How Much Does It Cost to Replace Subfloor?

A subfloor ¹ is the base layer beneath your finished flooring (and any underlayment ²) throughout your entire home. It is the part of the floor that you cannot see, attached to the joists, and it is the most important part of your floor since it holds up not only finished flooring, but everything you put in your home, from people to furniture and appliances. Cosmetic finished flooring, or “top flooring” such as carpet, hardwood, tile, or laminate, all sit on top of the subfloor, making it easy to change out your visible floors without changing any infrastructure.

Replacing a subfloor requires all floor layers to be removed first. Since this is the bottom-most layer, it is a labor-intensive job. The average price to replace the subfloor in a 300 square foot room is $1,500-1,650.

Signs That Your Subfloor Needs to Be Replaced

After years of wear and tear, a disaster, or any kind of major trauma to your floors, a subfloor can show signs of damage and need to be replaced. You’ll know your subfloor needs to be replaced when you see certain signs of damage such as uneven flooring, sunken areas, loud squeaky floorboards when you apply pressure, or the floor bouncing or shifting as you walk across it. Other signs of damage include hardwood floors cupping or separating from each other, or linoleum ³, often found in kitchens, bubbling or buckling. Any floors showing weak spots or cracks could have damage on the subfloor.

In a bathroom, a loose toilet or cracked tiles is a sign of subfloor damage. Even a room that smells musty could be trying to tell you that your floor boards need to be replaced. Sometimes the joists also need to be replaced with the floorboards, if the damage extends that far.

A subfloor’s main duty is to add support to the main floor material. When this stops happening due to damage, warping, weakening, or softening, it creates a dangerous living situation.

Causes of Damaged Subfloor

A subfloor needs to be sound and in good shape to hold the weight of everything in your home for a long time. But there are many things that can cause damage to subfloors.

Water damage is one of the biggest disruptors to your subfloor. Water damage occurs if there is a flood, excessive humidity, or leaks in household items like washers, toilets, or sinks. A humid, damp, mildewy basement can also cause damage to the subfloor. When water isn’t cleaned up and dried properly, floor boards can warp and mold or mildew can grow. Both of these issues are dangerous to the people living there.

Leaks in plumbing can either be a large, known leak or a slow, unseen leak that causes damage over time. Both will weaken the subfloor boards and leave room for mold growth and warping. If a heavy item such as a vanity or bathtub sits over this area on the floor it could fall through, leaving you with at least a giant mess, or at the worst a dangerous situation. Make sure to hire the services of a plumber before replacing the subfloor.

On top of water damage and leaks, pests can also cause damage to subfloors. Wood-eating pets such as termites and carpenter ants eat away at the floor leaving holes and soft spots. Powderpost beetles like moist soft wood to bore into. These pets love wood flooring and can cause structural damage to your property.

A crack in the home’s exterior or on the subfloor itself is a sign the floor needs replacing. Cracks weaken the floor and also allow moisture to enter the material. In a new home, settling can also cause damage to a subfloor.

Cost Factors

• Subfloor installations in kitchens or baths may be more expensive due to the items found in these areas. If appliances such as fridges and stoves in kitchens, heavy furniture, or other stand-alone items like a sink or toilet need to be moved or removed, the price of labor might increase. Additional labor costs average between $30 and $100 an hour.
• Contractors will need to remove and dispose of old subfloor materials. They can’t be tossed out into the regular garbage. Sometimes there is a fee for disposal of these materials. Junk removal company charges start at $200 and can run into the thousands, depending on the amount of material being removed. Other times a dumpster is rented. Dumpster prices vary depending on the size of the dumpster and location of the rental. Dumpster rental prices average $500.
• The material affects the price. If adding a moisture barrier or underlayment, this will also increase the time and cost. Brand name versus store name will change the price as well. Flooring materials are sold by the square foot.
• Different homes and different flooring materials require specific thickness or types of subflooring. Some subfloors are concrete only, while others consist of plywood ⁴ or oriented strand board (OSB; more commonly known as particle board ⁵). In mobile homes, for example, OSB isn’t the best choice for a subfloor since the compressed wood chips soak up water more easily than plywood. Mobile homes often don’t have a foundation to protect subfloors from water.
• Subfloor materials cost from $0.60-$7.00 per square foot. The larger the surface area, the more the material will cost.
• In addition to needing to replace the subfloor you may also need to replace floor joists. Joists should be replaced if they also suffer the same damage from things such as wood-eating insects, floods, leaks, or foundation cracking. To repair a single joist costs from $100-$300.

Subfloor Materials

Traditional

Traditional subfloor materials include wood planks, plywood, oriented strand board (OSB) more commonly known as particle board, and concrete slab ⁶. Concrete slabs differ from wood subfloors in that they don’t require joists to hold them up as they are one continuous concrete slab.

Wood planks was the traditional subfloor material used before the mid-twentieth century. They are rarely used in subfloor replacements today. Typically made from softwood such as pine or fir, over time nails loosen and floor boards separate, causing squeaky floors. They are also prone to moisture. Occasionally in a remodel other materials are added on top of the plank to strengthen it without removing it. Wood plank flooring can be repaired with plywood, replaced with plywood or OCB, or have plywood installed on top of it leaving it intact.

New

Today there is advanced subflooring beyond just plywood and OSB. Engineered subflooring materials are created with your environment in mind. Able to withstand moisture, they have their own moisture barriers built in. They also provide insulation, sometimes eliminating the need for underlayment. Engineered subfloors lay on top of concrete slabs rather than directly on joists. They are designed for high moisture areas such as basements. They look like rubber mats on top of OSB boards or rolls.

* We selected a variety of brands to improve and clarify the information contained in this cost guide. We do not receive any monetary compensation from these companies.

Labor

Replacing a subfloor is a labor-intensive job that requires special equipment and training. While you may be able to repair sections of a subfloor yourself, when replacing the entire floor, you should hire a professional. A pro does this every day. They know what to look for with damage, how to prevent damage in the future and the right way to install a sound, solid subfloor that will last the lifetime of your house.

Replacing a small portion of subfloor can be quick and easy for a professional, however replacing an entire floor will take much longer, anywhere from 8-24 hours. In order to replace the subfloor, the finished floor needs to be removed first. If there is an underlayment that will also be removed. Once the subfloor is visible, the professional will pull that up. At this time the joists will also be inspected for damage. If any joists are damaged they will be replaced first. Depending on the material used, the professionals will glue or screw down the new subfloor. They will then place down a new underlayment, if necessary (for example, a carpet pad), or a vapor barrier to prevent moisture, before putting back the old or installing a new floor. If any appliances or furniture needed to be moved before starting the project, the professional will put them back.

Labor costs to replace a subfloor vary between $30 and $100 an hour depending on your location and the difficulty of the job. Floor specialists in major cities tend to cost more than those who operate in rural or suburban areas.

Replace vs. Repair Subfloor

If your subfloor only has minimal damage in one area of the floor, rather than throughout the entire room, you can repair it rather than replace it. This requires only taking up that portion of the floor and laying new subfloor underneath. If the finished floor isn’t damaged you can reuse it. If it was also damaged you can replace finished flooring in that section only.

If the damage to your floor is extensive, such as that caused by flooding in a basement or bathroom, then the entire floor will need to be replaced.

Enhancement and Improvement Costs

Vapor Retarders or Barriers

Vapor retarders or barriers installed over the subfloor reduce moisture and help keep the subfloor safe from leaks and flooding. A vapor barrier costs about $0.50-$1.00 per square foot and is a good investment when replacing your subfloor.

Installing a New Finish Floor

If your subfloor replacement project also involves installing a new finished surface on top, such as carpet, tile, or linoleum the price will increase. Finish floor costs start at less than $1 per square foot for laminate to upwards of $16 for expensive tile. Carpet costs between $7 and $12 per square foot.

Additional Considerations and Costs

• Permits. Permits are not required to replace a floor unless it is dealing with electricity or plumbing.
• DIY. While it might seem like a good idea to do it yourself, installing flooring materials requires following code and, oftentimes, using special equipment. Hiring a professional will ensure one of the most important aspects of your home is replaced correctly and safely.
• Wet Flooring. Wet lumber such as panels and joists, need time to dry before they can be sealed with an underlayment and top floor. If there has been water damage, the joists will need to dry before new subfloor can be laid.
• Acclimating. New flooring materials might need time to acclimate to the environment. Let them sit in the home for a couple of days to get used to the surrounding air which will help prevent any warping or settling after it’s installed.

Remodeling Terms Cheat Sheet

¹ Subfloor: The bottom-most layer of a floor, supported by joists, over which finished flooring material is laid

³ Linoleum: An inexpensive flooring material made from linseed oil, resins, recycled wood flour, cork dust, limestone and mineral pigments, on a canvas or jute backing.

⁴ Plywood: An engineered construction material manufactured from thin slices of wood glued together in alternating grain patterns for strength

⁵ Particle board: An engineered wood product used in construction projects and composed of wood chips, sawmill shavings, and/or sawdust and a suitable binding agent, such as resin.

⁶ Concrete slab: A flat area of concrete that can be used for a variety of purposes, such as a patio or a driveway