Do I need to use concrete screws for plywood over an insulated floor?
rerskine
| Posted in GBA Pro Help on
i am following your advice on using XPS on concrete basement floor followed by two layers of 1/2 inch plywood. My concrete floor is 15 yrs old will I have trouble with concrete screws in older concrete? Can I just fasten the second layer to the first layer of plywood or can I use adhesive on the first layer or do I need the concrete screws?
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Replies
"Can I just fasten the second layer to the first layer of plywood "
Yes you can float the subfloor. Stagger the joints and use adhesive + screws.
Concrete screws work in concrete of any vintage. Be sure to vacuum out the drilling debris/dust before installing the screws in a slab to keep the screw from bottoming out on the loose (now compresssed) material.
Depends on the concrete. Old slabs tend to spall or have problems with pull out strength. Sinking that many screws in a slab, old or new, is an awful job. I'd leave well enough alone.