You could jam a bunch of steel wool into it with a stick and then top it off with spray foam.

But you might also want to go around the outside perimeter of the house and look for any gaps between the foundation wall and the siding. Using a hand mirror and a flashlight may help. Any gaps also need to be filled.

The professional method would be to grout the hole shut.

I think if it was me, I would fill the hole with great stuff expanding foam until I was about an inch from the outside edge of the block on both sides and then grout over it to make it look nice. Let the foam act as a backer for the grout.

"The professional method would be to grout the hole shut."
WRONG!!!!

A Pro would know that the 3" hole is a feeble attempt at creating a code required sleeve for the pipe and filling the hole with grout would be totally prohibited.

Lazypup...I have several plumbing and natural gas pipes through a concrete wall. They were "sealed" closed with that quick setting cement. I was concerned there might be some corrosion action that could take place with the cement and the metal. Please advise. Should a gap be created by chipping away the cement? How do you seal out air and mice, caulk?

The plumbing codes specifically state that whenever a pipe is passed through a masonary wall(cement, concrete, stone or brick) the pipe MUST BE SLEEVED.

To create a sleeve you first install a short section of schedule 40 iron or plastic pipe at least 2 nominal trade sizes larger than the desired pipe and long enough to pass through the wall with 2" to 3" extending on either side. This "sleeve Pipe may be cast into the wall during the initial concrete pour or it may be installed through a bored hole later. The sleeve may then be sealed to the wall by any practical means whether that is masonary grout, cement, tar based substances or expansion foam.

The desired pipe is then passed through the sleeve and the space between the inner wall of the sleeve and the outer wall of the desired pipe is to be filled with expansion foam.

The concern is that pipe has a much greater coefficient of thermal expansion than does the concrete, by example, some pipes may expand by as much as 1/10 or an inch per degree of F differential. Consider a 100 foot long water line running from the street main or well to the structure. In mid summer the temperature of the water in the pipe and soil surrounding the pipe may be 55-60degF while in mid winter with frost in the ground the temperature of the pipe may be in the mid 30degF range. This means that the differential may be 25 to 30degF therefore the pipe may expand or shrink by as much as 2 or 3" per 100'. Understanding that the pipe is shrinking or expanding at a rate much greater than the concrete wall, it then stands that the pipe rubs against the concrete as it moves and even though the actual movement is very slow and almost microscopic in nature at any given point on the pipe run, nonetheless it does cause an undue stress and abrasion on the pipe wall which leads to premature pipe failure.

In addition, when the masonary material is in direct contact with a metal pipe there is a strong chemical reaction between the lime in the cement or concrete and the metal in the pipe which results in severe corrosion.

By making the sleeve larger, then filling the sleeve with the expansion foam the foam will allow the movement without undue damage to the pipe wall and the foam provides a dielectric barrier to help prevent corrosion.

Wow, thats a lot of information. I do appreciate the help from everyone. Thanks for your input. Great site!!

Does this mean my solution (steel wool embedded in expansion foam) was fairly good?

Steel wool would be fine for steel pipe but it would not be a good choice for copper pipe because the direct contact between the dissimilar metals could lead to electrolysis corrosion. If the pipe is a copper pipe I would suggest getting a few of those copper or brass pot scrubbers and stuff them in with the foam.

Yes, good information...!! Amazing how "wrong" things get done by the ones who are supposed to be the experts.

Lazypup - thanks as always for the informative post. How long has sleeving pipes that pass through masonry been code / standard practice? None of the brick wall pipe penetrations in my 50-year-old house have any kind of sleeving, and in at least one case, there HAS been a pipe failure as a result. (Pipe going to an exterior wall hose bibb)

Do I need to redo these? (Or have the gas company redo them in the case of the gas lateral)

- Water service, 3/4" copper cast directly into slab
- Hose bibbs (2), 1/2" copper through double brick wall
- Gas service lateral (indoor meter) through block wall, grouted in place
- Gas regulator vent pipe, same as the gas service lateral

I am not certain when it actually became code but I know for certain that it has been code since the early 1940's and I have found pipes sleeved in structures that were built as early as 1901.

That code requirement certainly wasn't enforced here in the 50s and 60s - my house and others in my neighborhood do not have any kind of sleeves on the pipes going through the brick walls. I know Virginia tends to be behind the current code cycles, but I doubt they were 20 years behind. It does seem from many comments that have been made here that this requirement is frequently not enforced.

So - how critical are these sleeves? For the pipes that have been cemented directly to the block walls for 50 years with no problems, can they be left undisturbed or is it your opinion that they're dangerous (especially the gas main - it comes through the wall BEFORE the regulator) and should be replaced by a more compliant installation?

Obviously any new pipes should be installed to the correct spec; this is a question about existing pipe that passed inspection when it was installed 50 years ago even though it has no sleeving of any kind.

Also, does this apply to electrical conduits? I haven't been able to find anything in the NEC about sleeving conduit.