Drill holes before or after?

[conner172]

I'm installing a brand new floor over brand new floor joists for my remodeled bathroom. The question I have is, once I lay down the subfloor, do I drill the holes for the water supply pipes and drain pipes before I pour the self leveling concrete, or after I pour the self leveling concrete? There will be a 4" hole for the toilet flange, a 2-1/2" hole for the shower drain, a 2" hole for the sink drain, and 3/4" holes for the water supply pipes.

 

[havasu]

Personally, i would drill, then pour the SLC afterwards. Just make sure to use spray foam around the holes, so the plumbing has room to breath.

 

[gxyzradio]

I'm installing a brand new floor over brand new floor joists for my remodeled bathroom. The question I have is, once I lay down the subfloor, do I drill the holes for the water supply pipes and drain pipes before I pour the self leveling concrete, or after I pour the self leveling concrete? There will be a 4" hole for the toilet flange, a 2-1/2" hole for the shower drain, a 2" hole for the sink drain, and 3/4" holes for the water supply pipes.

Drill the holes before pouring the self-leveling concrete. It’s easier and prevents cracking or chipping later. Just seal around the pipes after pouring to keep everything smooth.