GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Floating basement walls

Zephyr7 | Posted in General Questions on

I saw this “floating wall” in a basement in Aurora, Colorado, which is a bit southeast of Denver. Does anyone know the reasons behind this type of basement wall construction? I haven’t seen this before. I’m told it’s to deal with slab movement, but movement like that I’d think would also mess with the foundation itself, I’m not sure what the point would be. In my usual area, basement walls are built directly on the slab. 

This “floating” wall is suspended from the ceiling and has something of a double bottom plate with a pin holding the upper “bottom” plate but allowing for vertical movement. 

Bill

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.

Replies

  1. Expert Member
    Malcolm Taylor | | #1

    Bill,

    Without knowing more it seems like an ingenious response to problem the doesn't exist.

    1. Expert Member
      Zephyr7 | | #2

      After some more reading, apparently the areas around Denver tend to have a bentonite containing soil that expands with moisture content, causing heaving issues. Strange, but interesting, stuff. Looks like the floating wall framing is a code requirement here.

      Bill

      1. Expert Member
        Malcolm Taylor | | #3

        There is probably some really interesting detailing that has t0 go along with that. Things like expansion couplings on plumbing, how you handle internal point-loads, and God knows how you deal with the drywall and baseboard trim.

        I don't know much about expansive soils, but the walls seem to assume that only the slab will move, not the foundation. Surely it would make more sense to design a foundation that would either stay put or all move at once?

        1. Expert Member
          Zephyr7 | | #6

          Apparently the foundations in these cases are built on piers instead of footings. I’d still think that there would be a tendency for things to move independently and cause problems, unless the piers are going really deep or even to bedrock, commercial style.

          Bill

  2. But Why? | | #4

    My driveway slab on clay will move up and down 1-2 inches depending on soil moisture as well as seasonally with temps but my house and basement slab don't do that dance. Seems like if you had good moisture control, the soil under a basement slab would't vary enough in moisture content to expand that much.

    But, yes, of all the clays, bentonite is actually used to seal ponds and dams because it expands so much.

    1. Expert Member
      Malcolm Taylor | | #5

      Replacing the sub-slab fill with something non-expansive makes more sense to me than floating the walls, but maybe there is something more in play?

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |