sleeving DWV under footing

[Brad Rowland]

I have had a hard time finding good info. on code requirements re: DWV under (perpendicular)footings.I was reading a thread on this site that had some pdfs posted by Jerry and I wanted to view them so I registered. I'm getting ready to build a house and, to me, the code is not clear. I'm hoping for some clarification here. It sounds like, according to Jerry, either I'll need a schedule 40 steel pipe long enough to be outside the 45 deg area under under the footing and two sizes larger than my pipe, or I need to go pay my engineer some more bucks for a footing design over the area. I'll try to search for the old thread so I can view the pdf.

On the same project, I will be running pex under the slab to an Island sink. I assume that I can just run my hot and cold 1/2" pex both through one piece of 3" PVC or ABS to get the job done there. 3" should be large enough to allow insulating the hot line to R3.6.

Any thoughts greatly appreciated. mean while I'll look for that old post

[Brian Hannigan]

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[Jerry Peck]

It sounds like, according to Jerry, either I'll need a schedule 40 steel pipe long enough to be outside the 45 deg area under under the footing and two sizes larger than my pipe, or I need to go pay my engineer some more bucks for a footing design over the area. I'll try to search for the old thread so I can view the pdf.

You are intermixing two different pipes:
- parallel with the footing
- perpendicular to the footing

Parallel with the footing, the piping needs to be outside that 45 degree angle (don't want the load of the house bearing on the piping).

Perpendicular to the footing, that piping just needs one of two things: a) a sleeve, minimum two pipe sizes larger than the pipe being protected, under the footing with no code prescribed length of the pipe beyond each side of the footing (I suspect the theory is that the load is on the sleeve, and if it pushes the sleeve down, the two-sizes larger allows for the sleeve to move down without creating pressure on the protected pipe), and that once the pressure is on the sleeve and not the pipe, the fact that the pipe is within - but perpendicular to - the 45 degree angle of load, that the pipe is sufficiently protected by the sleeve; b) create a load bearing arch in the footing which transfer the load from above the pipe to the footing on each side of the pipe, in which case the perpendicular to the footing pipe has no load on it (a relieving arch is simple to build and shouldn't take the engineer much to draw it up, probably already has a drawing for it.

If there is a pipe through a foundation wall, the same thing is required as if the pipe was under the footing - keep the load of the building off the pipe, see above.

[Brad Rowland]

You are intermixing two different pipes:
- parallel with the footing
- perpendicular to the footing

Parallel with the footing, the piping needs to be outside that 45 degree angle (don't want the load of the house bearing on the piping).

Perpendicular to the footing, that piping just needs one of two things: a) a sleeve, minimum two pipe sizes larger than the pipe being protected, under the footing with no code prescribed length of the pipe beyond each side of the footing (I suspect the theory is that the load is on the sleeve, and if it pushes the sleeve down, the two-sizes larger allows for the sleeve to move down without creating pressure on the protected pipe), and that once the pressure is on the sleeve and not the pipe, the fact that the pipe is within - but perpendicular to - the 45 degree angle of load, that the pipe is sufficiently protected by the sleeve; b) create a load bearing arch in the footing which transfer the load from above the pipe to the footing on each side of the pipe, in which case the perpendicular to the footing pipe has no load on it (a relieving arch is simple to build and shouldn't take the engineer much to draw it up, probably already has a drawing for it.

If there is a pipe through a foundation wall, the same thing is required as if the pipe was under the footing - keep the load of the building off the pipe, see above.

OK thanks Jerry. I find it odd the code wouldn't be more specific. By just reading it, I would have thought just two sizes larger ABS sleeve. I'm not sure they are enforcing that around here. Nobody seems to have heard of it. But it does make sense, so steel sleeve it is. I would also assume that no part of the unprotected pipe could be within the 45 degree area under the footing. In other words, the steel sleeve would need to be long enough to provide that no part of the ABS was exposed to the bearing area of the foundation.
By the way, does the same thing apply to my 1" copper water supply where it passes under the footing?

[Jerry Peck]

.. so steel sleeve it is.

The sleeve doesn't need to be steel, just an approved piece of pipe - PVC, ABS, CPVC, copper, or steel (but copper would be quite expensive, and steel will rust out).


I would also assume that no part of the unprotected pipe could be within the 45 degree area under the footing. In other words, the steel sleeve would need to be long enough to provide that no part of the ABS was exposed to the bearing area of the foundation.

The code, being a minimum code, doesn't require that.


By the way, does the same thing apply to my 1" copper water supply where it passes under the footing?

All plumbing piping, yes. You would need to protect the copper from the concrete anyway.

[Brad Rowland]

Thanks Jerry,
Huge help !

[Gunnar Alquist]

All plumbing piping, yes. You would need to protect the copper from the concrete anyway.

Jerry,

I had always thought that, but then I was told that was not true (don't remember when/where). I looked in the UPC and was unable to find it. Do you have a reference.

[Jerry Peck]

From the IRC (wording changes from edition to edition)

P2603.3 Breakage and corrosion


P2603.4 Pipes through foundation walls.
A pipe that passes through a foundation wall shall be provided with a relieving arch or a pipe sleeve shall be built into the foundation wall. The sleeve shall be two pipe sizes greater than the pipe passing through the wall.


(Note: 2009 IRC addressed "Pipes through footings or foundation walls." ... the "under footings" was dropped, so maybe "under footings" is no longer allowed? I'd have to do so further research to find out why that was done ... sometime ... maybe ... :) )


P2606.1 Sealing of annular spaces. and P2607.2 Pipes penetrating exterior walls. (these two address the question of other wall penetrations as does P2603.3)

[Gunnar Alquist]

Jerry,

Thank you. I guess I breezed past that. That also seems to answer the gas pipe question in http://www.inspectionnews.net/home_inspection/plumbing-system-home-inspection-and-commercial-inspection/49086-black-iron-gas-pipe-through-concrete.html?posted=1#post275669