Can you replace a rotted subfloor from underneath?

Author: Maegan Johnson  |  Last update: Saturday, May 3, 2025

While it may seem tempting to replace the subfloor from underneath if your home has access from the basement to this area, it should always be replaced from the top.

Can you replace a subfloor from underneath?

Welcome to the forums! There is no way to replace the subfloor from below although you might be able to add plywood and 2xs to brace up the existing subfloor. If the hardwood is carefully removed you should be able to put it back down and not have it look like a patch job.

How much does it cost to replace a rotten subfloor?

For an average-sized room of 300 square feet, expect to spend about $900 to $3,000 on the cost to replace subfloors, or $3 to $10 per square foot. Most homeowners spend about an average of $1,560.

Can you partially replace a subfloor?

Replacing subflooring is a relatively complicated task that requires precise measurements. You'll need to make sure all of the parts of your floor are structurally sound. That said, you don't always need to replace the entire subfloor. If only a portion is damaged, you can patch it.

How difficult is it to replace a subfloor?

Replacing a subfloor is not difficult to learn, but it is a labor-intensive and time-consuming job. DIYers who tackle this project on their own should ensure they're comfortable with removing and reinstalling flooring, drywall, and trim before beginning.

How to Repair Bathtub Subfloor Damage Underneath in Basement and Crawlspaces

What is the life expectancy of a subfloor?

How Long Does Subfloor Last? Subfloor typically lasts 30 years or more, but if it is consistently exposed to moisture you may need to replace it sooner.

Does homeowners insurance cover subfloor replacement?

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 to tell if a subfloor is bad?

Sagging or Uneven Floors: A Clear Indicator of Structural Issues
  1. Water damage: Moisture is one of the most common causes of subfloor issues. ...
  2. Inadequate support: If the floor joists are too far apart or not properly supported, the subfloor can start to bow under the weight of the floor covering and furniture.

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.

How do you fix a rotted subfloor with water damage?

How to Fix a Water-Damaged Subfloor: Your 8-Step DIY Guide
  1. Start by Stopping the Water. ...
  2. Expose the Subflooring. ...
  3. Make Your Mark. ...
  4. Carefully Cut Subflooring. ...
  5. Remove Damaged Materials. ...
  6. Speed Up the Drying Process. ...
  7. Reinforce Floor Joists. ...
  8. Install Your New Subflooring.

How long does it take to replace a subfloor?

As previously mentioned, the labor cost for subfloor replacement varies depending on factors like room size and location within the house. Typically, it ranges from $25 to $30 per hour. The project duration usually spans a day or two but can vary based on the extent of repairs and necessary prep work.

Does subfloor rot spread?

Once dry rot occurs, it can quickly spread to nearby wooden structures, causing further damage and increasing your repair costs within a surprisingly short period.

Should I replace an old subfloor?

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 subfloor be screwed or nailed?

Rather than nails, screws are best to use for subfloors — these fasteners are convenient, easy to remove and capable of providing torque that nails lack. Because of their structure, screws can penetrate plywood more easily and improve the connection, whereas nails can weaken the plywood.

Can you replace rotted subfloor from underneath?

While it may seem tempting to replace the subfloor from underneath if your home has access from the basement to this area, it should always be replaced from the top.

Will insurance pay for water damage to a wood floor?

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.

What is the best flooring for bad subfloor?

For very uneven flooring, laminate sheets or tiles may be a better bet. This material is more flexible, but may reveal the imperfections in the surface. The most durable and attractive option for an uneven floor is often a pour on option, such as epoxy.

Does insurance cover floor rot?

Homeowners insurance typically doesn't cover mold or fungal growth. If an increase in humidity slowly causes mold and then wood rot, it wouldn't be covered. As well, if your window seals aren't maintained properly and rain gets in, this wouldn't be covered either.

Can you replace an entire subfloor?

Replacing a subfloor may seem like a daunting task, but with the right tools, materials, and know-how, it's a project that can be tackled by DIY enthusiasts or professionals alike. By following this step-by-step guide, you can ensure that your floors remain strong, stable, and beautiful for years to come.

Which two are not covered by homeowners insurance?

Earthquake, flood, mold, earth movement, and “wear and tear” are some of the perils that are usually excluded.

Why does my subfloor keep rotting?

Sometimes, the source of moisture might not be obvious, such as a leaky pipe, improper plumbing, or water vapor coming up from the ground. Any of these moisture sources can cause subfloor moisture problems.

How much weight can a house subfloor hold?

Safety factor is a measurement with which your floor was designed to support loads without collapsing. Most homes have a safety factor of 40 PSF (pounds per square foot).

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