Spray applied air and vapour barrier

Product Description

PERM-A-BARRIER® Liquid is a two component, synthetic rubber, cold-vulcanized, fluid applied membrane. It cures to form a resilient, monolithic, fully bonded elastomeric sheet. 

PERM-A-BARRIER® Liquid will protect above grade wall assemblies against the damaging effects of air, vapor and water ingress. PERM-A-BARRIER® Liquid also provides an effective barrier against air infiltration and exfiltration and associated energy loss and condensation problems.

The Volatile Organic Compound (VOC) content of PERM-A-BARRIER® Liquid is less than 75 g/L.

Architectural and industrial maintenance regulations limit the VOC content in products classified as architectural coatings. Refer to Technical Letters at for most current list of allowable limits.

Product Advantages

  • Air tight - Meets ASTM E2357 standard as required by IECC 2012
  • Fully bonded - transmits wind loads directly to the substrate
  • Elastomeric - accommodates minor structural movements and will bridge cracks
  • Asphalt free formulation - does not become brittle with age and remains flexible to -23°F (-30°C)
  • Chemical cure - no loss of volume; wet thickness is equal to dry thickness
  • Seamless - continuous membrane integrity with no laps
  • Primerless - applied directly to the substrate with minimal surface preparation
  • Damp surface tolerant - can be applied to damp-totouch surfaces
  • Solvent free
  • Cold applied - eliminates fire hazards during application
  • Quick and easy application - by airless spray
  • Wide application window - can be sprayed down to 20°F (-7°C)
  • Versatile - easy to use at details such as internal and external corners, brick ties, penetrations, etc.
  • Enhanced weatherability - product can be exposed to UV up to a maximum of 60 days

Principal Applications

New and remedial air and vapour barriers for commercial and residential applications:

  • Concrete block walls with brick veneer or pre-formed cladding panels
  • Steel or wood stud walls with exterior gypsum board, brick veneer or pre-formed panels

Do not specify PERM-A-BARRIER® Liquid for interior applications.

System Components

  • PERM-A-BARRIER® Liquid - or horizontal and vertical applications
  • S100 Sealant - one part neutral curing, ultra low modulus silicone sealant for detailing and joint treatments
  • BITUTHENE® Liquid Membrane - for details and terminations
  • PERM-A-BARRIER® Wall Flashing - heavy duty fullyadhered membrane for through-wall flashing details
  • PERM-A-BARRIER® Detail Membrane - flexible fully-adhered membrane for flashing around window jambs, door jambs and sills.
  • PERM-A-BARRIER® Aluminum Flashing - Aluminum Faced fully adhered flashing for protecting and sealing critical detail areas



Refer to product label and Safety Data Sheet before use. All users should acquaint themselves with this information prior to working with the material. Carefully read detailed precaution statements on the product labels and SDS before use. SDSs can be obtained from our web site at or by calling our freephone: 866-333-3SBM (3726)


PERM-A-BARRIER® Liquid is installed by airless spray application. GCP has a network of Specialist Spray Applicators who are trained and experienced in spray application. Contact GCP for further details of local applicators, application techniques and spray equipment.

Surface Preparation

All surfaces must be sound and free from spalled areas, loose aggregate, loose nails or screws, sharp protrusions or other matter that will hinder the adhesion or regularity of the membrane installation. The surface should also be free from frost, dirt, grease, oil or other contaminants. Clean loose dust and dirt from the surface by brushing or wiping with a clean, dry cloth.

Concrete and other Monolithic Cementitious Surfaces

Surface irregularities and voids greater than 1/2 in. (13 mm) in depth should be pre-treated with BITUTHENE® Liquid Membrane or repaired with a lean mortar mix or non-shrinking grout. Remove high spots greater than 1/8 in. (3 mm) in height. On highly dusty or porous substrates it may be necessary to apply PROCOR® Concrete Sealer before applying the PERM-A-BARRIER® Liquid.

PERM-A-BARRIER® Liquid may be applied to green (minimum 3 day cure time) concrete or over damp-to-touch surfaces. Remove any visible water prior to application. In green concrete or damp substrate applications, direct sunlight may cause the surface temperature to rise rapidly, drawing moisture from the substrate and resulting in blisters and pinholes in the membrane. Under these conditions it may be necessary to apply PROCOR® Concrete Sealer or a scratch coat of Perm-A-Barrier Liquid before applying the full thickness of the PERM-A-BARRIER® Liquid.

Concrete Masonry Units (CMU)

The CMU surface should be smooth and free from projections. Strike all mortar joints full and flush to the face of the concrete block. Fill all voids and holes, particularly at the mortar joints, with a lean mortar mix or non-shrinking grout. Alternatively, a parge coat (typically one part cement to three parts sand) may be used over the entire surface.

Exterior Sheathing Panels

PERM-A-BARRIER® Liquid may be applied directly to exterior sheathing panels such as exterior drywall, plywood and oriented strand board (OSB) and glass faced wall boards. To avoid deflection at the panel joints, fasten corners and edges with appropriate screws. Fasteners should be driven flush with the panel surface (not counter sunk) and into the framing system in accordance with the manufacturers recommendations. Completely fill the sheathing joint with S100 Sealant and then install a scratch coat (approx. 15-30 mils) of S100 Sealant with a margin trowel or similar onto the face of the sheathing approximately 1 in. (25 mm) on each side of the sheathing joint, ensuring the edges are tapered to prevent shadowing of the spray application. Once the sealant is tack free, the Perm-A-Barrier Liquid may be applied.

For further information on joint treatment refer to Technical Letter 2, Substrate Preparation for Application of PERM-A-BARRIER® Products to Glass-Mat Faced Gypsum Sheathing or Technical Letter 6, Substrate Preparation for PERM-A-BARRIER® Liquid Applications.

Application Temperature

Spray Application

In spray applications using PERM-A-BARRIER® Liquid, it is possible to work at temperatures below 40°F (4°C) provided there is no frost or condensation on the substrate. The minimum temperature for spray application is 20°F (-7°C). Contact your GCP representative for details of cold weather spraying or refer to Technical Letter 9, Spraying Perm-A-Barrier Liquid at low temperatures.


Detailing should be completed prior to applying the full coverage of PERM-A-BARRIER® Liquid. The continuous field application should completely cover the detail areas to provide double thickness coverage. For a complete description and instructions on individual details, consult the separate detail sheets found on our web site at

Transitions to beams, columns, window and door frames, etc. should be made with a strip of PERM-A-BARRIER® Detail Membrane, PERM-A-BARRIER® Aluminum Flashing or PERM-A-BARRIER® Wall Flashing. Only PERM-A-BARRIER® Wall Flashing can be used for through wall flashing applications or under masonry units. Optimum adhesion will be achieved when the self-adhered flashing is lapped onto the cured Perm-A-Barrier Liquid. As soon as the PERM-A-BARRIER® Liquid is tack-free, it is ready to accept the membrane. For further information, refer to Technical Letter 11, Adhesion of Rubberized Asphalt Membranes to PERM-A-BARRIER® Liquid in Air and Vapor Barrier Applications.

A minimum 6 in. (150 mm) wide strip of PERM-A-BARRIER® Detail Membrane, PERM-A-BARRIER® Aluminum Flashing or PERM-A-BARRIER® Wall Flashing should be installed and centered over all outside corners ensuring that all horizontal laps shed water. Self-adhered flashing at corners may be installed prior to the PERM-A-BARRIER® Liquid application in accordance with the applicable data sheet and installation instructions or after PERM-A-BARRIER® Liquid has cured. Avoid installing S100 Sealant under self-adhered flashing.

Any gaps around penetrations should be caulked with BITUTHENE® Liquid Membrane or a polyurethane sealant prior to the PERM-A-BARRIER® Liquid application. Refer to GCP standard penetration detail for PERM-A-BARRIER® Liquid.

Thickness Control

Application thickness is controlled in both horizontal and vertical applications by marking the area and spot checking the thickness with a wet film thickness gauge. Swipe marks on the surface of the PERM-A-BARRIER® Liquid are acceptable as long as the minimum thickness is maintained.


CAUTION! Do not add water or any other material to thin the product.

Part A reacts with water, releasing heat. Do not allow Part A to come in contact with water.

For PERM-A-BARRIER® Liquid, use qualified spray equipment systems. Mixing occurs within the spray gun assembly. Premix Part A prior to pumping to bring any settled material back into solution.

Coverage Rates

PERM-A-BARRIER® Liquid is typically applied at a minimum thickness of 60 mils (1.5 mm). The theoretical coverage rate (not including waste) at a 60 mils (1.5 mm) thickness is about 25 ft2/gal (0.6 m2/L). Coverage rates will be reduced over rough and uneven substrates.

Application of Insulation and Finishes

Perm-A-Barrier Liquid is not suitable for permanent exposure and should be protected from the effects of sunlight as soon as possible after application. Insulation boards may be bonded to the PERM-A-BARRIER® Liquid by pressing them into place after the PERM-A-BARRIER® Liquid has set enough to hold their weight but is still tacky (generally between 30 minutes and 4 hours depending on temperature). PERM-A-BARRIER® Liquid has sufficient tack to hold the weight of the boards but insulation clips are recommended for long term attachment. If the insulation cannot be applied within 60 days of the PERM-A-BARRIER® Liquid application, some form of temporary protection (such as dark plastic sheet or tarpaulins) should be used to protect the product from the effects of sunlight.


Tools and equipment are most effectively cleaned by allowing the material to cure and simply peeling it off the next day. PROCOR® Flushing Oil is available to clean spray equipment.

Storage and Handling Information

PERM-A-BARRIER® Liquid (Part A and Part B) should be stored under cover in original sealed containers above 40°F (4°C) and below 100°F (38°C). Keep Part B from freezing during storage. The shelf life is 9 months in unopened containers.


PERM-A-BARRIER® Liquid should not be used in areas where it will be permanently exposed to sunlight, weather or traffic.

Maximum exposure period is 60 days.

Do not apply PERM-A-BARRIER® Liquid in wet weather. Once applied, the membranes will not be affected by light rain showers.

PERM-A-BARRIER® Liquid should not be used in negative-side waterproofing applications in hydrostatic condition.

PERM-A-BARRIER® Liquid is not compatible with petroleum solvents, fuels and oils, materials containing creosote, pentachlorophenol or linseed oil.


Product Unit of Sale Approximate Coverage1 Weight at 1.5 mm (60 mil) Palletisation
PERM-A-BARRIER® Liquid 75 gallon kit (284 L) 1875 ft2/kit 748 lbs/kit (339 kg), net (573 lbs (260 kg) Part A & 175 lbs (79 kg) Part B) 1 or 2 kits/pallet, for orders of 1 or 2 kits only
BITUTHENE® Liquid Membrane

1.5 gallon (5.7 L) (Part A & Part B)

  18 lbs/kit (8 kg) 100 kits/pallet
BITUTHENE® Liquid Membrane 4 gallon (15 L) (Part A & Part B)   44 lbs/kit (20 kg) 24 kits/pallet
PERM-A-BARRIER® Wall Flashing
12 in. (305 mm)
3 rolls 75 linear ft per roll (7 m) 25 lbs/roll (11 kg) 25 cartons (75 rolls) per pallet
PERM-A-BARRIER® Wall Flashing
18 in. (457 mm)
2 rolls 75 linear ft per roll (7 m) 37.5 lbs/roll (17 kg) 25 cartons (50 rolls) per pallet
PERM-A-BARRIER® Wall Flashing
24 in. (610 mm)
1 roll 75 linear ft per roll (7 m) 55 lbs/roll (25 kg) 35 cartons (35 rolls) per pallet
PERM-A-BARRIER® Wall Flashing
36 in. (914 mm)
1 roll 75 linear ft per roll (7 m) 75 lbs/roll (34 kg) 25 cartons (25 rolls) per pallet
PERM-A-BARRIER® Detail Membrane
6 in. (152 mm)
6 rolls
75 linear ft per roll (7 m) 11 lbs/roll (5 kg) 25 cartons (150 rolls) per pallet
PERM-A-BARRIER® Detail Membrane
9 in. (225 mm)
4 rolls 75 linear ft per roll (7 m) 16 lbs/roll (7 kg) 25 cartons (100 rolls) per pallet
PERM-A-BARRIER® Detail Membrane
12 in. (305 mm)
3 rolls 75 linear ft per roll (7 m) 22 lbs/roll (10 kg) 35 cartons (75 rolls) per pallet

Physical Properties

Property Typical Value Test Method
Air permeance at 1.57 psf (75 Pa) pressure difference <0.0002 cfm/ft2 (<0.001 L/s/m2) ASTM E2178
Assembly air permeance at 1.57 psf (75 Pa) pressure difference1 <0.0008 cfm/ft2 (<0.004 L/s/m2) ASTM E2357
Water vapour permeance 0.08 Perms (4.6 ng/Pa.s.m2) ASTM E96 - method B
Water vapour permeance after aging2 0.033 Perms (1.9 ng/Pa.s.m2) CAN/CGSB-51.33-89
Pull adhesion to concrete block (CMU)4 35 psi (0.24 N/mm2) ASTM D4541
Pull adhesion to glass faced wall board 18 psi (0.12 N/mm2) (pulls board apart) ASTM D4541
Peel adhesion to concrete4 5 lbs/in. (880 N/m) ASTM D903 modified3
Elongation 500% ASTM D412
Pliability, 180° bend over 1 in. (25 mm)
mandrel at -23°F (-30°C)
Unaffected ASTM D1970
Low temperature flexibility and crack bridging
1/8 in. (3.2 mm) crack cycling at -15°F (-26°C)
Pass ASTM C836
Extensibility over 1/4 in. (6.4 mm) crack after heat aging Pass ASTM C836
Colour Green  
Solids content 100% ASTM D1644

Results below detectable limits of laboratory equipment.
Aged for 25 cycles of 3 hours at 122°F (50°C), 3 hours in water at 70°F (21°C), 18 hours at 14°F (-10°C)
PERM-A-BARRIER® Liquid is applied to concrete and allowed to cure. Peel adhesion of the membrane is measured at a rate of 2 in. (50 mm) per minute with a peel angle of 90°.
Lab results, field results may vary | 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, Bituthene® and Hydroduct® are trademarks, 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. Procor® is a U.S. registered trademark of GCP Applied Technologies Inc, and is used in Canada under license from PROCOR LIMITED. FibaTape is a registered trademark of Bayex Corporation.

© Copyright 2018 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: 2022-06-06