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Community and Q&A

Windows – Canned spray foam vs. ExoAir foam tape

jackofalltrades777 | Posted in Green Products and Materials on

I noticed that builders will use canned spray foam to fill in the gaps between the window and the window bucks. The spray foam is messy and needs to be trimmed back on the interior and exterior since trim work cannot be done properly. I also question spray foams ability to expand and contract as window frames do over the course of the life of the home. I also have seen smoke pencil tests done after spray foam and there are noticeable air gaps between the window frame and buck.

There is a foam tape product made by Tremco called EXO AIR and it basically is installed underneath the window frame and window buck and the foam expands to close in the gaps. It stays flexible for the life of the window and is much cleaner and easier to trim a window once installed.

So why do window installers rely on canned spray foam so much when they are not airtight and messy to deal with?

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  1. GBA Editor
    Martin Holladay | | #1

    I reviewed Tremco ExoAir foam tape back in June 2013. Here is a link to my review: New Green Building Products.

    The product has a few disadvantages. But if you like it, you should continue to use it. I don't doubt that, if properly used, it provides a better air seal than canned spray foam.

    Another option is a European tape designed for air-sealing windows -- for example, Tescon Profil tape.

  2. wjrobinson | | #2

    I believe I get a good seal with spray foam. What I started doing years ago was to rewrite my window ROs list increasing the width and height. I also do not fill the space with foam, I foam the deep back, check it, then fill the rest with fiberglass.

    The RO that the manufacture lists has never been wide enough to use spray foam. Good for gaskets maybe though as Peter uses. Never tried gaskets,

    Also if one is to install a slanted sill rough opening, one needs a larger RO than factory list. By the way Martin, if you look at many factory windows, the factories are not building their windows to be installed on slanted rough opening sills.

    So much of what we talk about doing right here at GBA is not standard in our industry. We are like 1% of the market?

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