How do you seal a cast iron pipe coming through concrete when the pipe
penetration is below the waterline???
I am going to pour concrete around the shower drain pipe in the
concrete slab and create a drywell. However, the rusty cast iron pipe
will go through the concrete slab below the water line (during the
rainy season). I need to seal the seam between the cast iron pipe and
concrete so no water will infiltrate into the drywell I am creating. I
have no basement; this is on the ground floor of my home.
Any and all valuable advice is welcome and would be greatly appreciated!
Unless I misunderstand something, nothing you do will stop the water for
And a cast pipe that is already rusty and sitting in ground water is not
going to have a long life.
Why do you need a drywell there ? (shower base ?)
Can you change the pipe to PVC ?
you could try the expanding foam in a can they use for windows/doors
This is exactly what I was going to recommend. It's made to be
installed in water. I have used it, it works great. However, I would
not try to use it under a few feet of water, but a little wet is fine.
The stuff is extremely hard too. It's costly though, so dont try to
pour a basement floor with it.
I'm a little confused. If the line exits the concrete below the
water table, how can anything about it possibly function as a dry
Gray water plumbing is illegal in many/most jurisdictions.
To seal a pipe penetration in a concrete wall: drill an
appropriate sized hole to allow about a 1/2" annular space.
Insert backer rod to proper depth around the pipe, caulk with one
or 2 part polyurethane, repair wall waterproofing membrane as
None of the expanding foams are waterproof to my knowledge.
Cementitious grout packs do not allow for any differential
movement between dissimilar materials (cast iron and concrete or
pvc and concrete)
(top posted for your convenience)
Keep the whole world singing . . . .
DanG (remove the sevens)
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