In my bathroom, the water supply and drain for the wash basin are exposed. The 3 pipes run along the wall at floor level, like this:

Drain situation

There's a small gap (a few mm) between the drain pipe and the wall. I suspect this has become a hideout for insects, so I want to fill it in.

I've got some tiling grout, would that be an acceptable material? The wall is concrete.

Second, the water supply pipes are copper. They're corroding where they run near the shower stall. I could cover the pipes with e.g. a plastic plate, but if the seal isn't perfect water can still get in.
Can I cover the pipes in tiling grout? Or should I use cement, or something else entirely? The object would be to prevent further corrosion, so the material shouldn't be porous.

1 Answer 1


I'd use "minimally expanding foam" rather than concrete or grout. Be sure to have plenty of ventilation and read the directions carefully... the stuff can make a helluva mess so cover/tarp/mask off anything you don't want to foam to stick to.

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