Wobbly Toilet - Not Your Typical Problem

AbSoluTc

I have a toilet that is of course - wobbly. However, it's not caused by the standard problems one might think of. Here is the issue..

The screws holding down the flange are not going through any of the sub floor. They are going through the hardy backer that is on top of the sub floor. The issue appears to be a gap around the toilet hole itself that only has the hardy backer around it. The sub floor falls short. This is an older home and was recently remodeled. There used to be cast iron pipes, now they are pvc.

I have looked it over and will have to remove the toilet and see about screwing it back down correctly. The good news is there is a joist directly to one side so with some long screws, I should be able to get it connected there. However, on the right side, there is at least a 1" gap where the sub floor is not. Is there some sort of device or what not available for an issue like this? Something I can clamp to the underside so when I screw down the flange it has something to grip and attach too?

Thanks!

Mike Swearingen

Can you get to the underside of the toilet in a basement or crawlspace? If so, I would box the closet bend drainpipe with some pressure-treated 2X6s between joists and close to all four sides of the pipe. Then screw long screws through the hardy backer into those 2X6s. That will hold it.
Level the toilet if necessary with beveled plastic shims made for that purpose.
Good Luck!
Mike

AbSoluTc

Yeah, I was thinking of something like that. Sounds like a plan. The cool thing is this toilet sits above the utility closet downstairs - the only unfinished portion of it. Works out great. Now all I need to do is get it fixed.

Should I make the box out of the long side or the short side of the 2x6? I Was thinking of doing it flat, notch out a half circle to get a nice snug fit around the pipe, then glue it in place with liquid nails and finally secure each end to the joist on either side. Screw in angularly. Then I can screw the flange down securely without issue. I have a marble tile floor so I have to be careful with popping the tiles from below when screwing.

Thanks for the info!

spark plug

Speaking (or posting) as a DIY'er. Your TOP priority, indeed should be to have the toilet clamped down properly. Otherwise you will have a "Leaky toilet" issue with the Wax ring. But, after proper clamping, the toilet bowl may still be wobbly, as happened in our case, where a new floor was redone in the bathroom. There was a gap between the NEW floor and the front half of the bowl. The solution was very simple. The gap was filled with plaster (around the front half) and it worked. Proof. After 2 1/2 years it's as steady as ever.!!!(No matter what) Don't Drink and Drive!!!

Mike Swearingen

I personally wouldn't try to screw anything from the bottom up blindly under a marble tile floor. You're asking for possible unnecessary tile damage. Drill pilot holes through the tile in line with the screw holes on the flange from above. Score the small masonry drill bit starting points on the tile with an awl or icepick to help prevent skipping, and then drill just through the tile into the hardbacker.
You can turn the p-t 2X6s anyway that you choose, as long as they are very secured to the floor joists and can hold the toilet down well.
Good Luck!
Mike