any patent, copyright, or other third party right.

Perm-A-Barrier is a trademark, which may be registered in the United States and/or other countries, of GCP Applied Technologies Inc. This trademark list has been compiled using available published information as of the publication date and may not accurately reflect current trademark ownership or status.

© Copyright 2017 GCP Applied Technologies Inc. All rights reserved.

GCP Applied Technologies Inc., 2325 Lakeview Parkway, Alpharetta, GA 30009, USA
GCP Australia Pty. Ltd., 14 Colebard Street West, Archerfield, Brisbane, Queensland 4108, Australia
This document is only current as of the last updated date stated below and is valid only for use in Australia. 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 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: 2022-01-31