More Plumbing Questions

[kimo wires]

When putting a 3" abs drain in under a slab, how much sand do you use under and on top of the pipe. Also any penetrations througt the slab get caulked? wrapped? I have a licensed plumber. Want to make sure it's all done right before inspector comes.

[EightFingers]

When I have questions like that, I call the county planning office (or where you get permits) . They should have someone that can answer your question.

[LavaZone1]

Hi Kimo wires, Sand below or above drainage pipe is a non-issue, what is important is that the piping or fittings should be not be embedded in concrete. Where it penetrates the slab it should be wrapped with foam insulation, I use "sill seal" from Home Depot, it comes in a blue roll.
After the slab has cured you could trim back the sill seal and fill with caulking to prevent intrusion of moisture or insects. EightFingers is correct about checking with the county, there could be some regional requirements.
UPC (uniform plumbing code) 718.1 ....sewer piping shall be laid on firm bed entire length...
And 312.2 ....No piping shall be directly embedded in concrete or masonary.
I'm sure your plumber knows what he's doing. I own a plumbing business in Portland, Oregon. I hope this helps.
Tom

[Sean]

Hi Kimo wires,

I designed water and wastewater systems on the mainland and the spec's/details indicated a "firm bed", but don't let firm be confused with rock. Drain pipe will fare better than pressurized pipe against rock, but I've overseen a couple of repairs where a single rock ~3" in diameter wore a hole through a pressurized watermain. My spec's called out 6" of bedding below if in non-suitable soils (rock or just rocky) and then 12" above and then above that 3 inch minus to the surface. The trick was in compaction around pipes, but even under slabs we allways compacted. Those spec's are designed to ensure a long life for sewer or watermain systems, both pressurized and gravity flow. Calling the county is allways a good thing and as a minimum always use pipe wrap for slab penetrations.

Cheers,

Sean

[LavaZone1]

Good point Sean, Being in the construction trade I assume others know the lingo. A "firm bed" is soil which is clean, compacted enough so the pipe won't sag below. UPC 315.4 ...free of boulders, cinderfill and other materils which may damage or break piping or cause corrosion.
Tom