What do I do in situation as on the scheme below?
As you can see flange bolts are just hanging in space.
Do I fill space between cement floor and pipe with new cement and then screw bolts to it?
Other options?

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1 Answer 1


In the situation where a toilet flange is in the drain pipe through a concrete floor, there does not have to be any bolts holding the flange down.

The pipe will be held tight in the concrete and the flange glued to that.

For your particular situation, I would fill in the gaps with a little cement or even thin set. No bolts are needed except those to hold the toilet. Keep the cement out of those slots.

  • I think it depends on your flange. Some are very secure, others not so. But I'm with RMDman—fill in the space and fasten your flange down. What you fill with depends on how big the void is.
    – Huesmann
    Mar 12 at 14:04

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