# How much weight can sprayfoam hold?



## Bubski27 (Nov 9, 2011)

In my crawlspace, a hole was cut in the concrete for the main drainage pipe to leave the house. My problem is the hole cut is much larger than the pipe, so dirt from the outside flower bed is slowly making its way into the crawlspace. I'm gonna have to dig out my flower bed and was wondering if I can seal the rest of the hole with sprayfoam and if it can support the weight of the dirt I'll be putting on top. Or am I better off going with concrete. Thanks guys


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## Evstarr (Nov 15, 2011)

Hydraulic cement.


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## user1007 (Sep 23, 2009)

Spray foam is not really structural and among other things you may find animals gnawing it away to get inside so it would not even be a choice as a sealer for your cavity in my opinion. 

Abojet, from Abatron is a two part resin option to hydraulic cement. More expensive though. Excellent structural integrity though and a great product to work with. 

http://www.abatron.com/buildingandrestorationproducts/structuralcrackinjectionsystems/abojet1.html

Obviously you know that whatever you use you want to be sure and shop vac any of the loose dirt out before sealing the space.


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## Finpecia (Apr 3, 2012)

*nothing else*

Oh, that's Great Sir !!


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## Mikelite80 (Sep 1, 2010)

Sprayfoam is good for the last 1/8'' or so, but the majority of the hole you are going to want to fill with concrete. While Abatron products are good, it's overkill for your problem. Hydraulic cement is even a bit of overkill, it's advantages are it dries fast and can be used with wet areas.


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## Evstarr (Nov 15, 2011)

The specific property of hydraulic cement that recommends it for this application is that it expands slightly as it cures so is not likely to pop back of the hole at a later time!


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## Mikelite80 (Sep 1, 2010)

Real question is how big is the actual hole?


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## Thurman (Feb 9, 2009)

That certainly appears to be some type of "plastic" pipe, and with it being black I would venture to say DWV (drain, waste, vent). From what I know, DWV is thinner than sch. 40 PVC piping, which leads me to this: I have read some studies in which different types of "plastic" piping was subjected to being encased in concrete and to study the long term effects of being imbedded in concrete. One thing that came out of these studies very quickly was that certain "plastic" type piping could and would show degradation at the point the concrete touched the piping. Small pours of concrete, such as around a pipe as in this case, would actually move very slightly back and forth over time and rub a hole in the piping. This was found when tests were done with DWV used with concrete slab homes. I cannot remember all the details of this study, but there were recommendations as to "padding" around the piping _before_ the concrete was poured. Ironically, around here I see plumbers wrapping the DWV with plain ole' duct tape before pouring concrete. I'm just not convinced that this is the proper padding for this application. As far as using just foam to prevent the dirt intrusion: I would not trust the "Great Foam" type of stuff. I would use concrete and pad the piping with many wraps of duct tape if nothing better could be found.


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## Nailbags (Feb 1, 2012)

Mikelite80 said:


> While Abatron products are good, it's overkill for your problem. Hydraulic cement is even a bit of overkill, .


Over Kill is under rated!:thumbup:


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## Nailbags (Feb 1, 2012)

Thurman said:


> That certainly appears to be some type of "plastic" pipe, and with it being black I would venture to say DWV (drain, waste, vent). From what I know, DWV is thinner than sch. 40 PVC piping, which leads me to this: I have read some studies in which different types of "plastic" piping was subjected to being encased in concrete and to study the long term effects of being imbedded in concrete. One thing that came out of these studies very quickly was that certain "plastic" type piping could and would show degradation at the point the concrete touched the piping. Small pours of concrete, such as around a pipe as in this case, would actually move very slightly back and forth over time and rub a hole in the piping. This was found when tests were done with DWV used with concrete slab homes. I cannot remember all the details of this study, but there were recommendations as to "padding" around the piping _before_ the concrete was poured. Ironically, around here I see plumbers wrapping the DWV with plain ole' duct tape before pouring concrete. I'm just not convinced that this is the proper padding for this application. As far as using just foam to prevent the dirt intrusion: I would not trust the "Great Foam" type of stuff. I would use concrete and pad the piping with many wraps of duct tape if nothing better could be found.


That Black pipe is ABS DWV schedule 40 super strong stuff! It will out last any PVC pipe.


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