DWV fittings allowed in concrete?
We are pushing exterior wall of bathroom out. The existing bathroom has a basement below. The new part is slab which will sit about 4' above grade. The new slab will have tub and toilet. Tub has 2" drain, toilet has 3" -- both have separate 2" vents that will penetrate through the slab (inside future fixture wall for tub/shower - 2x6 studs). My DWV plans were approved and I have a permit already, but I have a few questions about the implementation...
Question 1: Can DWV fittings on the vent be encased in the concrete? The final vent tees below the slab look like they may penetrate a bit into where the concrete will be. Is it sufficient to just wrap the pipe and final fitting with PVC pipe wrap or foam or something?
Question 2: Do I need to wrap the final 4" toilet stub out? I was planning on using the flange that goes inside the pipe, but do I still need to wrap for expansion allowance?
Question 3: A duct needs to pass under the slab. This duct is an air intake for furnace which previously emerged from the side of the existing cinder block wall. Are there any special concerns in doing this? The concrete folks were going to do this part but just wanted to make sure its done correctly... (recall the slab is well above grade.)
Question 4: There is a copper pipe that needs to pass under the slab -- its an overflow route from the hot water heater -- so its not a supply line. Is this pipe still subject to the "no fittings under slab" rule and does it need to be type K or L (as opposed to M)? I think it still needs to be wrapped in PVC tape though -- is that right?
Sorry for the numerous questions, but hopefully any answers will help more than me...