Sealing closet flange hub to slab soil pipe stub without welding the joint with PVC cement
Posted by Allan Chertok on February 09, 2003 at 21:40:11:
I am about to install a hub-style closet flange to the 3" PVC soil pipe stubbed out of a concrete slab.
As owner/builder I am reluctant to permanently weld the flange hub to the stub with conventional PVC
cement as it would be near-impossible to replace the flange in the future without breaking the stub.
Moreover, there is a subfloor built over the slab on sleepers topped with substrate and tile making access
to the stub area impossible without major floor surgery!

QUESTION: Would a reliable seal against waste water and sewer gas be obtained by applying a
generous fillet of silicone sealant after the hub is set over the stub (without PVC cement) -- the fillet
would be between the top edge of the 3" PVC and the ID of the flange hub. I appreciate that silicone
doe not bond well to PVC and wonder if there might be some better material to use for this purpose.

Replys will be very much appreciated.