Does the subfloor need to be replaced if it gets wet?

Author: Sierra Altenwerth  |  Last update: Thursday, February 19, 2026

A wet subfloor doesn't always need to be replaced, but it must be thoroughly dried and assessed for damage. Use fans and dehumidifiers to dry it out. If the subfloor is swollen, warped, or has mold growth, replacement is necessary.

Is the subfloor ruined if it gets wet?

In most cases, damaged subflooring doesn't need to be replaced. However, in the event of extensive water damage from flooding or extended periods of exposure to moisture, damaged sections may need to be removed to avoid mold and ensure structural integrity.

How do you tell if your subfloor needs to be replaced?

9 Common Signs of Subfloor Damage
  1. Your floor is uneven or sunken-in. ...
  2. Your floorboards squeak — loudly. ...
  3. The room smells musty. ...
  4. Your floors shift or bounce when you walk on them. ...
  5. Your toilet is rocking or loose. ...
  6. Your flooring has cracked. ...
  7. Your hardwood floor is cupping. ...
  8. Your linoleum floor is bubbling up.

Does damaged subfloor need to be replaced?

unless the subfloor has extensive damage or rot there is no reason to replace it unless you need to cut into it to relocate plumbing fixtures etc.

How long does it take for water to damage a subfloor?

If a leak or flood sits on your floor for 24 hours or more and/or reaches the edges of your floor and seeps underneath your flooring, it likely will need to be dried out completely. Usually, this will mean removing the flooring on-top of your subfloor.

Floor Water Damage Repair | Repair or Replace?

Does homeowners insurance cover subfloor water damage?

Homeowners insurance generally covers water damage that's sudden and accidental. For example, if a pipe bursts or a washing machine overflows and damages your floor, you may be covered. But if the water comes from flooding, standard homeowners insurance typically won't cover it.

How to tell if a subfloor has mold?

Subfloor mold often shows up as dark spots or patches under your floors. You might find it under carpets, vinyl, or laminate. The mold can look like black, green, or white marks on plywood or OSB, which are common in homes since the 1950s. A musty smell is a sign of subfloor mold.

How much does it cost to replace a piece of subfloor?

Taking all these factors into account, subfloor material costs can range from as low as $2.50 per square foot for plywood to as high as $10 per square foot for Amdry or Barricade.

How many years does subfloor last?

There are many factors that can affect its longevity, such as the material, the amount of moisture it's exposed to, etc. However, most subfloors can last as long as the home itself. That said, you may have to replace your subflooring after 20 to 30 years if it has absorbed too much water too often.

How to remove a water damaged subfloor?

Remove Damaged Areas

Any area of the subfloor exposed to water damage and rot needs to be removed and replaced. Take a circular saw, set it to one-inch depth, and precisely cut the rotting subfloor areas you marked with chalk. Use a pry bar to remove damaged sections carefully.

How to dry out a wet sub floor?

Fixing a Wet Subfloor in Your Home
  1. Repair the water leak or other moisture problem. ...
  2. Pull up some of the finished floor to test the subfloor's moisture level. ...
  3. Expose the entire affected subfloor as needed. ...
  4. Remove any OSB that is structurally compromised. ...
  5. Dry the damp OSB with commercial fans and dehumidifiers.

Why does my floor feel spongy when I walk on it?

An uneven subfloor is most likely to be the culprit for that spongy feeling if the issue is not evenly distributed but confined to specific areas – particularly if you can rule out causes such as water damage if, for instance, the flooring is newly installed.

Does moldy subfloor need to be replaced?

The moldy subfloor must also be removed and replaced. Particular care must be taken when cutting into moldy wood because the process sends mold spores flying into the air. Moldy wood removed from the subfloor should be enclosed in double plastic bags before it is carried through the house.

What to do if water gets under flooring?

If you have water under your floorboards, remove floor coverings and dispose of damaged paper products, dry the area, clean and disinfect the soaked floorboards, ventilate the room, and contact a professional like ServiceMaster of Lake Shore for complete restoration services.

How do I know if my subfloor is ruined?

When Should You Replace Subfloors? There are many signs that your damaged subfloor should be replaced with a new subfloor. These include squeaks and other noises, cupping or warping, cracked or popped tiles, sagging or unevenness, the smell of mold or mildew, or bubbling tile.

Should I replace wet subfloor?

A wet subfloor doesn't always need to be replaced, but it must be thoroughly dried and assessed for damage. Use fans and dehumidifiers to dry it out. If the subfloor is swollen, warped, or has mold growth, replacement is necessary.

Is my subfloor rotting?

It's difficult to assess if the sub-floor is rotting until carpets or tile are pulled back and an inspection is conducted. However, if the sub-floor feels spongy and sags when walking across the floor, this is a sign of a rotted sub-floor.

Can I replace my subfloor myself?

Over time, due to water damage, pests, or simply wear and tear, subfloors can deteriorate and require replacement. While the task might seem daunting, with the right tools, materials, and know-how, it's a manageable project that can be tackled by DIY enthusiasts or professionals alike.

Does homeowners insurance cover subfloor repair?

Does homeowners insurance cover subfloor? In general, homeowners insurance covers subfloor water damage. However, it must be caused by one of the perils listed in your insurance policy.

How do I know when to replace my subfloor?

Signs Your Subfloor Needs to Be Replaced
  1. There's a Musty Smell. ...
  2. Your Floors Squeak. ...
  3. The Floors Are Uneven. ...
  4. You Can Feel the Floors Move Beneath Your Feet. ...
  5. Your Tile Floor Has Broken Tiles. ...
  6. Your Linoleum Appears to Be Bubbling. ...
  7. Your Wood Floor Is Cupping. ...
  8. The Toilet Is Loose.

Who to hire to replace a subfloor?

Given the complexity of subfloor repairs, you should really stick with a carpenter for this project. But if you want to install a new subfloor or underlayment over sound floor joists, hire a local flooring contractor for this step.

What does water damaged subfloor look like?

The most obvious is a spongy feel or “give” to the affected area. Other signs of water damage include warping in the floorboards of your hardwood floors, loose sections in your tile floor, bubbling or peeling in linoleum, lifting in your laminate flooring, or a musty smell that could indicate mold growth.

Does homeowners insurance cover mold?

Homeowners insurance doesn't usually cover mold damage or removal unless it's the result of a covered peril. If the mold in your residence was caused by something sudden or accidental, such as a bursting pipe or some other covered incident on your policy, you may be protected.

How long does it take for mold to grow on subfloor?

Mold growths, or colonies, can start to grow on a damp surface within 24 to 48 hours. They reproduce by spores - tiny, lightweight “seeds”- that travel through the air. Molds digest organic material, eventually destroying the material they grow on, and then spread to destroy adjacent organic material.

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