I would have thought I'd be able to do an image search for help figuring this out, but so far I've been unable to put together a set of keywords that looks like my situation.

I have a two-story house with a crawlspace, built in 1985. The foundation, viewed from the outside, is 8x2" bricks. From inside the crawlspace, the foundation is 16x8" cinderblock. The total thickness of the foundation wall seems to be about 7" or 8". For the life of me, I can't figure out how this wall was constructed. Every common brick and cinderblock I see in raw form has 4" and 8" of depth, respectively, meaning this wall should be at least a foot thick. Is one (or both) of the surfaces a facade? What's holding my house up?

  • Can you clarify? So long as the walls are thinner than the cinderblocks, then (hope there's a sill plate on top of the blocks) the walls just need to sit over the blocks. Commented Mar 18, 2020 at 19:52
  • ...4 inch block (4, 6, 8, 10, 12 are all common block thicknesses) plus 4 inch brick add up to 8 inches. Veneer brick down to 1/8 inch thick is also available. Try looking at a better stocked place (such as a masonry supply yard) to see what you have not seen.
    – Ecnerwal
    Commented Mar 20, 2020 at 2:54

2 Answers 2


Wild guess (without photos):

  • 6" concrete block structure (common for residential foundations--4" is mostly used for a shorty garage wall base and cases where actual brick ledges are present)
  • ~1" thin brick veneer outside

You may also have a 6" foundation that transitions to a 4" block behind a full brick veneer.

You should be able to determine brick thickness at corners or penetrations. That'll tell us a lot.

  • +1 a number of good reasons for variation in foundation thickness.
    – HoneyDo
    Commented Mar 18, 2020 at 19:34

Presumably, your house is being held up by the actual foundation that you'd have to crack open the slab to see.

It goes like this: Excavate the entire footprint. Then dig additional trenches, to below the frost line (usually several feet below the slab), where the foundation walls will go. Set forms and pour foundation. Pour slab using foundation as form (ideally 6" thick; 4" will do, any less will crack). Build cinder block walls. Waterproof them and backfill. Build house and clad as specified, in your case, with facade.

  • If there is a slab Commented Mar 18, 2020 at 19:50
  • 1
    Well, if there's no slab, then go down there, dig a hole, and look ;) because, actually, there could be nothing.
    – Mazura
    Commented Mar 18, 2020 at 19:51
  • True that! ..... Commented Mar 18, 2020 at 19:57

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