DanFL
Member
I had a toilet moved for my bathroom renovation (house on concrete slab) and here is the new rough in that the plumber did. That's 3" PVC. He used some Ramboard to make a dam around the pipe when he refilled the concrete, so there is a void around the pipe about 1" from the pipe to the newly poured concrete. (I've never seen a toilet rough in done this way. I've always seen 4" stub out with solid concrete pour all around, but I'm not a plumber so maybe there was good reason for this...)
When I set the flange on the 3" pipe, any way I rotate the flange, the mounting screw holes line up either over the void, or only about 1/4" from the edge of the solid concrete. I'm concerned that it will just chip out as I drill the holes. There is some minor movement of the pipe + flange when I dry fit it, so it seems to me that I need to secure it to the slab. Can I get away without screwing it? I know those mounting holes on the flange are there for a reason, but are there any cases when I can get away without screws?
I was considering a couple options:
1. Attempt to drill and secure as best as possible with the current configuration. I could probably get at least 1, maybe 2 screws in this way if the concrete doesn't chip out.
2. Install a 3" to 4" coupling with 4" PVC stub out, and then fill the the void with concrete or thinset. Then I can cut that flush with the tile and install the flange inside the 4" sitting on top of the tile. This should eliminate any movement of the pipe and I have something solid to screw into. But... there may not be room for that as the hole is only 4" deep. I don't have a couple to confirm if this would fit.
Other suggestions are much appreciated!
When I set the flange on the 3" pipe, any way I rotate the flange, the mounting screw holes line up either over the void, or only about 1/4" from the edge of the solid concrete. I'm concerned that it will just chip out as I drill the holes. There is some minor movement of the pipe + flange when I dry fit it, so it seems to me that I need to secure it to the slab. Can I get away without screwing it? I know those mounting holes on the flange are there for a reason, but are there any cases when I can get away without screws?
I was considering a couple options:
1. Attempt to drill and secure as best as possible with the current configuration. I could probably get at least 1, maybe 2 screws in this way if the concrete doesn't chip out.
2. Install a 3" to 4" coupling with 4" PVC stub out, and then fill the the void with concrete or thinset. Then I can cut that flush with the tile and install the flange inside the 4" sitting on top of the tile. This should eliminate any movement of the pipe and I have something solid to screw into. But... there may not be room for that as the hole is only 4" deep. I don't have a couple to confirm if this would fit.
Other suggestions are much appreciated!