Replace or re-level an uneven toilet slab on old wood?

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flamingpope

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Problem Details:
-Got myself a cape cod, wood beams with hardwood floorboards.
-Already removed floor tiles and toilet (1st floor).
-Toilet slab sits on top of sub-floor wood pieces that are nailed through the side of wood beams (not sitting on top of wood beams), this appears to be a patch from the previous owner. There are 3 gaps to envision between 4 horizontal beam supports, and each gap is where the multiple wood pieces are nailed sideways into the beam.
-Wood setup (except beams) has rotted and decayed into mud and rust due to a previous leak (leak now correctly patched), and has caused the slab to be uneven with the rest of floor boards, +- 0.5 inches, at an angle.
-Toilet pipe comes up through slab from basement and has soldered metal flange on top preventing direct take off of cement slab. (like a bolt coming up from the bottom and a nut soldered to the top).
-I would like to fix the angle, and fix it right so problem will be prevented for the next decade or two.

What's the best approach to this problem?

A few ideas I had were:
MyIdea1st:
1) Demolish/remove existing slab.
a) Replace sub-floor as needed, this time placing them on top of beam, not nailed in-between..
2) Re-pour/replace toilet slab.

MyIdea2nd:
1) Jack-up the slab from the basement using a car jack.
a) level cement slab.
b) Replace nailed sub-floor boards from the basement and nail them into the side, similar to previous owner.
2) Remove jack support.

Out of these 2 ideas or any you might have, what way is more right? I don't care about intensive labor, I just want to super sturdy seat for decades when finished.
 
Last edited:
I went ahead with Option 1, demolished the old slab setup. Which now that I've done it, I would recommend doing the demo to anyone in the future, as it allowed me to see other damages that were hidden from the top.

Also you feel better knowing the toilet won't just fall through your legs next time you take a seat :)

Procedure:
-Used a handheld jackhammer, and in about 10 minutes had the slab removed.
-hammer and crowbar the rusty nails, then work gloved the brittle/muddy/decayed wood pieces out.

I decided on new construction and relaid the missing floorboards.

Future:
-likely use thin-set around the toilet area of floor to stabilize and fill in the gaps.
-wonder board the entire floor/prime/self-level.
-Then finally on top of that, the toilet.
 
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