Rigid foam over concrete in garage
dool
| Posted in General Questions on
Im in Albuquerque, NM, zone 4b I believe.
I’m in the process of turning a garage into bedrooms, I want to install rigid foam on the concrete floor and then frame over it to bring the floor level with the rest of the house. Should I place a plastic barrier before the foam, is it needed? Is there a specific tape needed to tape the joints? Should the foam be glued or nailed to the concrete or just float?
Any advice is greatly appreciated, thank you.
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Replies
Hi Adam,
I don't have any advice...except that you may find some "Insight" in this article
http://www.buildingscience.com/documents/insights/bsi-059-slab-happy/files/BSI-059_Slab_Happy.pdf
More than likely, in ABQ, your garage slab does not have a capillary break or a moisture barrier underneath; therefore, you should seal all cracks in the concrete floor and cover it with a sealer. On top of the sealer, I would install continuous 2” taped rigid foam (The tape is recommended by the foam manufacturer), then one or two layers of treated plywood, depending on the finish floor material (1st layer of plywood must be nailed to the concrete). If you have a dropped and sloped garage, you could level it with a layer of concrete on top of the foam, and then you can finish it like a regular slab floor.
Adam,
I've seen several articles about insulating a floor over concrete in Fine Homebuilding. There is a more recent article but I can't find the reference yet.
http://www.finehomebuilding.com/how-to/articles/wood-floor-survive-anywhere.aspx?ac=fp
http://www.finehomebuilding.com/how-to/qa/finishing-a-basement-floor.aspx
Hope this helps. Lucy
Thanks for the advice, will read the linked articles now.
I found another article in the QA section of the Journal of Light Construction.
Q&A: Insulated Wood Floor Over Concrete - http://www.jlconline.com/flooring/q-a--insulated-wood-floor-over-concrete.aspx (1994)
This installer says that he lets it float and suggested a plastic barrier under the foam that was taped. The installer in the Fine Homebuilding article says that he also prefers a floating floor. He did not insulate the floor with foam though that just seems like an extra step.
I've never installed a floor, just read these articles to see if that would be useful in my basement so I am not speaking from experience.
Lucy