toilet flange question

Hi all, I recently had a slab poured, the concrete ended up quite a bit thicker than anticipated, so the pipe for the toilet is a fair bit too short. I had wrapped it in some foam and tape to keep concrete off the pipe, and then the concrete guys buried it completely, then dug a hole around it with his hands to prevent it from being permanently buried. End result, I will have to lengthen the pipe an appropriate amount and fill in around it to build the surface that the flange will mount to.

So what is the proper way to fix this? I can do what it takes to get the pipe right, but how best to fix the floor? Should I fill the hole with sand up untill there is maybe 3" to go, and mix up a small batch of concrete? Or is there a different matl to use? The tile guys talk about using deck mud for building shower bases, which if I recall is something like 5 parts sand to one part concrete, would that be a way to go? I imagine it would be easier to dig out (than straight concrete) if it ever needed to be repaired/altered, but not sure if it would be strong enough for holding the toilet flange securely. Any hints on fasteners, should I embed some into the wet concrete, or install them after it has cured?

Thanks for the help.


Greg

What you may have to do is cut the pipe a little so you can install a coupling, then a straight piece of pipe to bring it to the proper level. The hard part may be cleaning off the outside of the pipe down in the hole to put on the primer and cement since it needs to be a ways down to allow for the thickness of both the flange and the coupling. They sell an inside cutter for this, and hopefully, you have enough rise to make it all fit...bummer. It would have been easier if the pipe was left a foot or so high, then you could have cut it off later...hindsight is great, isn't it!

The proper way to install a toilet flange is to put it down after the floor is finished. You press it down to the floor and then anchor it through the floor into the subfloor (here it is the slab). I don't think deck mud would hold a fastener very well. Somewhat depends on how big of a depression they left around the pipe, you might be able to anchor into the slab with lead anchors, tapcons, or plastic inserts. If not, then you'd need to fill it up with something sturdy.

Anyways, those are my thoughts...see what else comes up.

i will try to describe this the best i can..

there is a concrete "hole" saw that you can rent at home depot...along with a hammer drill.

if you get say a 5 inch size... you can probably drill down into the concrete around teh pipe creating the clearance to put the flange or to expend the pipe up to the proper level.


i had a concrete slab (4") that i had to drill through and used this tool.

you would be looking at about 70 dollars....

....or you can just chisel around the pipe and do it that way... that's probably just as easy...and cheap.

jadnashua said:

The proper way to install a toilet flange is to put it down after the floor is finished.

Click to expand...

Point of clarification - the concrete is the finished floor. The hole I need to fill should fall within the footprint of the toilet, so I don't need to match the surrounding concrete cosmetically, just in flatness. So nix the deck mud idea, use concrete. Should I cast in some fasteners? If so, what should I use?

I have found that the easiest way to secure anything like this to concrete is to drill a 5/16" hole and insert a lead ferrell. Then a #12 stainless steel sheet metal screw will secure the object. I use a small SDS+ hammer drill to drill the holes. I own my own, but they can be rented very reasonably. I've used this method to secure 2x4 floor sills, furring strips, wall outlets, plumbing hangers, electrical service panels, toilets, and deck canopies. I believe you would want the concrete to be "real" concrete, not mortar as I'm not sure the mortar would have enough holding power. I've tried Tapcon, steel concrete nails, and 22 cal. shooters, and to me this is the easiest and at least as secure as the other methods and better than most.

Once I had determined the proper height of the flange, I'd probably just fill in the area with cement. I suppose you could try casting in fasteners, but I'd probably just drill them after it set. Fresh concrete is still fairly soft - just a carbide bit, not even a hammer drill would be required and still do it fairly fast. The goals are: flange fully supported underneath, proper height, horizontal, and anchored.