Toilet Installation - New Construction

[Tom Sawyer]

I'm still confused about this issue. I've heard from a plumber and read from other sources that the flange should not be lower than the finished floor because then the toilet edge would prevent the horn from being able to seal properly. This makes logical sense to me given the design. However, jadnashua, you make a valid point about the issue of rocking. I also wandered just how much you can compress the wax seal and still have adequate coverage. Therefore I'm still trying to figure out what the parameters are. I've read in tile books that the flange can be from 1/4" - 3/8" higher than the finished floor. But I'd like to hear more from the experts in the field.

I'm thinking of measuring my toilet (a Toto Drake) to see just how much space there is between the horn and the edge of the toilet, but I still need to have some idea of how much compression the wax seal can withstand.

So, for a proper installation make sure the flange sits right on the finished floor and is secured with rust proof screws.

The flange should sit above the finished floor. Toilets are designed to have the flange sit above the floor. Below the floor will not compress the wax properly and many times shims or stacked wax is the only way to make a seal.

 

[Jadnashua]

Note, the horn is sized to normally fit inside the toilet flange when the flange is properly located. With the addition of the wax, your outlet is below the rim of the flange (essentially at finished floor level), and the wax acts as the overflow and gas seal. If the flange is too low, the wax acts as both the waste and gas seal.