Product Review: World’s Best Sill Seal
T-Shaped cross section provides redundant air seals
Posted on Jan 11 by Martin Holladay, GBA Advisor
A T-shaped cross section blocks air leaks. The rubberized asphalt membrane adhered to the foam provides a tenacious seal to the wall sheathing and the outside face of the concrete foundation.
Sill seal made from closed-cell foam does a pretty good job of stopping air leaks on smooth-topped foundations. When the concrete is rough, however, it’s hard for sill seals to bridge the uneven gap under the mudsill.
To address the problem, Protecto Wrap, a Denver manufacturer of peel-and-stick flexible flashing products, has developed the world’s best sill seal. Called Triple Guard, the sill seal includes a gasket of closed-cell polyethylene foam, just like many competing products. But to address the problem of air leakage through gaps caused by irregular concrete foundations, Triple Guard has thicker than usual foam — 3/8 in. thick instead of the more typical 1/4 in.
The foam layer is bonded to a layer of 20-mil peel-and-stick rubberized asphalt, so that the gasket adheres to the top of the concrete foundation. The sill seal has a T-shaped cross-section, with a 4 3/4-in.-wide peel-and-stick flange at a 90° angle to the foam gasket.
The bottom half of the vertical flange is designed to adhere to the outside face of the concrete foundation. Once the walls are framed, the top half of the flange is adhered to the wall sheathing.
At that point, virtually all air infiltration has been blocked.
Lab results back up claims
At the Oak Ridge National Laboratory, senior research engineer Jan Kosny tested the airtightness of sills sealed with Triple Guard. When sealed with conventional foam sill seal, the gap between the concrete and the mudsill in a 9-ft., 6-in. wall assembly had an equivalent leakage area (ELA) of 3.6 square in. When the gap was sealed with Triple Guard, the ELA dropped to 0.3 sq. in.—a 91.7% reduction in air leakage.
“This product gives almost 100% protection against air leakage, as well as moisture leakage in two directions—horizontal and vertical,” said Kosny. “This is a great product.”
Kosny also spoke highly of Triple Guard’s tenacity. “After we were done with our testing, we had some questions about some of the results, and we wanted to repeat some of the testing,” said Kosny. “We said, ‘Let’s remove the Protecto Wrap from the concrete and test the other sealant.’ But can you believe that three people couldn’t take off a ten-foot-long piece of Protecto Wrap in three hours? It’s a very tough product.”
Triple Guard is sold in 25-ft. rolls in two different sizes. It isn’t cheap; the smaller size, intended for use with 2x4 sill plates, costs about $47 per roll. The larger size (for 2x6 sill plates) has a 5 1/2-in.-wide foam strip and costs about $72 per roll.
For more information, visit the manufacturer's Web site or call the manufacturer at (800) 759-9727.
Image Credits:
- Protecto Wrap
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Jan 11, 2010
5:01 PM EST
5:01 PM EST
Not working for me
by Michael Chandler, GBA Advisor
This looks like one of those things they think up at grad school or something. It will never find a place at my jobsite because it doesn't really matter how good the connection is to the bottom plate and the exterior sheathing, the critical connection is between the house wrap and the concrete.
Joe Lstiburek's "FEMA header wrap detail" from the old Canadian R-2000 program still works for me and is way, way cheaper, easier to install, and can be used with termite shields which this product cannot. With that system we fasten a 12" roll of 6 mil poly between the termite flashing and the bottom of the bolt-drilled mud sill and then cover the termite flashing with sill seal before rolling the mud sill down onto the foundation or slab. After the assembly is up and sheathed we simply caulk the edge of the sill seal to the termite flashing and the foundation and pull the poly up onto the sheathing before taping the house wrap to it. Joe's detail also had a top plate component where you ran a twelve inch roll of poly between the top plate and the upper top plate and pulled it down over the house wrap to seal the top plate to the house wrap at the top of the wall to sheathing juncture. (And we gasketed the top plate to the drywall back then, "the Air-tight Drywall Approach." We don't use drywall gaskets these days because we're spray foaming our conditioned attics.)
I rolled my eyes when I saw this the first time, primarily because we are in a place where termite shields still make sense (though no longer required by code and so mostly abandoned) my typical house uses 200' of mud sill, so this product would cost $576 for 2x6 mud sills assuming my crew didn't accidentally wad it up and ruin it during installation. Not a winner to me,
Jan 12, 2010
5:10 AM EST
5:10 AM EST
Great feedback
by Martin Holladay, GBA Advisor
Michael,
Great feedback — thanks. Every new product needs feedback based on field experience, so all of your comments are valuable.
Jan 14, 2010
6:07 PM EST
6:07 PM EST
sill seal
by jeff medanichAnonymous
Several years ago we built a research house to determine what new products and techniques we could implement on a production basis. We used the Triple Guard sill seal and it worked well, although it was quite expensive. Subsequenly we found that it became difficult to use during cold weather construction and did not adhere well to the concrete. The area of the foundation that accepts the vertical leg needs to be clean, dry, and in cold weather you need to apply a primer to the concrete, also sold by the manufacturer, to better assure a good bond, increasing the linear foot cost of this detail.
You also needed to keep the product warm, another challenge when building in cold weather. Although this particular product did not make it into the production process, the concept did by using flexible flashing at this junture but without the integral connection to the sill seal.
This combined with other air sealing measures including the airtight drywall approach, flanged electrical boxes, and strategic caulk and foam application greatly reduced air infiltration rates and became standard procedure in production houses.
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