How To Fix A Toilet – Cement Sub-Flooring Repairs – Part 1 Of 2

This is video #1 of a 2-part series. The videos are:

Part 1 =
Part 2 =
Flange Part Overview =

To watch the Flange Cement Slab Playlist =

Flange Install on Cement Floor

Some toilets are installed and mounted directly over cement slabs. This type of installation is usually found on the 1st floor of a house. During the original construction, ABS glue is applied to the toilet flange, which, on cement slabs, is usually a 4-inch female flange, and the toilet flange is inserted into the sewer inlet. Pilot holes are then drilled into the cement, and then cement screws are installed, securing the flange to the cement slab. Next, hard flooring is installed to the base of the sewer line, or carpet to the base of the toilet. The wax ring is then placed and the toilet is mounted over the flange.

The toilet flange and wax ring will endure for many years under perfect conditions; however, water is often exposed to this area. This exposure will not affect the cement slab and toilet base, but a metal flange securing the toilet to the cement floor will corrode and fall apart if the exposure is prolonged. Once the toilet flange falls apart the toilet will become unstable and begin to move, causing the toilet to leak water at its base.

There are two ways this problem can be corrected. The first way is by installing a replacement ring over the top of the existing flange. This can be a useful fix in situations where the flange’s mounting guides are broken or its cement holes are stripped, requiring new holes to be drilled. The repair ring should not be used however, if the flange is corroded or rusted out, as a repair ring placed on top of a rusted flange will only become rusted itself.

The second way to fix this problem is to cut out the damaged flange’s metal ring, leaving the ABS coupling, and install an inside fitting flange. The reason that this technique is suggested, rather than removing the entire old outside female flange, is because the fit between the cement and the sewer inlet can be so tight that cement would need to be chipped away in order to rid the sewer inlet of the old flange’s outside ABS coupling. This is possible, however, not highly recommended, as new cement would have to be patched in. Furthermore, in most situations an inside fitting flange can be quickly and effectively installed, and easily removed and replaced in the future.

Flange Inspection

To establish which of these techniques to use, the toilet needs to be removed, and the wax ring needs to be cleaned, so that the flange can be inspected closely. The flange should be free of any type of rust or corrosion and the mounting channels should not be bent outward or appear to be broken. The flange itself should be securely mounted to the cement slab.

Parts Needed

The parts needed for this repair are a new flange or flange repair ring, depending on the technique that will be used; cement screws, to secure the flange or ring to the cement slab; ABS glue, to seal the flange to the sewer inlet; and a new wax ring and toilet mounting bolts.

Tools Needed

The tools needed to perform this repair are: an electric drill to drill starter holes and screw in the cement screws; a cement drill bit that fits the size of the cement screws; a wire brush to clean the old flange if necessary; a flathead screwdriver and possibly a mini hacksaw.

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