My old, old basement leaks frequently with heavy rains. I've applied
Stop Leak patching. I've been advised to lay 6 mil plastic sheeting
before I lay the pressure treated 2x4 sleepers on top of the sheeting.
Question I have, if the basement floor leaks under the plastic sheeting
will it create mold? What will happen to the moisture?
Thanks.

I'd look a lot more into this and try to find the source and fix it.
Not sure but I think plastic sheeting is only valid if done in a crawl
space and fastened to the sill properly, which is quite a chore.

I can't see what the sheeting would do in your basement ?

Usually one starts by diverting the gutters away from the house, making
sure the ground slopes away from the house, etc.

Forgot to mention all that has been done. I'm ready to subfloor so I
can finish the room.
Thanks.

If the basement leaks frequently, I think you will need to do more than
lay down a vapor retarder.
If you must go forward:
The poly sheets are not water proofing.
They can be used as vapor retarders if the sheets are lapped 4" or more
and sealed one to the other and to the surrounding walls.
If water vapor accumulates, it can promote mold growth which will at
least smell.
If the basement leaks, the water has nowhere to go but to work its way
through the gaps and saturate the wood and eventually evaporate.
TB

"Pat" wrote
Forgot to mention all that has been done. I'm ready to subfloor so I
can finish the room.
Thanks.

You are far from being ready to lay a subfloor, or to finish the room.

Get a professional excavator out for an estimate. Sounds as if you need new
drain tile, with a sump pump, and some exterior waterproofing done.

Around here, they won't let you backfill with the same material once it's
dug up. A lot of clay was used as fill, which is a no-no.

If you insist on going forward, without correcting the problem you have,
you are inviting disaster.

Moisés Nacio wrote:
"Pat" wrote
Forgot to mention all that has been done. I'm ready to subfloor so I
can finish the room.
Thanks.

You are far from being ready to lay a subfloor, or to finish the room.

Get a professional excavator out for an estimate. Sounds as if you need new
drain tile, with a sump pump, and some exterior waterproofing done.

Around here, they won't let you backfill with the same material once it's
dug up. A lot of clay was used as fill, which is a no-no.

If you insist on going forward, without correcting the problem you have,
you are inviting disaster.



Pat - I whole heartily agree with Moisés. You will forever have
problems unless you FIRST have a dry basement BEFORE finishing. You may
need to excavate below footer, install a daylight drain if possible, use
a waterproof membrane on exterior, backfill with a water permeable fill
so that the water is directed away from your basement and into the
footing drain. I have this and it gravity drains to a 12' deep dry well
in the back yard. The dry well has an overflow about 30' from the house.
Sump pump and gutters also go to this dry well. My sump pump pit is
inside the basement and is NOT connected to the exterior perimeter
drain. The pump will pump out of the basement at the top of the basement
wall and gravity leads to the dry well. My sump pump NEVER runs. My
neighbor, 3 doors away, has the same house, same foundation but did not
seal the foundation or put in a dry well and his sump runs all the time.
Once it failed and he had 3' of water in his basement.

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