Membrain™ – The Smart Vapor Retarder
During the heating season, when relative humidities are typically low, MemBrain works as a vapor retarder.
Moisture is the bane of every builder and a hidden risk in every building. Lurking in the wall cavity, moisture creates ideal conditions for mold, mildew, rot and the respiratory health problems they can cause. Especially in regions with extreme seasonal fluctuations in climate and humidity, there’s no foolproof way to keep moisture from getting into a wall. But now there’s a revolutionary way to help get it out.
MEMBRAIN PROTECTS… AND BREATHES.
MemBrain was designed on an ingenious principle: If you can’t escape the possibility of moisture entering a wall, why not let the moisture in the wall escape? Made from an advanced material that changes its permeability with the ambient humidity condition, MemBrain acts like a traditional vapor retarder to protect wall cavities, but also allows closed building envelope systems to dramatically increase their drying potential with seasonal climatic changes.
HOW DOES IT KNOW?
Designed to be applied over unfaced fiber glass insulation, loose-fill applications and spray foam, MemBrain looks similar to typical polyethylene sheeting, but is actually a polyamide-based material that gives MemBrain its unique ability to adapt its permeability depending on the climatic conditions. With a high resistance to water vapor in winter or low humidity, MemBrain behaves like a moisture vapor retarder such as poly sheeting. When the relative humidity increases, as in the summer season, its water vapor permeability increases dramatically. This allows water vapor to escape the wall cavity easily.
WHAT’S THE BIG DIFFERENCE?
In summer conditions, exterior areas can often be warmer than the interior, creating a reverse vapor drive into the interior. Unlike the polyethylene sheeting currently favored in many areas, MemBrain can vary its water vapor permeability in humid conditions, to allow some moisture through. This transformation permits drying to occur, in either direction, through the process of vapor diffusion while minimizing moisture penetration during low humidity conditions.
WHERE TO USE IT.
Membrain is recommended only for heating and mixed climates; it is not suitable for cooling climates with high outdoor humidities. Nor is it suitable for areas with very high, constant indoor humidity levels, such as spaces with swimming pools or spas, or buildings where relative humidity levels are maintained above 50%. Short excursions to high humidity (such as in bathrooms) are not a concern, though due to the buffering action of the interior finish.
WHY DIDN’T ANYONE THINK OF THIS BEFORE?
Vapor retarders have been used for decades to protect the wooden parts in a roof or wall from moisture damage by minimizing the diffusion of moisture in areas where it can create problems. But these vapor retarders have a fixed permeability that can’t adapt to changing conditions. The patented MemBrain technology was first introduced in Europe over ten years ago and is steadily becoming the preferred vapor retarder among European specifiers.
HOW SMART IS IT?
Using MemBrain will reduce your risk/liability due to moisture problems. Though it is a high-quality, premium product, MemBrain will only add about $300-$500 to the total of a new home*. So using MemBrain costs just a little more, but is always a smart investment.
* Based on an approximate exterior wall space for an average 2,400 sq. ft. home.
During the cooling season, when relative humidities are typically high. MemBrain changes its permeance to increase drying potential.
MEAN RELATIVE HUMIDITY (%)
With MemBrain’s permeability, moisture can escape from the wall cavity for optimal drying.
MemBrain™, The SMART Vapour Retarder
1. PRODUCT NAME
CertainTeed MemBrain™ Smart Vapour Retarder. Protected by one or more of the following patents:
Can. Pat. No. 2215502;U.S. Pat. Nos. 6,808,772; 6,878,455; 6,890,666; and 7,008,800
Other U.S. and foregin patents pending.
P.O. Box 860 Valley Forge, PA 19482-0105
800-233-8990 Fax: 610-341-7994
3. PRODUCT DESCRIPTION
Basic Use: CertainTeed MemBrain Smart Vapour Retarder is a vapour retarder sheeting intended for use with unfaced, vapour permeable mass insulation (fibre glass and mineral wool) in wall and ceiling cavities.
Benefits: MemBrain Smart Vapour Retarder is a polyamide film that changes its permeability with the ambient humidity condition. The product’s permeance is 1 perm or less when tested in accordance with ASTM E96, dry cup method, and increases to greater than 10 perms using the wet cup method. MemBrain allows closed building envelope systems to increase their drying potential with seasonal climatic changes. With a high resistance to water vapour in winter or low humidity, MemBrain behaves like a moisture vapour barrier such as 6-mil polyethylene sheeting. With an increase in relative humidity, MemBrain’s permeability increases dramatically, permitting drying to occur and decreasing moisture accumulation within the construction and the potential moisture damage.
This product can be used in place of traditional vapour retarders with unfaced fibre glass insulation, loose fill, or spray foam to provide an insulation system that is ideal in some of the more severe climate condition areas in terms of both temperature and humidity.
Composition and Materials: MemBrain Smart Vapour Retarder is formed by blowing a 2-mil thick film of polyamide (Nylon).
Limitations: MemBrain Smart Vapour Retarder is recommended for use in heating and mixed climates. The product is not suited for cooling climates with high outdoor humidities or in buildings with exceptionally high, constant indoor humidity levels, such as swimming pools and spas. This product should also not be used with specialty-conditioned spaces or where residential humidification systems are set at relative humidities greater than 50%. MemBrain’s performance in rooms with short peaks of high humidity, such as bathrooms and kitchens, will not be affected because of the buffering action of interior finishes.
Do not use low permeance interior finishes such as vinyl wallpaper or vapour retarding paints with MemBrain. The drying benefits of MemBrain will diminish with the use of low permeance finishes. MemBrain should not be used as a vapour barrier between concrete sub floors and flooring materials, or as a ground cover in basements and crawlspaces. This product is not recommended for applications having direct or indirect (reflected) ultraviolet light exposure due to solar or electrical sources. Special care should be taken when working with an open flame. Check local practice and/or building codes for use of vapour barriers. To avoid danger of suffocation, keep this and all plastic film away from babies and small children.
Sizes: This product is manufactured in nominal widths to cover interior walls that are 8, 9, 10 and 12 feet high. The material is folded and rolled to create rolls containing 100 linear feet of product. Available standard sizes are listed in Table 1.
4. TECHNICAL DATA
• Model Building Codes:
– National Building code of Canada 2005 Articles 184.108.40.206(1), (2) and (3) Articles 220.127.116.11, 18.104.22.168 and 22.214.171.124 CCMC Report #13278-B
– BOCA, ICBO, SBCCI and ICC
• Material Standards:
– ASTM C665 Section 7.4, Water-Vapour Permeance
– ASTM E96
• Fire Hazard Classification:
– ASTM E84 Surface burning characteristics Max. Flame Spread Index: 20 Max. Smoke Developed Index: 55
• Water Vapour Permeance:
– ≤ 1.0 perm (57ng/Pa•s•m2) (ASTM E96, Desiccant method)
– > 10 perms (570ng/Pa•s•m2) (ASTM E96, Water method)
• Fungi Resistance:
– No growth (ASTM C1338)
– No unusual aspect of corrosion such as pitting, cracking and adhesive cure inhibition (ASTM C665)
Quality Assurance: Many of CertainTeed’s manufacturing plants are registered to ISO 9001-2000 standards.
For most areas, vapour retarders should be installed on the warm-inwinter side of the insulation (toward the interior). MemBrain is not intended to be used as an exterior vapour retarder. Check local practice and/or building codes.
Installation in wood framing:
Same as polyethylene sheeting.
Please see MemBrain Smart Vapour Retarder Installation Instructions For Wood Framing (30-28-083) and MemBrain Smart Vapour Retarder Installation Instructions For Steel Framing (30-28-089).
Installation as an Air Barrier System: MemBrain may be installed as a continuous interior air barrier system. Please see MemBrain Air Barrier Installation for Wood Framing (30-28-137).
6. AVAILABILITY AND COST
For availability and cost, contact your local retailer or distributor, or call CertainTeed at 800-233-8990.
This product is covered by a limited one-year warranty against manufacturer’s defects.
9. TECHNICAL SERVICES
Technical assistance can be obtained from either the local CertainTeed sales representative, or by calling CertainTeed at
10. FILING SYSTEMS
Additional product information is available upon request.