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Community and Q&A

Floor system on Slab foundation

Sheldon Hobman | Posted in General Questions on

Hello everyone, quick back story. I’m building a home at a estates that’s close to a riverbank. So because of potential unstable soil you need a Engineered Raft Foundation. And to cut back on overhead costs we decided to go with a Engineered raft Slab Foundation instead of a dug basement, and then we started looking at Radiant heat to put right in the slab which ended up being to expensive.

So here is my question, we need to go with forced air and we have a Slab foundation. At the current moment we are thinking of putting a open web engineered floor truss on top of the slab so we can run ducting. Is there any other options we could do that would be more cost effective.

PS. Many might suggest a crawl space but we have already had the slab engineered

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  1. Stephen Sheehy | | #1

    Sheldon: We need to know where you live (what zone) and what your expected heat load is. Ft. Lauderdale FL has different heating requirements from Ft. Kent ME. In many locations, ductless minisplits are a cost effective solution.

  2. Sheldon Hobman | | #2

    Hi Stephen, this would be in Saskatoon, Saskatchewan Canada

  3. GBA Editor
    Martin Holladay | | #3

    If it's a two-story house, you can run ducts through open-web floor trusses.

    If it's a one-story house, you can install ducts in an unvented conditioned attic.

    Or, as Stephen notes, you can use ductless minisplits.

  4. Expert Member
    Malcolm Taylor | | #4

    Having a slab at grade doesn't preclude building a crawlspace. You can build knee walls around the perimeter and intermediate ones in the interior to carry the floor joists.
    The two downsides of either a crawl or your suggested floor trusses are cost and that they raise the first floor higher above the surrounding exterior grade.

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