Replacing a Rotted Floor Under the Toilet

Updated: Dec. 13, 2022

For minor rot, a flange support is a quick fix

FH01FEB_REPROT_01-2Family Handyman
Minor wood rot around a toilet flange doesn't always mean you have to replace the subfloor. Solve the problem with a metal flange support instead.

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Install the flange support

Flange support

If you discover minor rot around the toilet flange, install a closet flange support under the flange to transfer the weight of the toilet to solid wood.

If only the area directly below the flange is rotted wood, you can install a two-piece steel closet flange support. It goes under the flange and transfers the load of the flange and toilet (and you) out onto more solid surrounding wood. But if your floor is severely rotted, say more than an inch beyond the flange, you’re stuck replacing the flooring around the toilet.

Flange supports are available at home centers and plumbing supply stores for either cast iron, plastic or brass flanges.

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • 4-in-1 screwdriver
  • Adjustable wrench
  • Corded drill
  • Drill bit set
  • Rags

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.

  • Metal flange support
  • Stainless Steel screws
  • Wax ring