What Is the Process for Repairing Water-Damaged Subfloors?

Once the area is dry, the next step is to remove the finished flooring above the subfloor. This includes carpet, tile, hardwood, or laminate, along with any underlayment or padding. Damaged materials may be unsalvageable, so they need to be taken out to expose the subfloor beneath.

The pros will assess how far the water spread and remove flooring in a large enough area to allow proper inspection. They may also check for water that traveled along walls or into joists. Removing more than the visibly damaged area is often necessary to ensure a clean repair.

• Turn off the water supply at the main shutoff valve to stop active leaks
• Use a wet vacuum to extract standing water from the subfloor surface
• Run fans and dehumidifiers to speed up drying, especially in humid weather
• Remove carpet, tile, or hardwood to expose the subfloor for inspection
• Check for water wicking up walls or into floor joists beyond the visible wet spot

If the subfloor is damaged beyond repair, the pros cut out the affected sections and replace them with new plywood or OSB. They match the thickness to the existing subfloor to keep the surface level. Screws or nails secure the new panels to the joists.

For minor damage, they may reinforce the area with additional blocking or sister the joists. The goal is a stable, even surface that can support new flooring. After replacement, the pros sand or level the surface to remove any height differences between old and new sections.

• Cut out only the damaged subfloor sections, leaving sound wood intact
• Use new plywood or OSB that matches the existing subfloor thickness
• Secure new panels with screws or nails made for subfloor use
• Reinforce weakened joists with sister joists or blocking if needed
• Level the surface with a self-leveling compound if there are low spots