I'm getting ready to install a toilet flange in my unfinished bathroom (in the basement so the flooring is a concrete slab and will eventually be ceramic tile). There is currently a 4" stub out sticking up out of the slab for the toilet drain. I thought I could simply cut the pipe down closer to the slab and glue a flange to the inside of the pipe but a friend recently told me I would have to chip the concrete around the drain pipe away in order to install the flange (meaning the flange would be secured to the outside of the pipe). Is that correct? My next door neighbor just installed a toilet (with the same set up I have) and he didn't chip away the concrete floor around the drain pipe for the flange installation. Thanks in advance!

I'm getting ready to install a toilet flange in my unfinished bathroom (in the basement so the flooring is a concrete slab and will eventually be ceramic tile). There is currently a 4" stub out sticking up out of the slab for the toilet drain. I thought I could simply cut the pipe down closer to the slab and glue a flange to the inside of the pipe but a friend recently told me I would have to chip the concrete around the drain pipe away in order to install the flange (meaning the flange would be secured to the outside of the pipe). Is that correct? My next door neighbor just installed a toilet (with the same set up I have) and he didn't chip away the concrete floor around the drain pipe for the flange installation. Thanks in advance!
They make both inside and outside flanges. If there's no space around the stub up then you will have to install a inside flange. No need to chip the cement away. Good luck, Tom

There is space to chip away around the pipe if that's what I need to do (although I'd rather not if I don't have to). I guess what I'm asking is, is one method better than the other, i.e. inside flange vs outside flange? Thanks!

There is space to chip away around the pipe if that's what I need to do (although I'd rather not if I don't have to). I guess what I'm asking is, is one method better than the other, ie inside flange vs outside flange? Thanks!

No need to go through the hassle of chipping out the cement to install a outside flange. Save yourself some work and install the inside one. Cut the stubout as close to the floor line as you can, ( not even a little peeking out) as anything that's left above the floor line will make the flange not set directly on the floor and the toilet will have to be shimmed or it will rock. Good luck, Tom

One more question on this topic... as mentioned before, the toilet flange I am getting ready to install is in the basement, i.e. on a concrete slab. Obviously, I will glue the flange to the existing drain stub out but I believe I also anchor the flange to the slab, correct? If yes, what kind of nails would I use to do this, regular masonry nails? Or some sort of anchor/screw? Thanks!

One more question on this topic...as mentioned before, the toilet flange I am getting ready to install is in the basement, ie on a concrete slab. Obviously, I will glue the flange to the existing drain stub out but I believe I also anchor the flange to the slab, correct? If yes, what kind of nails would I use to do this, regular masonry nails? Or some sort of anchor/screw? Thanks!


You shouldn't have to nail the flange down. After the glue sets up, try to lift it up. If it won't budge you're OK. However if it gives we secure the flange to a cement floor with cement screws,(Tapcons). Good luck, Tom

This helps me too thanks