Floating Basement Floor

[jvh73]

I am planning to finish the basement of my new-construction, middle-unit townhome (SE Penna). It appears as though the basement has a "floating floor". There is a ~3/4" of foam around the perimiter of the floor at the base of the wall. (I'm assuming this is a sign of a floating floor"). I also have a working sump pump. My questions:

- Do I have to constuct "floating walls" which I've seen referenced in these forums to go along with my "floating floor"?
- Should this foam be left in place around the perimiter of the floor or removed to expose the 3/4" space in order to facilitate drainage in the event of a future leak?
- Given my lacation in the middle of a block of townhomes, which leaves me with only two exterior basement walls (one of which is covered by an extending garage and driveway above), is it worthwhile to seal the concrete in the basement prior to finishing? The exterior of the foundation has some sort of rubberized shell which is supposed to prevent leaks.

I appreciate any input.

J

[Rich]

The 3/4" foam is more than likely an expansion joint, which is not a floating floor. Expansion joints allow the slab to expand and conctract.. not heave or drop. The expansion joint should be left in place.
In regard to floating walls - it really depends on what the soil is like underneath your concrete slab. If it's heavy with clay then yes you should construct floating walls.. if it's more sandy loam then you wouldn't need floating walls.

[jvh73]

Thanks for clearing that up. Are you at all familiar with the rubber coating applied to the exterior of the basement walls? Would the application of a sealant product on the interior of the walls be redundant given the presence of this rubber barrier?

Thanks again.

J

[Rich]

I imagine the rubber coating (tar) is a damp proofing product. I say damp proofing because it's not waterproofing. Waterproofing is a whole other ball of wax and is much more involved than a simple coating. For the interior side, if you choose to do so, there is an "expanding" type paint that can help with interior moisture on concrete and masonry walls. Your LHS should be able to find something for you. The name of it escapes at the moment.