Patching LARGE hole around Sewer pipe in Foundation.

I have a house with a very large hole around the sewer pipe. Pipe is copper, if that matters. the hole is from 2" to 6" around pipe, crudely cut out.

I need to fill this, since I've been getting water through it. I seems too large for hydrolic cement.

I was thinking of wrapping the pipe with rope and some plastic, then filling the hole with regular cement. Once the cement cures, pull out the rope and plastic. this should give me some space between the cement and pipe to seal with a good waterproof caulk (velkum 116, or other) or some hydrolic cement.

I plan on using a bonding agent to help the old and new cement attach better.

Any thought on my plan???

thanks.

Why not replace the bad section of pipe?

John

Because, apparently, it is NOT a bad pipe, but a bad "hole in the wall". If you can patch the hole with concrete, that should bond to the pipe so it will not leak.

thermal expansion

While copper seems to hold up well against the corrosive nature of concrete, there may be an issue with thermal expansion and abrasion if the pipe is totally encased, especially at points of entry and exit. I've copied a link to a site that may shed some light on the issue. Hope it helps.


http://www.copper.org/applications/plumbing/techcorner/problem_embedding_copper_concrete.html

thanks for the advice

Thanks for the advice. I'll try regular cement.

- Alex

after reading a bit more about how copper and concrete don't play well together, I've decided to try my rope/plastic method to make a gap for the foam sealant.

Is the polyurethane spray foam that I read about the same as the foam stuff you get for installing windows?

Why don't you just use the foam first, then grout around it...?

your local big box store should have a 5" wide x about 1/8" thick roll of foam wrap. Half a dozen wraps around your pipe will provide the needed expansion room -- and unless you've got a really bad hydrostatic pressure issue, should provide sufficient seal on it's own