# Leveling Basement Floor Rigid Foam



## mdenis (Sep 6, 2009)

I'm making plans for a finished basement. I'd like to begin the insulation as shown in this video. The video shows rigid foam boards on the slab and around the walls, the foam on the floor is then covered with a sheet of chip board which acts as the subfloor. The rigid foam acts both as the insulation and vapour barrier.

My question is this:

The floor in the video is fairly obviously level however my basement floor is not, my floor slopes toward a drain. Would it be possible to shim the rigid foam as it is put in place (perhaps with multiple levels of tar paper?) resulting in a level floor to place the chip board on? If this is not a possible solution I imagine that I would use shimmed sleepers with rigid foam between each.

Thanks for your advice.


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## Bob Mariani (Dec 1, 2008)

shim with stone dust or small gravel which will allow the base to still drain as it is now.


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## mdenis (Sep 6, 2009)

hmm...good idea...so I can build up the whole floor to a level surface with this method?


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## Bob Mariani (Dec 1, 2008)

yes you can. Use a straight 2X4 as a screed to level to set lines.


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## mdenis (Sep 6, 2009)

So once complete the rigid foam will essentially be floating on the small gravel then the chip board is fastened to the concrete using a hammer drill.

Should I be worried about the floor becoming uneven over time (maybe the gravel penetrates the foam as it becomes compressed with use)? Have you seen an example of this method utilized? Can you direct me to it?

Thanks for your input Bob.

Matt


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## Bob Mariani (Dec 1, 2008)

the foam and plywood will distribute the weight evenly so no settling will occur. No samples. I would level the floor with SLC (self leveling compound) but this would be costly. Since you addressed a draining issue and uneven floors I suggesting something would address both. I have leveled large basement with this method using sand, radiant heat pipes, insulation and then poured concrete. If the gravel was interacting with the foam the concrete floor would settle or crack which I have never seen happen.


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## mdenis (Sep 6, 2009)

I appreciate your response Bob :thumbup:


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