Toilet Flange Hole Size

A somewhat strange question about the size of the hole in the sub-floor for the toilet flange...

The toilet drain pipe is roughed in and sticks up through the sub-floor. The pipe is ABS and is 3.5" OD. Months ago, I cut a 4" hole in the new sub-floor for the drain pipe. And finally I'm ready to install the toilet flange.

And now, after thinking installing the toilet flange, I realize that the hole for the drain pipe is probably a bit too small. The ID of the toilet flange will fit over the drain pipe nicely. However the OD of the toilet flange if 4" - exactly the same size as the hole! So...

What is the correct size of the hold in the sub-floor? Is just big enough for the OD of the toilet flange? Much bigger for wiggle room?

I'd appreciate any help.

Thanks,

Dan.

You want the hole big enough to be able to seat the flange to the floor, but not too big so there's something for the screws to hold into. Depends on the brand how small or big the hole needs to be.

Note, the correct location of the flange is on TOP of the FINISHED floor. If tiling, the tile should be under the lip of the flange, which may give you a little leaway. It's easier to notch the tile for the screws before set rather than trying to drill afterwards (possible, but you'll probably need to buy a diamond bit).

The screws should go in and anchor it to the subfloor.

Jim,

Thanks. Great feedback!

Regards,

Dan.