Sealing around concrete form openings

blue_can · 11-25-2009, 01:58 PM

I'm about to pour some concrete for a small wall footing. I have run some piping (landscape irrigation PVC piping as well as electrical conduit - gray PVC) through openings in the form and these will be embedded inside the footing. I'm wondering how best to seal around the gaps between the hole for the piping in the forms and the pipe itself to prevent wet concrete from seeping out during the pour. Would some outdoor silicone be sufficient or should I be looking at something stronger.

Bondo · 11-25-2009, 03:29 PM

Ayuh,... Don't bother... It won't seep much anyways, the aggregate will plug it up...

**Gary in WA** · 11-25-2009, 03:42 PM

If its a big hole, some tin screwed to the inside form would work, or 1/4" ply. Usually, you set a section of pipe cut to the wall or footing form thickness with nails through the outside form to hold it in place. After removing the forms, install a smaller size pipe through the concreted one.
Be safe, Gary

Maintenance 6 · 11-25-2009, 04:20 PM

If it's for a footer, nobody will see it. If you make it too tight, you just make the forms harder to get off. Unless the holes are way over cut, it won't make a difference. The concrete won't leak out very much.

blue_can · 11-25-2009, 07:40 PM

Okay thanks for the replies. It is not overcut by much - about 1/4". I'm not concerned about the look since nobody will see it. I was more concerned about too much concrete seeping out and affecting the level but I guess the aggregate will plug it up anyway.

11-25-2009, 01:58 PM	#1
blue_can Member Join Date: Aug 2009 Posts: 35	Sealing around concrete form openings I'm about to pour some concrete for a small wall footing. I have run some piping (landscape irrigation PVC piping as well as electrical conduit - gray PVC) through openings in the form and these will be embedded inside the footing. I'm wondering how best to seal around the gaps between the hole for the piping in the forms and the pipe itself to prevent wet concrete from seeping out during the pour. Would some outdoor silicone be sufficient or should I be looking at something stronger.

11-25-2009, 03:29 PM	#2
Bondo Master General ReEngineer Join Date: Dec 2007 Location: Chaumont River, Ny. Posts: 3,175	Sealing around concrete form openings Ayuh,... Don't bother... It won't seep much anyways, the aggregate will plug it up...

11-25-2009, 03:42 PM	#3
Gary in WA Moderator Join Date: Mar 2009 Posts: 8,843	Sealing around concrete form openings If its a big hole, some tin screwed to the inside form would work, or 1/4" ply. Usually, you set a section of pipe cut to the wall or footing form thickness with nails through the outside form to hold it in place. After removing the forms, install a smaller size pipe through the concreted one. Be safe, Gary __________________ Clothes taking longer to dry? Clean the dryer screen in HOT water if using fabric softener sheets. They leave a residue that impedes air-flow, costing you money. Clean the ducting in the last six months? 17,000 dryer fires annually!

11-25-2009, 04:20 PM	#4
Maintenance 6 gravity always wins Join Date: Feb 2008 Location: Central Pennsylvania Posts: 2,417	Sealing around concrete form openings If it's for a footer, nobody will see it. If you make it too tight, you just make the forms harder to get off. Unless the holes are way over cut, it won't make a difference. The concrete won't leak out very much.

11-25-2009, 07:40 PM	#5
blue_can Member Join Date: Aug 2009 Posts: 35	Sealing around concrete form openings Okay thanks for the replies. It is not overcut by much - about 1/4". I'm not concerned about the look since nobody will see it. I was more concerned about too much concrete seeping out and affecting the level but I guess the aggregate will plug it up anyway.

Sealing around concrete form openings