I have a bathroom floor that I want to lay new cork flooring on but here is my situation. the floor is two different heights the lower part is concrete floor the higher is wood. I know that I need to bring up the concrete floor even with my wooden side which is about 1 and 1/2" higher. Can I use plywood as my subfloor on the concrete side and if so what is the best way to attach it to the concrete floor.
You will be better off to use a mortar product to raise the lower concrete section. Layering plywood is just going to make a breeding ground for mold and rot as moisture will find it's way in there. For that matter, cork is not the best for a bath, especially if it's a floating floor. Much better off with tile or vinyl.
But to level the floor, use some thinset as a leveling compound.
I'd put a vapor barrier down on the concrete, then one layer of treated plywood and one layer of standard plywood, and then refloor.
you could put down sand mix concrete, but then you haven't solved the vapor pressure issue, water will still rise up if it's wet underneath. and of course, you would need a bonding primer before laying the sand mix, which won't do you any good if there is a plastic vapor barrier.This message has been edited. Last edited by: swschrad,
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Posts: 5197 | Location: North Burbs, MN | Registered: Mar 14, 2007
Jaybee, thanks for reply and for the advice. I understand about the use of plywood not being a good choice. If I use thinset a my leveler won't it crack especially since I have build the floor up at least 1 and 1/2" to meet the existing floor?
Since you are going directly on top of a concrete floor the thinset will work as a leveler - even at 1-1/2". It is possible that this thickness will develop some small surface cracks as it cures but it will still work well as a leveling compound. You could also use a mortar mix for the major portion of the fill as it will be stronger, but either product will work.
We've used thinset as a leveling compound for these thicknesses without any issues many times, although we were always adding another thinset layer and tile as a finished floor.
what about the use of cement board? Has any one ever used it as a means to build a floor up? If I use the the vapor barrier between the existing concrete floor and my first sheet of treated plywood do I need to use a Hilti gun to keep my first layer from coming up or would you use construction adhesive?
Thanks to everyone that has contributed suggestions.
If you could forget about using tile on that floor One simple way to raise it and also have the floor feel warmer would be to lay a vapor barrier, use 3/4" Blue foam, then 3/4 T & G Advantech or Plywood.
Posts: 17889 | Location: Hartfield VA | Registered: Jan 31, 2004