I removed an old toilet and discovered the flange was set about 1/4" below finished floor. I am guessing it wasn't that way but some time ago may be they re-tiled and now it is recessed.

The flange is cast iron and I guess is leaded into the piping?

In this situation, what is the best way to ensure a leak and trouble free toilet bowl connection?

(1) Use an extra thick wax ring with an embedded horn or use two wax rings to make up the difference.

(2) Use a 1/4" PVC flange spacer that has a two flange bolt slots matching the CI flange, liberally apply silicone or plumbers putty on top of the CI flange, align the two flange holes to match, then use extra long flange bolts to reach under the CI flange slots, then install bowl and wax ring normally.

(3) There are a variety of flange extenders that basically combines a new flange with floor attachments and some sort of gasket seal to the old flange. For example:

(3a) Danco has a "HydroSeat" that looks like this.







(3b) Oatey has a kit with a gasket seal and four different thicknesses that you can choose or combine to get the required height and a fit over flange.



(3c) Danco again has a "Perfect Seal" product that sits on top of an existing flange, has a horn that goes into the existing piping, and a gasket on top that replaces the wax ring. The two holes fit over the existing flange bolts. No drilling holes no wax and allows for toilet base repositioning.







(3d) Other combination of gaskets and flange extender made by Oatey or Sioux Chief.



What is your typical solution to this issue if the subfloor is a concrete slab? Assuming you are not considering removing the old CI flange and relead a new one in at the proper height?



Edited 1 times.

3b or 3d....
the danco is clever but if it is plain steel it will rot.
if the sub floor is concrete and the flange is leaded in cast iron there is nothing to worry about. leaded on flange does not need to be secured to the floor.

Packy is 100% correct. If the Danco flange is not brass or stainless it will rust out and fail. Brass is preferable.

Packy, what I meant was, some of the "extenders" are just spacers, the toilet hold down bolts are still attached to the slot on the CI flange, and the extenders simply add height, therefore you will need extra long bolts. However, some of those extenders are actually new flanges, like the Danco ones, they require new concrete screws to be installed to attach them to the floor, and they fit over the existing flange. The toilet hold down bolts are, if I understand correctly, to be fitted under the new flange, and not the existing CI flange.

This is what I have.



I have no idea if those are stainless. Doesn't look brass to me, if brass I think it needs to be thicker.



Edited 1 times.

sum.....I'd avoid any of those things that have a "horn" on them. Suppose you want to snake that toilet, at a later date. Is there enough good metal left to that existing flange, that you could wire wheel it and get clean metal? I believe spacers are the way to go, but I have doubts about getting them secured to the concrete. I think you'd need clean(solid) surfaces and use silicone or construction adhesive to secure the spacer. An alternative method is to cut that flange off and use a cast iron compression flange, set at the height you need.

sum, you want a set like this...

smear a thin coat of bowl wax on top of the cast iron flange.
put the long brass johni-bolts into the cast slots.
set the flange and smush it down.
note it has a rim on the bottom to extend it down inside the opening on the cast flange.
if it isn't high enough repeat with a second ring.
use an extra nut and tighten the sandwich together.
some of the wax should show on the inside.. wipe it smooth with your finger.
then set the toilet bowl normally.

paul, you still have to secure the compression replacement flange..

packy….those options were only in the event the existing flange was as bad as it looks.

Paul, the flange is actually very solid. It looks bad, and I think there are some corrosion build up, but it's not flaky or yielding in any way. I am not sure I want to use a wire wheel on it though.

Ah ok Packy, I think I follow you now.

By using wax between the flange and spacer, it allows the spacer(s) to be removed in the future.

If I put the johni bolts (is that what these are called?) into the CI flange slots, then lay the spacers down through the bolts, I was wondering how would one remove the bolts in the future since many youtube videos said to use silicone liberally on the spacers. The problem is if it's siliconed in, there is no easy way to wiggle the bolts out of the CI slots anymore since they are going through two small holes on the spacers. With wax then you can just gently pry out the spacers if the bolts are to be replaced.

sum, i use wax between the rings only because i feel it is a tried and true product.
there should be a special place in hell for anyone who uses steel bolts.
solid brass johni-bolts will NEVER need replacement.. EVER..
johni-bolt (to me) is a generic term like 'bandaid..
around here they are called 'closet bolts'.
and 'no' they are not cheap but neither is having to reset a wiggling toilet because the bolts have rotted away.

ditto packy


long bolts from original flange THROUGH the spacers


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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

I have used PVC/ABS compatable cement to make one proper size thick spacer from those type of spacers (Because it's not clear to me what the spacer material is). Apply 100% silicone in /around all bolt holes or possible leaking water path.

ABS can be white



Edited 1 times.

Sum, 1/4" is not that much to make up, I would get the "extra thick" wax ring and call it a day.

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Not a plumber by trade but a fierce DIYer