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Supporting Subfloor Over Basement Cleanout

782 views 10 replies 5 participants last post by  kjames05 
#1 ·
The cleanouts in my basement are all on the floor and right in the middle of what will be a bedroom. One of the cleanouts is about 1" below the surrounding slab and I'm struggling with a solution for how to support the subfloor above it. If left unsupported, I fear that area of the floor will be squishy.

My initial thought was to pour some sand and level it. That would likely support the subfloor initially but eventually the sand could spread out limiting the support long term.

I could also cut a piece of rigid foam to fit inside the area but it is not exactly 1" depth on all sides so there would be some spots higher than others which could lead to an uneven floor.

I'm curious to know if anyone has experienced this before and what other options may exist. Thanks in advance for any responses
 
#2 ·
Why not use cement? It can be smoothed to be perfectly level. If access is ever necessary, it can be broken up with a chisel. You could put down a piece of visqueen first to prevent the concrete from bonding to the floor, if that is a concern.
 
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#4 ·
This would be the best option but I'm not sure if it would meet code

More than one, one might be a back flow preventer and should be serviced from time to time.
I read the tiny writing on the cap and it is the backflow valve. I'll be creating an access hatch in the subfloor so it can be serviced.

What if I drilled some small holes through the subfloor and sprayed some Great Stuff? Even if you remove the access hatch and can't get it back into place because of the foam, you could easily redo the process.
 
#7 ·
If you are doing a subfloor and an access hatch, the solution is pretty easy. Glue on wood strips (shims) to the underside of the hatch until they contact the cleanout cover. This will provide midspan support to the hatch and make it stiff. I have done this before with access ports, and it works fine.
 
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#9 ·
I would put the shims under the middle of the hatch but far enough out so they contact the floor slab just outside the cleanout rather than on the cleanout itself.
 
#11 ·
Apologies for the late response on this. COVID has turned my life upside down a bit.

I used the aforementioned method of drilling through the subfloor and insulation before spraying some Great Stuff in the holes. I put a scrap piece of OSB over top to keep the foam from coming out.

I'm amazed at how strong the floor is in that spot and there's no squeaking. Not bad for an easy fix.

Sent from my SM-N960W using Tapatalk
 
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