Hello all, I'am installing DWV pvc inside a foundation before the slab is poured. Are there any special considerations needed as far as support or can the pipe just be laid in the dirt/gravel and then stub up above the slab line?

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I'am installing DWV pvc inside a foundation before the slab is poured

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Are you installing the line inside the foundation or through it?
Let me know, Tom

Pipe has to be supported so it won't bend under weight of the concrete. We always try to excavate the way so our pipe lays directly on solid dirt. However, if it ends up higher than you can support it every 6' or so with concrete blocks - or break a concrete block and use the pieces to build up under the pipe as needed. We also use short pieces of rebar to keep main pipe from shifting during pour.

It makes for a good practice to wrap pipe with plastic wrap where pipe penetrates slab or where pipe becomes in direct contact with concrete. It prevents pipe from breaking should there be any future earth movement or house settling. Since my area of operation is in an active seismic zone - wrapping pipes is required by the Code.

Enclosed photo shows one of our recent installations. What you are looking at is a ABS rough-in for 3-unit bathroom: toilet in front left ( hidden behind 3" vertical clean-out ), shower on the right in "tuff-box" and sink in the back with 10' of vertical test pipe (... converted into sink vent later ). Pipes are filled with water and entire project just passed City inspection. This job is ready to be poured...

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Originally Posted by speedball1

Are you installing the line inside the foundation or through it?
Let me know, Tom

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The 4" line from the septic will pass through the block wall and under the slab then 90 up at various spots through the slab to connect to a shower,sink,toilet.

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Originally Posted by Milo Dolezal

Pipe has to be supported so it won't bend under weight of the concrete. We always try to excavate the way so our pipe lays directly on solid dirt. However, if it ends up higher than you can support it every 6' or so with concrete blocks - or break a concrete block and use the pieces to build up under the pipe as needed. We also use short pieces of rebar to keep main pipe from shifting during pour.

It makes for a good practice to wrap pipe with plastic wrap where pipe penetrates slab or where pipe becomes in direct contact with concrete. It prevents pipe from breaking should there be any future earth movement or house settling. Since my area of operation is in an active seismic zone - wrapping pipes is required by the Code.

In enclosed photo showing one of our recent installations. What you are looking at is a ABS rough-in for 3-unit bathroom: toilet in front left ( hidden behind 3" vertical clean-out ), shower on the right in "tuff-box" and sink in the back with 10' of vertical test pipe ( ... converted into sink vent later ). Pipes are filled with water and entire project just passed City inspection. This job is ready to be poured...

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Thanks for the help. You answered my question.