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Anchoring of Toilet Flange

Richard replaced a cast iron toilet flange and spacers to stop a leaking problem this past weekend.
He used small wood blocks to build up the sub-floor and a replacement PVC flange with an adjustable gasket to seal on the inside of the old cast iron pipe.

Why did he not anchor the replacement flange to the floor?

All the stresses on the flange are transmitted to the gasket. If the flange were anchored to the floor the movement of the toilet bowl would not affect the gasket.

Re: Anchoring of Toilet Flange

I don't watch the TV show and can't speak to the specific installation. He may have said the words "attach this to the subfloor later" but not done the activity.

We secure ALL our tub flanges to the subfloor for a very good reason - aggressive toilet use puts the opposite force on the flange, trying to lift / pry it off the floor. The stainless steel flanges are our first choice if Cast Iron isn't in place already.

Re: Anchoring of Toilet Flange

I saw that and think he wanted the flange to be at a level that was as if it was on the finished floor, not the sub floor. Keep in mind that was a special adapter and not a regular flange.

Re: Anchoring of Toilet Flange

I did not see that show, but I guess he used a 'push in repair flange', the type that is inserted into the cast iron drain. This type of flange is not secured to the sub floor.

These flanges are useful in older homes, where the cast iron drains are old and brittle.

Re: Anchoring of Toilet Flange

Never install a toilet on a flange that isn't fastened to the floor. In many cases you will be pulling the plumbing up instead of pulling the toilet down.

Re: Anchoring of Toilet Flange

My recall isn't the best these days but I seem to remember seeing him help a HO on the "Ask" segment who was going to tile the floor later, and this was why there was no attachment made here. But the other's are right- the flange must be secured to the floor system and you can't do this too well. This is an area where I use stainless steel hardware, as sewage leaks will rapidly corrode any other common screw material. I still have a small stock of #12 1-1/4" stainless wood screws left over from my commercial door hanging days as almost all of those were metal frames. They do a great job here so long as the wood is OK.


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