View Full Version : No support under toilet flange

Alan Bechard
03-25-2007, 07:27 PM
Hi folks, just got steered over to this site, and wish I had read a bit more sooner..............:o

Remodeling a 40 year old home. Has 4" Cast iron pipe under the toilet. Rotted plywood floors in bathroom.

Pulled out all floors, and subfloors, put in 3/4" Ply subfloor glued and screwed down, then 1/2" Hardy board, then tile.

Left the bell end of the cast iron pipe in place while deciding what to do and cut the floor back around it to place it over it for install.

The CI bell was too high (about 1/2") above finish floor level, so decided to cut it off, install new 3" PVC with soft adapter coupling with the 3" PVC sticking down into the CI 4" pipe. Did not know at the time about the Oatey or push fit flanges,,, Dooohhhhh.

So, went to install my toilet flange today, a Chief with stainless outer ring, and realized I have cut my subfloor out too far to get it over the bell. The outer edge of my ring is on the tile, but there is no support directly under the ring.

I know the "right" answer is to remove it all, and properly size my subfloor hole, but with all the glue and screw's and tile there, that will be a REAL challenge.

I am considering removing some tile and subfloor say a 2" radius bigger yet, going underneath the floor (basement home) and doing a tight fit of 3/4" plywood from underneath, then bond down a "donut" of tight fitting 3/4" ply then a slightly bigger donut of hardy board, then retiling up to the drain pipe then setting in the closet flange and securing it too my "donut" as well as through to the underlying plywood.

Man have I made a mess of something that should have been easy, just did it all in the wrong order, and seemed to learn my lessons directly After doing something that was difficult to reverse.

Anyone have some ideas? Does my plan sound reasonable, or am I creating another mess?


I did search and spent the last hour or two reading lots of various posts that seemed to skirt this subject but wanted to ask direct on my situation.

Thanks again.

03-26-2007, 07:05 AM
Proposed Summary:
1. flange rests firmly on tiles? Tile is strong enough to hold flange.
2. toilet rests firmly on tiles?

Toilet rests on its perimeter, not on the flange. Wax makes up the difference in space there. Weight of toilet does not stress flange or pipe.

Action to take:
1. post picture of flange in hole. Where do bolts go?
2. wait for someone else, who has set a lot of toilets, to come in and comment.


Gary Swart
03-26-2007, 08:56 AM
"I know the "right" answer is to remove it all, and properly size my subfloor hole."

Don't feel too bad, we all hope there is an easy solution to problems even when we know deep down we're screwed. One of the prices we DIYer pay is sometimes having to redo things that a pro would have done right the first time. It rarely pays to cut corners. You end up with a half-assed job that won't hold up and often looks like crap too.

03-26-2007, 10:29 AM
I personally wouldn't care what it looks like from underneath. If you get a good seal from the wax ring and the toilet is stable (not rocking at all) then you have succeeded. If not, you'll have to make a new plan.

Alan Bechard
03-26-2007, 07:43 PM
Well, looked at it again with my bud, and decided it was not that bad. Went with the glue and screw and lay in a new section from underneath. The toilet will carry the weight on the tile floor, and the flange is supported around the outer edge, and the closet bolts will be pulling it upwards.

Done deal, here are the two pics before from the top, and after from the bottom.

Ooops sorry, have to resize. Project for tomorrow I guess :o

Got to get the DW to do that for me.

03-28-2007, 06:14 PM
If you have any doubts, there's a two part metal repair plate, sold at Lowes/HD, intended for dealing with rotted floors or holes cut too big, that sits within the toilet footprint and supports the flange.