View Full Version : Any plumbers advice on best way to replace a rotted toilet floor!

06-02-2005, 09:29 PM
Hi all!

A plea for real world advice from the plumbers perspective:

I finally found (I hope) a plumber who is willing and able to replace a buckled lead soil pipe/brass flange.

Amazingly, I called many plumbers who've never worked on such vintage stuff, seems like the young guys arent learning this and the art is dying. Young plumbers wanted to cut out all the cast iron (in great shape and I like the quiet) and redo the whole DWV setup, when only about a foot of lead pipe is in need of repair.

Anyways--the floor is badly rotted beneath the toilet (but joists are OK) and the plumber I found doesnt work with any carpenters.

No carpenters are interested in this job. It doesnt help that its our only toilet, so coordination is tough and carpenters dont like to have to hurry--unlike plumbers who are used to urgent work.

So--from a *plumbers* perspective, what are some good tips for toilet floor repair?

This is an old house with 3/4 inch diagonal subfloor and 1/2 fir finish flooring. All will be covered with vinyl ultimately. The rotted portion is a 2 feet by two feet.

Preferences for plywood type?

Some people suggest two separate pieces of plywood split down the center of the flange hole (two half moons cut out to make hole then joined at center), others just one piece with a hole.

Some suggest bridging between joists on either side of toilet. Good idea?

What does experience suggest as the best approach to these things?

And finally, any tips on the "only toilet" problem? Is there a ultra deep/forgiving wax ring that can be used to temporaily reset the toilet even if the flange is at an angle (from the buckling) or slightly below repaired floring until the plumber comes to fix the flange/lead soil pipe?

Whew--thats a lot of questions! But I guess the idea is that plumbers no doubt see a lot of floor repairs done *wrong*, so what is the best way to do it *right*?

thanks much for help with a vintage plumbing puzzler!

06-03-2005, 04:23 AM
I am an "old time" plumber but would never repair a lead bend, in fact I have taken out hundreds, but have never installed one. I would replace the lead one with a cast iron bend, repair the floor with two layers of plywood to make the repair even with the existing floor, and then install a new cast iron flange before setting the toilet.

06-04-2005, 06:25 AM
The subfloor under the toilet needs to be strong - the toilet weighs around 60 pounds, and a 200# plus person can be sitting on it, it would have probably another 20-50 pounds of water in it, AND, if it wobbles at all, you'll break the wax seal and it will leak, recreating the original problems.

Your patch needs to at least be big enough to cover two joists - ideally, it would cover more. Most manufacturers of subflooring specify that the minimum length piece should cover three joists (two spaces), otherwise, you are just relying on the nails/screws in the edges to keep it from bowing and coming apart - you really need that joist in the middle to give it some stiffness. Put in a piece and drill/cut a hole for the flange and pipe in the middle. Two halves are the worst thing you can do as there would be no support for that joint. If you put in strong blocking, correctly fitted to the joist bay, you probably could get by with a smaller piece, but more is better. My unprofessional opinion.


06-04-2005, 07:23 AM
Sometimes replaceing a large chunk of subfloor is less work than fitting in a small piece. In any event, it is often convenient to "sister" in some supports parallel to an exisiting joist, with lag screws; or put in some cross-blocking using joist hangers. You want this patch to be solid.