# Sealing pipe through block foundation



## terri_and_jj (Feb 24, 2008)

Just get some foam in a can. the stuff works great, but there are a few things to keep in mind. 

a. the regular stuff really expands as it cures, so use it sparingly or you'll end up with a big mess. i've seen people buckle windows and blow a hole in drywall with spray foam.

b. this stuff cures with air, so if you try to use too much it will never fully cure in the middle. the rule of thumb is if you make a glob bigger than your fist, the center won't cure. so this means do it in stages if you are filling a large void. you might need a couple cans, because once you crack a can, even if you don't use the whole thong it sometimes cures in the nozzle. i use the big cans with the screw on gun, so i really don't remember if you can use half a straw can today, and the other half tomorrow.

c. cure time is much faster in warm weather than cold, so make sure you give each application ample time to cure based on the temps you are dealing with


once it cures you can trim it with a knife, sand it, and even paint it . painting will give it some UV protection on the exterior side, and make it last longer. you can also buy it in black, but not sure if the local Depot or Ace hardware will have black foam on the shelf


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## kboorman (Mar 8, 2008)

Is the expanding foam waterproof?
I thought about using that stuff, but it seemed to be a less durable solution.


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## terri_and_jj (Feb 24, 2008)

i can't remember the exact spec, but i remember hearing or reading that it's not technically waterproof, but it will hold back flowing water, something like that.

what you could do, if you are really worried about it, is use expanding foam to fill the large portion of the void, that patch the last couple inches around the pipe with cement


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## Bondo (Dec 8, 2007)

Ayuh,....

1/2" pipe measures about 3/4"OD,.....

Punch a 1" hole thru, insert the pipe,+ pack Hyd. Grout into it.....

It'll last darn near Forever....


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## AtlanticWBConst. (May 12, 2006)

Vote: Grout or cement the gaps/spaces. 
Once cured, go back and seal the materials where they meet together with a good NP1 caulk (polyurethane based caulking).


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## kboorman (Mar 8, 2008)

Bondo said:


> It'll last darn near Forever....


Thanks for the responses guys, that's pretty much what I'm after. I don't like doing things twice so I don't mind the time to do it right the first time. Hydraulic cement it is. 
Only problem I have is my biggest bit is 3/4" and I don't feel like buying another right now. I guess I could drill through and carefully chisel it out to 1" or so?


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## js2743 (Feb 13, 2008)

if you have a 3/4 then why would you want to make it 1" for when you only need 3/4 then you have no hole to fix.


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## kboorman (Mar 8, 2008)

I figure a hole the exact size of the pipe won't allow me to get the cement (or anything else) in there to seal it. I'll probably taper the hole outward on each side of the block so I can get a little more bonding surface as well.


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## AtlanticWBConst. (May 12, 2006)

Originally, I had thought (assumed) that the pipe and the hole were bigger. 

Use a polyurethane sealant. You need to seal the concrete from weather erosion.


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## Bondo (Dec 8, 2007)

Ayuh,.....

If it's that Tight a fit,.... Just caulk it....


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## kboorman (Mar 8, 2008)

Thanks again guys. The pipe wouldn't go through the 3/4" hole (I guess I could've hammered it through though), so I enlarged it a bit. The way it stands now, the hydraulic cement should be fine to seal it but you think that needs to be protected from erosion?


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## AtlanticWBConst. (May 12, 2006)

kboorman said:


> .....the hydraulic cement should be fine to seal it but you think that needs to be protected from erosion?


Yes. 

FWIW: It's something I know can happen (When the area is directly exposed to the weather and rain) I have seen it happen, while doing construction evaluation inspections.

The grout or cement is fine on larger gap areas, but the point where the two materials meet should be caulked. 

Since you don't have a larger gap, just use the polyurethane caulk.


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## kboorman (Mar 8, 2008)

Gotcha.
Thanks, Kirk.


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## majakdragon (Sep 16, 2006)

I would use a silicone caulk. The concrete will move or the pipe will expand and contract from changing temperatures. This could rub a hole in the pipe. Not fun to get a gas leak inside a concrete block. Silicone will allow for movement.
Sidenote: This is another one of those instances where the Code is different. Most areas require black iron pipe for gaslines since the galvanized coating can flake inside the pipe and clog burner orfices. Florida was the first place I saw galvanized used on gas services. In Ohio, it was not permitted.


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## kboorman (Mar 8, 2008)

majakdragon said:


> ...Most areas require black iron pipe for gaslines since the galvanized coating can flake ...


Hmm, I wasn't aware of that. Galvanized is permitted here in PA and I went with it because it was going to be partially exposed to the elements (a whole 4" of it  ). 
For my application the price difference was negligible, so I figured it was the better choice.


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## AtlanticWBConst. (May 12, 2006)

majakdragon said:


> I would use a silicone caulk. The concrete will move or the pipe will expand and contract from changing temperatures. This could rub a hole in the pipe. Not fun to get a gas leak inside a concrete block. Silicone will allow for movement.
> ...


That is why he needs to use a polyurethane caulk. NOT silicone. 
Polyurethane caulk/sealant is the industry standard for such an application. 
It is permenantly flexible.

Example: http://www.basf-cc.com.au/sealant/index.htm


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## majakdragon (Sep 16, 2006)

Kboorman, Code variations are the reason I usually tell people to check their LOCAL code. Codes are not the same nationwide and even National codes can be added to by local authorities.
Atlantic, I do hardly any residential work and most commercial jobs require a sleeve through any masonary walls for gas piping (inside or out). Guess the contractors I have worked for had silicone "on hand" and gave it to us to use. Not saying it's right, just what we were supplied with.


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## AtlanticWBConst. (May 12, 2006)

FWIW: My point about the polyurethane sealant is actually based on industrial construction and multi-unit construction work that we do. 
On the Industrial Work, EVERYTHING (all work) is "held under a microscope", by the engineers.


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## majakdragon (Sep 16, 2006)

I agree. When i did a job at Post Cereal, they supplied a foodgrade and insect resistant product for between sleeves and piping. Disney (strangest inspectors I have ever seen) also required a rubber type product and the space needed to be completely filled inbetween the pipe and sleeve (not an inch or two at each end).


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## Maintenance 6 (Feb 26, 2008)

Urethane caulks will bond well to the masonry. Most silicones have serious adhesion problems when it comes to masonry. If you are caulking the pipe to the masonry use urethane, something like Sikaflex. If you are sealing sleeve to pipe, use silicone. Wipe the galvanize piping down with a solvent first as it usually has an oiley substance on it that will prevent either one from bonding well to it.


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## AtlanticWBConst. (May 12, 2006)

Maintenance 6 said:


> Urethane caulks will bond well to the masonry. Most silicones have serious adhesion problems when it comes to masonry.....


Yes, Sika is another very good brand of urethane caulk and sealant.

To add to the point of adhesion: 

Composite trim boards, like AZEK, Koma board, and others, require a urethane caulk (or a polyurethane caulk).
Silicone isn't even recommended, as it is not proven that it will stick, with the heavy expansion that composites experience during seasonal changes.
(We had to do a construction inspection & evaluation at one complex, only a year old, where the composite trim board siding was all separating, due to use of silicone caulking, and latex caulking)


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## MarionDivFan (Apr 14, 2015)

*Similiar A/C line penetrations/sealing through block walls*

I found this threat very informative, as I have a similar problem that needs repair. 

I have A/C lines from my outside compressor that go into my basement here in central OH...The old black sealant around where it enters into the conc. block wall is loose (I can actually take it off as it's not attached to anything), and I'd like to remove & replace it ...

From previous posts, sounds like using the expandable foam to fill in the inside void is first, followed by a polyurethane caulk would follow on the outside

Thanks again...
Rich


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