Attaching rigid foam… with tape?
To attach rigid foam to a concrete wall, most people seem to prefer screws, plastic anchors, or adhesive. Is it possible to simply use tape instead? It could be rolled up into loops to form a double-sided tape loop that has some allowance for irregularities in the concrete (these would go on the back of the foam), and perhaps the side edge could also be taped to the wall with a folded “L” piece of tape, before the next piece of rigid foam is put up.
No drilling, no mess, no application of pressure needed while waiting for adhesive to dry. Seems like it could work great. But no one seems to do it. Is that because it’s incredibly ingenious, or just stupid?
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Replies
Nick,
No one really knows how long the adhesives in today's tapes will last. I think most builders would react to your suggestion this way: "That doesn't feel very secure to me."
Someone has to be the guinea pig, or we'll never know. Feel free to experiment. If you do, I suggest that you choose a high-quality tape (one of the European tapes sold by Small Planet Workshop or 475).
Back in the mid-80s, I used adhesive to attach XPS to the interior side of the concrete walls of a crawl space, and wondered whether the method would work. Thirty years later, the rigid foam is still firmly in place. You never know till you try.
Nick, I'd be inclined to use the tape as a temporary fix while the adhesive dried rather than relying on it over the life of the house.
Mounting foam with adhesives don't cut it from a fire safety point of view, unless it's fire-rated polyiso, in which case it doesn't matter if the foam comes off when heated. The code-required thermal barrier needs to be mechanically secured with fasteners to something more structural than foam too.
I don't know of any tapes designed to work over the long-term on concrete, which will see wide seasonal swings in temperature & moisture content.
Dana, We seem to be getting a lot of questions that are dependant on where the OP lives for which codes apply. I wish people would specify so they can get appropriate answers.
Local climate (both weather & legal/code) does indeed make a difference for a lot of issues! When in doubt, refer to the IRC but know that there will be exceptions and outright contraction with local code sometimes.
Dana, I was more intimating that there is a chance they may live up here in Canada... Your poor cousins to the north.