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How to landscape around a cantilevered floor?

Lainers | Posted in General Questions on

The house we moved in to 15 months ago is one of many with the same floor plan in our neighborhood. Each of the houses has the living room floor as the cantilever floor that hangs over the basement concrete wall roughly 20″ x 10′. I’ve noticed some houses in our neighborhood have landscaped around this cantilevered floor with retaining walls and have created garden beds under and around it. That doesn’t seem like a great idea to me but it looks nice because it hides the fact that the floor is cantilevered. Why someone would build all of these houses in this way is beyond me, but it was the 50’s and I’m sure no one thought too hard about things like this at the time.

We’ve run into problems with this cantilevered floor. We had our basement gutted due to mold so the ceiling that was once there was gone. One summer day I noticed light peeking through up into the cavity between the floor joists. Sure enough a chipmunk or some other critter had chewed through the wood subfloor and was attempting to make a nest. This area is really hard to get to between the joists so we did our best to nail a piece of plywood over the hole and spray foam around it. My spouse and I recently insulated the area that over hangs. First we spray foamed the seams then added insulation, then a vapor barrier. I didn’t think that was the best idea because I am really paranoid about condensation and moisture because we already had a mold issue when we moved in. I’ve seen online that using block foam is the best way to insulate and then use R30 batt insulation in the middle of that. 

Did we insulate our cantilever floor incorrectly? Is there anything we can put underneath it like landscape rocks, etc, to deter any animals from trying to take shelter underneath it? We have a definite chipmunk problem in the front yard.

Thanks in advance and apologies for my lack of technical lingo.

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  1. user-2310254 | | #1


    Maybe you read this article:

    Air sealing is crucial to prevent air leakage. It would be helpful if you could tell us your climate zone and the particulars of your cold-floor stackup (how much insulation, what type, etc.).

  2. GBA Editor
    Brian Pontolilo | | #2

    Hi Lainers.

    Here is a similar article to the one Steve linked to, just a bit more recent and found here on GBA: Insulating a Wood-Framed Floor Assembly.

    Also, like Steve, I'd like to know more about how you insulted the cantilever. But briefly, to keep critters out, you can cover the bottom of the assembly with a sheet good like plywood, OSB, or ZIP Sheathing, which you could also detail as an air barrier.

  3. Andrew_C | | #3

    Outside, you want clearance to the ground, as much as possible. This helps the area dry out, helps reduce the attraction to skunks and opossums (and chipmunks), makes it easier to clean out the leaves and other debris that will blow in, etc. If you put some sort of bed underneath the window, make it stone, not bark or other organic matter that attracts ants and other bugs. More clearance to the ground also makes it easier to inspect and repair later.

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