8 DIY Steps to Replace a Subfloor Like a Pro

How Much Does it Cost to Replace a Subfloor?

Your subfloor replacement cost depends on 2 factors — materials and labor. Your material costs won't change substantially whether you hire a contractor or do it yourself — a 32 square foot piece of plywood doesn't change in cost.

Here are the current industry standard material and labor costs to replace and repair your subfloor.

DIY Material Cost to Replace Subfloor

The primary cost to replace your subfloor is the materials. You'll need CDX plywood, which is a coarse pine-based plywood material you purchase in sheets.

The average sheet of CDX plywood is 32 square feet and comes in various thicknesses. A subfloor requires a minimum thickness of 5/8" — subfloor material that's going under ceramic tile or bathroom areas should be at least ¾" thick.

A standard CDX fire-retardant plywood board that's 5/8" thick x 4 foot wide x 8 foot long (5/8"x4'x8') costs $60-70 at most hardware and “big box” home improvement stores.

Past your plywood material costs, you'll pay for screws, construction adhesive and other small parts.

Labor Cost to Replace Plywood Subfloor

The current labor cost to hire a subfloor repair contractor is $45-50 per hour. If you purchase your own CDX plywood sheets, you'll save some money — a flooring company may mark up materials they source themselves.

How Do You Know if Your Subfloor Is Bad?

How can you tell if your subfloor is rotten in the first place? It's not difficult to diagnose subfloor issues — even though it's hidden below your primary flooring, the signs of a damaged subfloor are usually evident.

If you notice any of these 5 things, you likely need some subfloor damage repair:

1. Loud creaking or squeaking from your floorboards.
2. Cracking in your kitchen or bathroom tile, especially around appliances, vanities, tubs and toilets.
3. Cupping in your wood floor.
4. Bubbling in your linoleum tile or laminate flooring.
5. Low or sagging sections of your floor.

There are multiple ways subfloors can sustain damage — foundation settlement, pest and termite damage, and earthquakes, to name a few. But the primary culprit of your subfloor problem is probably water.

How to Tell if Subfloor is Water Damaged 

Most subfloor damage is caused by moisture. If the water damage isn't extensive, you usually don't need a new subfloor — simply replace the small damaged area or hire a floor restoration company to perform rapid structural drying.

If your home is flooded or experienced long periods of moisture from leaky pipes or mold exposure, take immediate action to replace the affected areas of plywood subfloor. Prolonged exposure to that level of moisture causes unhealthy mold levels, structural damage to your floor joist system, and may cause your subfloor to collapse.

There are 3 telltale signs of water damage to your subfloor:

1. A musty smell coming from underneath your floorboards or tile.
2. Leaks in your ceiling — these can be caused by water damage to subflooring on the level above you.
3. Loose kitchen or bathroom floor tile, or shifting grout between tiles.

If you find severe water damage in your subfloor and joist system, shut off your home's water supply immediately and call a flooring expert.

Silver Lining: Most extensive subfloor damage is covered by homeowner's insurance — as long as the reason for your damage is listed within your policy.

How to Replace a Subfloor in 8 DIY Steps

Need to know how to repair a subfloor on your own? If you're handy enough to tackle a small subfloor repair project, these are the 8 steps to a successful DIY project.

1. Know What You’re Looking At

There are 4 layers of home flooring — the floor joist system, subflooring, underlayment, and floor covering.

1. Joists are horizontal pieces of wood that support the structure of your flooring. Think of them as the backbone of your floor.
2. Subflooring is a system of boards (usually plywood) that rests on the joists to create an even plane for your flooring.
3. Underlayment is often placed between subfloors and flooring. It's a layer of thin material — usually fiber, rubber or foam — that absorbs sound, assists in insulation and heat retention, and cushions the ground as you walk.
4. Floor covering is the top surface of your floor that you can see — your hardwood floors, tile, laminate flooring, etc.

2. Check For Potential Risks

Make sure the flooring area you intend to work on is safe. Can the area support your weight and the weight of your equipment? Is there visible water damage? Has your floor covering shifted, cracked or warped significantly?

If you can see signs of damage before you pull up your primary layer of flooring, don't walk on or near that area. Call a licensed flooring expert — your health is worth the extra cost. And if you put a foot through your subfloor, you'll end up spending far more money anyway.

3. Look for Leaks, Then Turn Off Water and Power

If you noticed any water, mold or pooled moisture as you inspected the damaged area, chances are you'll find more after you pull up your floor covering. Stand as far away from the moisture as possible as you proceed.

Once you've established whether there are leaks or not, turn off the water and power supply in your home. There's a good chance your pipes and home electrical wiring run through or near the area you intend to tear up — better to be safe.

4. Gather The Necessary Tools to Remove Your Flooring

You will likely need these 6 tools to remove, pry up or cut into your flooring:

1. Circular saw
2. Reciprocating saw ("Sawzall")
3. Pry bar
4. Crowbar
5. Screwdriver (flat head, Phillips head, or both)
6. Cordless drill

If your tools require an external power source, use a small generator or run an extension cord from another area of your house.  Remember, you want the power cut to that area of your home as you remove the flooring.

5. Pull Up Your Flooring and Underlayment

If you have vinyl tiles, carefully peel them up and set them aside. You need a pry bar for hardwood flooring, laminate flooring or carpet strips. If you're working on the subfloor underneath kitchen or bathroom tile, break and fully remove the tiles and grout.

Avoid extra damage to your floor covering by pulling up 2-3" extra on each side of the damaged subfloor.

Most underlayment materials are easily stripped away with a small knife or razor edge. If you have a double layer of plywood, carefully remove it with a circular saw. 

If your bathroom underlayment contains concrete subfloors, call a professional for assistance.

6. Remove Damaged Subfloor Areas

First, use a stud finder to locate the floor joists adjacent to your subfloor damage. Use them to mark the perimeter of the area to be removed.

Set your circular saw to the appropriate depth — cut just deep enough to break the old subfloor without hitting any pipes, joists or wires. Cut along your perimeter marking around the area of damaged subfloor. 

Use a screwdriver to remove any unnecessary screws, then use a pry bar or crowbar to lift the rotten subfloor area off your joists.

Have a reciprocating saw handy if you need to make any fine cuts between the plywood and your joists. 

7. Check for Damaged Joists — Call a Contractor if You Find Any

We don’t advise repairing or replacing damaged floor joists without a flooring professional. If you notice a broken, rotten or damaged flooring joist, stop work immediately and call a contractor.

Reinforce damaged floorboard joists while you wait for your service appointment. Attach a support joist to each damaged original with a construction-grade adhesive glue. 

8. Install the New Subfloor

If your floor joists are structurally sound, you can install new subfloor in the area. 

The best approach to laying a new subfloor is a tongue-in-groove method. Stagger these connections between sheets of plywood, and aim the edges where boards connect to rest on floor joists. 

Screw the new floor into the joists, then use construction adhesive glue to secure the screws. 

Extra Tips for More Specific Subfloor Projects

If your subfloor replacement project is in your bathroom or under a wall, add the following DIY steps to the list above.

How to Replace Subfloor in a Bathroom — Extra Tips

1. Installing new subfloor material in your bathroom? Use thicker ¾" plywood for your bathroom's entire subfloor to provide greater water protection for your new flooring. 
2. If you're replacing the subfloor in your shower or tub area, add a secondary layer of concrete subfloor. Most contractors use concrete board or pour a “mud floor” (a small concrete slab). Taper the subfloor in this area to gently angle towards your shower drain.
3. If you're replacing a bathroom subfloor near the toilet, carefully cut a circle around the flange with a circular saw. 
4. If your bathroom subfloor damage extends beneath your vanity, cabinets or toilet, pull each of them fully out of the room before you begin repairs.

How to Replace Subfloor Under Wall Areas — Extra Tips

1. Cut away sections of drywall that span over the damaged subfloor. Use your circular saw, set precisely to the thickness of your drywall to avoid cutting wires or pipes.
2. Cut out the damaged subfloor in a rectangular pattern. Cut 1-2" extra on each side of the damaged area to fully remove any mold or moisture damage.
3. Examine your floor joists underneath the wall. If they are waterlogged or damaged, call a flooring expert. Don't risk compromising the structural integrity underneath your wall.

Feel more comfortable hiring a pro to repair subfloor in bathroom areas or under walls? Unless you're an experienced contractor, these probably aren't repairs you're equipped to tackle.

If the damaged subfloor in either of these areas is larger than 5 square feet, hire a subfloor repair contractor.

Need a Pro? How to Hire a Subfloor Repair Contractor Near You

HOMR members asked us 2 questions during our research into subflooring repair. They wanted to know the right type of company to hire for subfloor repairs, and whether a handyman is capable of repairing subfloor.

Do Flooring Companies Replace Subfloor?

If safety and quality matters more than saving a few bucks, a professional flooring company is your best option. A veteran flooring contractor addresses your damaged subflooring, retains the structural integrity of your floor joists, and resets your original finished floor.

HOMR researches, interviews and rates service providers in your area, then obtains free quotes for our members. Our 24/7 home management app is available for just $9/month — never type “subfloor repair contractors near me” into Google again.

Can a Handyman Replace My Subfloor?

It all depends on the individual experience of your handyman. Only hire a handyman with a specific job history of replacing, repairing and installing flooring materials. You'll generally pay less than you would for a flooring expert, but you will sacrifice some quality.

If your handyman doesn't have any experience repairing floors, why not save the money and just do it yourself?