I have a gas pipe that comes through my poured concrete foundation about 12 inches off the ground:
It is not sealed around the pipe on the outside. The gap is definitely large enough for insects to get through, and maybe small mice so I want to seal it up.
Googling this, I see a lot of mixed info – some ppl are saying expanding foam or caulk are OK, others are saying you MUST have a special sleeve. However, the sleeve stuff seems to be specific to underground penetrations through the wall?
So, I'm wondering is it OK to put expanding foam or caulking around that? Should I do just one or the other? Or should I pump foam deeper into the hole as thermal/ air insulation, and then after that's hardened, caulk around the outside for water seal? Or should I use some other product entirely?
Note that this is already in place, so something like a sleeve that needs to be put in place at the time the line is run is not an option.
Thanks.
Update: Based on the comments and suggested duplicate, I'll clarify that this pipe goes through a concrete tunnel at least 10 inches long. The suggested duplicate may be a solution, but if it is I need some clarification on whether I should be trying to get duct seal to completely fill that tunnel around the pipe. Or do I just seal the outside with duct seal? If the latter, then that means the rest of that tunnel is just empty. Does that matter?
Best Answer
I would use "duct seal". It's a putty-like material that's a bit sticky. You'll find it in the electrical department. It's much more robust than foam.
Caulk would be difficult to work with on a gap that big and would be more difficult to remove if you had to do any modification later. You could probably get good results with silicone, though. I'd go with clear or light gray. Don't use latex as it shrinks badly.