New Green Building Products

Every energy-efficient home needs a tight air barrier. Here are some products that might help: a cover for recessed cans, a caulk for polyethylene, and a handful of new housewraps

Posted on Sep 10 by Martin Holladay, GBA Advisor

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A cover for recessed can lights. The manufacturer of the Tenmat cover for recessed can lights has chosen to illustrate the product with one of the worst fiberglass-batt insulating jobs ever photographed. The Tenmat cover has been cut vertically to illustrate how it fits over the light fixture.

In this new-product roundup, I'll look at a cover for recessed can lights, a new caulk for polyethylene, and several new water-resistive barriers (WRBs) that promise better performance than Tyvek or Typar.

A fire-resistant hat for recessed can lights
A Delaware manufacturer named Tenmat is selling an airtight hat for recessed can lights. Tenmat light covers are made from mineral wool; according to the manufacturer, they are fire-resistant.

Tenmat covers are installed from the attic. After making a slit in the cover to accommodate the electrical cable, the cover is pushed down to the drywall ceiling. The cover should be glued to the drywall with canned foam or thermal caulk. Needless to say, the slit or hole made for the cable needs to be sealed with housewrap tape or canned foam.

Once the Tenmat covers are installed, the ceiling can be insulated with almost any type of insulation, including fiberglass batts, cellulose, or spray polyurethane foam.

Tenmat covers come in two sizes: "regular" (9 inches high and 14 inches wide) and "oversized" (10 3/4 inches high and 16 inches wide). Energy Federation Incorporated sells regular size Tenmat covers for $19.65 each.

Besides the high price, there's only one catch to Tenmat covers: the covers can only be used for recessed can fixtures equipped with CFL or LED bulbs. If a homeowner inserts an incandescent or halogen bulb in the fixture, it can overheat.

Dow Corning 758 caulk
Dow Corning has come out with a new caulk that sticks to a great variety of materials, including polyethylene.

FOR MORE INFORMATION

Cosella-Dörken Products
4655 Delta Way
Beamsville, Ontario L0R 1B4
Canada
Tel: 905-563-3255 or 888-433-5824
info@cosella-dorken.com

Dow Corning
P.O. Box 994
Midland, MI 48686-0994
800-248-2481

Henry Co.
909 North Sepulveda Boulevard
El Segundo, CA 90245
800-486-1278

Tenmat
23 Copper Drive
Newport, DE 19804
302-633-6600

VaproShield
915 26th Ave. NW, Suite C5
Gig Harbor, WA 98335
866-731-7663
sales@vaproshield.com

The new sealant, Dow Corning 758, is a silicone caulk that the manufacturer claims will stick to polyethylene, polypropylene, vinyl, polyolefin housewrap (for example, Typar), peel-and-stick flashing (including Vycor and Tyvek window flashing), and peel-and-stick membrane (including Ice and Water Shield). The broad range of materials to which it sticks makes the caulk particularly useful for window installation.

Dow Corning 759 is said to be a low-VOC product.

A warning to anyone seeking technical information from Dow Corning on this product: my repeated attempts to obtain answers to a few basic questions about 758 sealant were ignored by the company. If any GBA readers can provide further information, please post a comment below.

Delta-Fassade S
Did you ever wonder why housewrap manufacturers can't come up with a tougher product — something that doesn't rip away from nail heads or get damaged by ladders?

If you're tired of Tyvek and Typar, and willing to pay for something tougher, you might want to look at four housewraps from Cosella-Dörken Products.

In ascending order of price, Cosella-Dörken's tear-resistant weather-resistive barriers are Vent S, Delta-Foxx, Delta-Maxx, and Fassade S.

Rated at 69 perms, Vent S costs about 45 cents a square foot — roughly three or four times the price of Tyvek or Typar. Delta-Foxx (214 perms) is more permeable than Vent S, but also pricier — between 65 and 90 cents a square foot. In Europe, Delta-Foxx is used on roofs as well as walls.

At 14 perms, Delta-Maxx has a lower permeance than Cosella-Dörken's other WRBs. However, it has the greatest tear resistance.

If you need a WRB that can withstand a certain amount of UV exposure — for example, a WRB for use behind open-joint cladding systems — you can use Cosella-Dörken's top-of-the-line WRB, a product called Fassade S. Delta Fassade S (74 perms) costs between $1.10 and $1.20 a square foot.

Fasssade S has UV inhibitors that allow it to be installed behind unusual cladding systems — for example, a screen made of gapped boards that admit some sunlight. Gaps may be up to 2 inches wide. "Basically it is designed to be exposed to some sunlight throughout its life," said Peter Barrett, product manager.

Although it can withstand quite a bit of UV exposure, the manufacturer recommends that it be covered with cladding within 3 months of installation. Fassade S does not qualify as an air barrier.

To make sure that fastener penetrations are watertight, the manufacturer recommends the use of tape or a foam gasket between the WRB and any girt or strapping attached to the WRB.

Building scientist John Straube tested Fassade S by attaching it to the exterior of a small trailer. After driving the trailer for more than 6,000 miles, through snow and heat, he says that the housewrap "is still going strong.There was not a bit of deterioration or fraying that I could see in the wrap."

WrapShield SA
VaproShield is selling a self-adhered WRB called WrapShield SA. Although it's a peel-and-stick product, it's not a rubberized membrane; it's a vapor-permeable housewrap.

The fact that it is a self-adhered wrap gives it several advantages: since it's self-adhering, fewer fastener penetrations are required to install it; it doesn't flap in the wind or suffer from "wind pumping" problems; and it's very airtight.

In addition to being a WRB, WrapShield SA can be used as part of an air barrier system. According to the manufacturer, it sticks well to plywood, OSB, DensGlass sheathing, and concrete blocks. No primer is necessary.

WrapShield SA seals well around small fasteners, although larger fasteners like #12 or #14 screws might require sealing. WrapShield SA works well with a rainscreen application; the manufacturer also makes a vinyl batten called VaproBatten to complete the installation.

WrapShield SA is rated at 50 perms and costs between 82 and 95 cents per square foot.

Henry Blueskin VP
Henry Company, a manufacturer with plants in Ontario and El Segundo, Calif., also manufactures a self-adhered WRB, similar in many ways to WrapShield SA. Henry Company's product is called Blueskin VP.

Blueskin VP has a permeance of 29 perms. It needs to be applied at temperatures of 40°F or warmer. Like WrapShield SA, Blueskin VP has a peel-away paper backing; it can be adhered to a wide variety of substrates (including OSB, plywood, DensGlass, and concrete blocks) without fasteners. A primer must first be installed if the product is used over concrete or concrete blocks.

Last week's blog: "Using Rigid Foam As a Water-Resistive Barrier."