I'm replacing a toilet and am using a Hydroseat rather than replacing the damaged flange. The problem that I've run into is one of the spots to anchor the Hydroseat down seems to be hollow below the tile.

The other three spots hit the concrete slab and I've anchored to them successfully, but I'm not quite sure what to do about the one sitting above the void. I'm not sure how to anchor it to the floor without hitting concrete or wood. Any ideas?

1 Answer 1


you can just inject hydraulic cement into the void and let cure. then anchor your flange with a tapcon type screw. or just inject the hydraulic cement and then insert a screw into the wet cement. when it cures, it will lock the screw in place.

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