pipe sleeve under footing 2

[dakota99]

A project is under constuction now where I orginally detailed all under slab plumbing pipes to be sleeved into either the foundation wall or the wall footing, depending on the I.E. of the pipe. now that all of the footings are poured it turns out that many of the pipes will now pass under the wall footings at 90 dergree angles. do I still need to provide a sleeve for this pipe? The pipe is PVC and will vary in size from 4"-12" and vary between 4' and just a few inches below the bottom of the wall footing. if a sleeve is requried, where can I find a detail of what this should look like?

 

[hokie66]

Are you the plumbing designer as well as the structural engineer? The plumbing designer should have some ideas about this.

Depends a lot on the type of soil you have. If the soil is moisture sensitive, then there can be complicated issues of isolating the pipes.

Where the pipe is very close to the bottom of the footing, I would use a void, maybe a piece of low density styrofoam, over the pipe. Have seen straw bales used for this purpose. As the pipe goes deeper, less chance it will be affected by footing load, as long as the trench is backfilled properly.

 

[msucog]

beware of the backfill associated with the pipes passing under the footing. i would also think about what the footing might do to the pipe either for support or for if the pipe were to crack (big costs to go back under the structure and fix it--as a geotech, i try to caution clients about putting water carrying pipes under footings--it's necessary but sometimes they are inadvertently located in more critical footing locations). for the pipes right under the footing, i like to see details of the footing either stepping down below the pipe or pipe the sleeve through a thickened footing. and watch out for those funny contractors that always seem to put the footings in first then come back and undermine the footing to install the plumbing pipe (they seem to have trouble compacting pipe trench backfill that is accessible much less if it's under the footing, so i wouldn't rely on them to do it correctly).

 

[DarthSoilsGuy]

i've seen it sleeved and backfilled with flowable fill or lean concrete underneath the footing.

 

[jike]

I agree with above comments.

Never run pipes below column footings! Always lower column footing below the pipe.

Run pipes thru foundation walls with blockout or sleeve and additional diagonal rebar. Provide sufficient distance around pipe to allow for settlement without the potential of rupturing the pipe.

Drop wall footing below pipe or use lean concrete fill to carry bearing stresses below pipe level. Provide sleeve or blockout with clearance for pipe as described above. For low bearing stress condition, footing may be stopped on either side of pipe. EOR or Geotech needs to evaluate this condition.

I hope this helps!