Toilet flange above or level with floor

[dmaceld]

I find several comments in this forum where the authors say a toilet flange should be on top of the finished floor. There are also a couple of posts where in that case the poster had problems with rocking toilets due to insufficient space between the flange and toilet bottom. I have a copy of Code Check Complete which is a summary of four primary building codes. In there the authors have an illustration specifically showing the flange top level with the finished floor as being the correct installation and a big NO circle over the illustrations showing the flange on top of the finished floor and below the finished floor.

What I find of the plumbing codes the only code requirement is for the flange to securely fastened to surface below it.

Soooooo, what is the correct positioning of the flange to avoid clearance problems and still have a water tight seal?

[SewerRatz]

Only part in Illinois plumbing code is as follows.

Section 890.360 Water Closet and Pedestal Urinal

Fixture connections between drainage pipes and water closets, floor outlet service sinks and pedestal urinals, and earthenware trap standards shall be made by means of brass, copper, hard lead, plastic, or iron flanges; caulked, soldered, screwed or solvent welded to the drainage pipe. Flanges of hard lead, plastic and iron flanges for no-hub or compression joints shall be secured to the floor. The connection shall be bolted, with a gasket, washer or setting compound, between the earthenware and the flange. The floor flange shall be set on an approved firm base. The use of putty or non-drying plumber's putty manufactured specifically for plumbing installation is acceptable

It does say it needs to be set on an approved firm base. I always put it on the sub-floor, and let the tile guys tile around it. So I make sure it will be installed flush with the finished floor.

[kingsotall]

I always put it on the sub-floor, and let the tile guys tile around it. So I make sure it will be installed flush with the finished floor.

OK, here goes...
WE SET THE FLANGE FLUSH WITH THE FLOOR TOO!

[Cass]

Always on the finished floor for proper tolerances between toilet and flange so the wax ring can do it's job to the best of its ability.

[SewerRatz]

Always on the finished floor for proper tolerances between toilet and flange so the wax ring can do it's job to the best of its ability.

I do not use wax, I use the Zurn Neo seal or plumbers putty.

[McMike]

the last company i worked for(service plumbing and remodels) had a policy of flange on finished floor, the majority of the leaky toilet floor seals we were called to repair were 3inch pvc flange 10-15 years old, below floor level, if we used thicker wax we would still have problems within our 2 year warranty, so the company requires flange to be cut out and repiped to sit on FF, those flanges that were reset on FF would easily last well past our 2 year warranty, it was very rare to see a leaky floor seal with a flange set on FF

[shacko]

I do not use wax, I use the Zurn Neo seal or plumbers putty.

If I remember putty was banned on toilets over forty years ago!!

[jadnashua]

There are two issues...the flange must be firmly attached, and, it is designed to sit OVER the finished floor and anchor through it. If the flange is installed tight to the floor surface AND that surface is flat and level AND the flange is not poorly designed AND the toilet is standard with decent quality control, you should be able to use a standard wax ring and get a reliable, waterproof, gasproof seal. A thick wax ring filling a wide space isn't as reliable (but could last a very long time if not disturbed) as a thinner one. Since a typical flange ring is only in the order of approximately 1/4" or so, if it was ultimately level with the finished floor, would having the wax an extra 1/4" be a major factor? Maybe if you got really aggressive with a plunger, but probably not.

Issues with a toilet not fitting are usually related to a flange that is not sitting ON the finished floor and is sitting above it, or not level with the floor. Also, some people think the use of a horn embedded in the wax ring is a good idea...the higher the flange is, especially on a 3" drain pipe, the more problems you'll have since that horn does have some uncompressable thickness and width and may not fit into the throat of the flange.

Essentially, any properly made toilet should fit on any code approved flange IF the flange is installed on TOP of the finished floor properly. There are a lot of junk toilets out there that may not meet industry standards.