Looking for tips on air sealing tub plumbing slab on grade

I am looking for suggestions how to air seal around plumbing rough in for a tub on a slab. Normally we build a 12"x16" 2x box, bring our pvc into the box, usually leaving the pipe long and a little deep in the sand and pour our concrete around the box. Later when we set the tubs we dig up the pvc, cut to length, add trap, fill sand back in, then pour 1 or 2" of concrete to seal things up.
I would like to do a better job air sealing this location, everywhere else we are taping our poly to any penetrations through the slab.

Also we are installing 2" xps under the slab.

Any suggestions on how to approach this area?

Asked by kye ford
Posted Thu, 06/12/2014 - 20:41

Tags: General questions

1.

Kyle, It's funny you bring this up as it is the one detail you never see on sections through energy efficient slab on grade construction. Everyone is happy to show a single pipe sleeved and sealed, but the mess of drains under a tub…
My way round the situation has been to use drop-in tubs in a tiled surround - but to start with a 2"x6" base on the slab. The drain, overflow and trap all join in the space above the slab leaving a single penetration. The tub does end up quite high off the floor, but no higher than a claws foot.

Answered by Malcolm Taylor
Posted Thu, 06/12/2014 - 21:58

2.

Kye, let me know if you find details on how this is done because I'll need to figure out how to construct curbless shower pan (universal access designed house) in 4" slab / poly /4"EPS lay up with absolutely bomb proof leak resistance (getting soil wet below cannot happen).

Answered by Chuck Jensen
Posted Sat, 06/14/2014 - 10:02