Pipes in foundation.

[Parrapit]

Hi Guys

I need some advice. If you cast a strip foundation say 750mm X 300mm deep and you have your nominal steel in and a pipe like a water pipe needs to run through it. On top of the foundation a foundation wall is built 110 brick 100 filled cavity and 110 brick to plinth level.

Now do you cast the foundation under the pipe and build the brick work around it and put lintels over the pipe so no pressure is on the pipe or do you just cast the pipe in or through the strip foundation and if the foundation moves or settles the pipe will also settle. Or will the wall act as a deep beam and carry the load over the "week point" and all is good. Soil bearing is pretty stable. Around 150 Kpa.

 

[racookpe1978]

Require than the pipe be put inside a "cover" or an outside pipe of slightly larger diameter. (A framed box would work, if your form crew doesn't like round things.)

(This isn't like a 1 inch cold water pipe running through a house wall into a crawl space.) What you want is to isolate the internal loads on the pipe walls (pressure, movement from heat/cooling, water hammer, vibration, etc.) from the external loads of the wall (ground movement, settling, etc.) on to the pipe. A double pipe then lets you insulate/foam, caulk or whatever the joint, and also lets you do the foundation and concrete work with affecting the pipe, nor without requiring the pipe be present, nor will the concrete wrk and construction be affecting (bumping, bending, twisting) the pipe.

 

[briancpotter]

In these situations I've simply required the pipe to be wrapped in some sort of compressible material to create a gap between it and the foundation, as racook says. I also might thicken the footing at the location of the pipe, depending on the size of the pipe and the thickness of the footing. Since your footing is rather thin, I'd recommend doing that as well.

Brian C Potter, PE

http://simplesupports.wordpress.com

 

[rjenyoy12]

Use pipe sleeve. The same principle applies to cables if incorporation in the foundation cannot be avoided.

 

[hawkaz]

Lower the footing if at all possible. It is bad pracitce to run a pipe through a footing. Also, sleeve it as noted in the other posts.

 

[NinerStruct]

I've used a each of the methods mentioned above. Like Hawkaz, I usually drop the footing whenever possible (interior shallow footings). If it passes through the middle of a trench footing or exterior foundation wall, I sleeve it as noted by racookpe. Or if it's right at the bottom at foundation bearing, I require void form or compressible material over the pipe/cables and have bent bars to continue the reinforcing over the top of the pipe.