Bathroom floor is soft and spongy underfoot

Find out how far the soft area goes in 10 minutes

1. Walk the floor barefoot and mark every spot that gives. Work from the doorway toward the tub.
2. Press your heel beside the toilet base. A failed toilet seal makes the floor softest in a ring around the flange.
3. Press along the caulk line in front of the tub or shower. A split caulk joint or a leaking pan softens that strip first.
4. Press next to the floor vent and at the metal transition strip. Soft wood there points at damp air under the floor, not a fixture leak.
5. Rock the toilet with both hands. Any movement means the flange, or the wood holding it, has gone.
6. Feel for the firm line down the middle of the room. Firm over the beam and soft between it means the sheathing failed, not the framing.
7. Look from below where you can: crawlspace, basement ceiling, or the belly wrap under a mobile home. Stains, sagging insulation and wet ground name the source.

If one small area is soft and the rest of the floor is firm, a contractor replaces those sheets in a day. If the soft area is spreading, the floor bounces as you walk, or it is soft at the vent and the transition as well, water is coming from below and the whole floor has to be opened.

Repair or replace

What it costs

Runhome contractor estimates for this job, including the trip and assessment.

Can I do it myself?

You can do the finding yourself: press the floor, mark the soft spots, rock the toilet, and look underneath with a flashlight. Cutting is different work. The saw has to stop at the joists, the toilet has to come off and go back on a fresh seal, and wet particleboard tears out in pieces. Hire for this whenever the floor bounces, a joist or beam looks wet or dark, or the work is under a mobile home, because a cut in the wrong place takes the support out from under you. Once you are steering around a spot in your own bathroom, it has stopped being a weekend job.

What a contractor will ask you

Have these ready and you skip the back-and-forth.

• Where it is softest: at the toilet base, in front of the tub or shower, or the same in both.
• When you first felt the give, in weeks, months or years.
• How old the floor is, and when the bathroom was last remodeled.
• Whether there has ever been a leak or overflow from the toilet, tub or shower.
• Whether it feels like a gentle sponge over a wide area or distinct crunchy spots under the vinyl.
• Whether the floor is soft past the transition strip, in the next room.
• Whether anyone has been under the house, or under the mobile home, to look at the floor from below.
• How far the new subfloor should go: under the toilet only, toilet plus shower, or wall to wall.
• A wide photo of the whole floor with the toilet and the tub in frame.

Related questions

Can I just put new vinyl over a soft floor?

No. The covering is not what is soft. New vinyl over wet sheathing telegraphs every dip within months and traps the moisture underneath.

It's been soft for many months or years. Is it still urgent?

Yes. Wood loses strength slowly and then fails at once, usually at the wettest sheet. A floor that has started to feel bouncy is already past the patch-and-wait stage.

The estimate only covers the subfloor. What about what caused it?

A good scope includes finding the moisture source and stopping what is accessible on that visit. Ask for it in writing. A patch under a live leak is wet again inside a year.

What if the beams underneath need replacing too?

That is separate work and a separate price, and no one can quote it from above. Get the underside inspected first, then decide, because framing repair changes the job from flooring to structure.

No known leaks, so why is my floor rotting?

Damp air does it. A wet crawlspace, missing belly wrap under a mobile home, or an unvented bathroom feeds moisture into the sheathing from below for years with nothing ever visibly dripping.