How do you fill cracks in plywood subfloor?

When you’re building a new home or renovating an old one, you’ll likely have to deal with the subfloor. This is the layer of plywood that lies below your finished flooring and supports it.

If you have gaps in your plywood, they can cause problems with moisture and structural support, so it’s important to fill them before they become serious issues.

There are several different ways to repair a plywood subfloor: from using wood filler to repairing cracks with caulk or a self-leveling compound.

But how do you know which option is best? In this article, we’ll cover everything from when (and why) you should be filling gaps in the first place all the way through to replacing damaged planks with completely new ones!

Should you fill gaps in plywood subfloor?

If you have a choice, I would recommend using wood filler or caulk. Caulk will fill the crack in your plywood subfloor, but it is not as strong as wood filler. Wood putty works well for filling cracks in plywood subfloors, however, it can sometimes be difficult to apply evenly.

A self-leveling compound can be used to fill gaps in plywood subfloors; however, this product may cause more problems than it solves because when you paint over a self-leveling compound (or any other sealant), it may bleed through and leave an uneven finish on your flooring material.

Polyurethane is another great option for filling gaps between sheets of plywood; however, like other sealants used on floors, polyurethane can also bleed through when painted over creating an uneven surface on your flooring material.

How do you fix gaps in plywood?

If your subfloor has gaps, you can fill them with wood filler.

Wood filler is a paste that’s made from sawdust and glue, so it will dry hard and smooth. When you spread the wood filler over a crack or hole in your plywood flooring, it will look like just another piece of solid plywood when it dries.

Wood putty is similar to wood filler but comes in different colors so you can match the color of your flooring if necessary.

Wood putty also hardens more quickly than wood filler does, which means you won’t have to wait as long for it to dry before walking on top of it again.

If neither of these products sounds like what you need for filling cracks in plywood subfloors then patching holes with carpentry tools might be better suited for your job instead!

How do you repair a plywood subfloor?

How do you repair a plywood subfloor?

Supplies: wood filler, putty knife, wood glue, sawdust, and sandpaper.

Step 1: Fill the cracks with wood filler. Use a putty knife to apply wood filler to the cracks in your plywood flooring. Apply pressure to spread out the fill while it sets up.

Step 2: Apply glue to the seam where two pieces of plywood meet and clamp them together until they are set up completely (about 30 minutes). Sand down any rough spots on your seams before moving on!

How do you fill gaps in a subfloor plank?

  • If a gap in a floorboard is small and the nails are still intact, you can fill it with wood filler.
  • Apply the putty to the crack, then smooth it down with your finger or a putty knife so that there are no bumps in it (the surface should be completely level).
  • Use fine sandpaper to remove any excess filler before sealing it with paint or varnish.

How do you repair a cracked subfloor?

  • Tap out the bad piece. If you have a hammer and the bad piece is large enough, it’s easy to tap out the old subfloor with a few quick whacks. Take care not to damage your subfloor while tapping out the old flooring.
  • Use a chisel to remove the bad piece. If you don’t have access to a hammer or if your subfloor is too thin for tapping, consider using a chisel instead of trying to hammer on it yourself. Be careful not to damage any surrounding drywall when using this method!
  • Pry out the bad piece with a screwdriver if all else fails — but only as an absolute last resort! This can be done by placing one side of your screwdriver under one end of broken plywood, then prying upward against two adjacent pieces until they pop up slightly from their nail holes in order for you to get enough leverage for removal (or just use two different-sized flathead screwdrivers).

Can you use self leveling compound on wood subfloor?

If you’re not looking to do any major remodeling, you can fill small cracks and dents in your plywood subfloor with a wood filler or putty. Once dry, sand the surface smoothly and then apply a coat of primer to give it a good base for paint.

If there are larger holes or gaps in your plywood subfloor, consider using a self-leveling compound instead. The compound is applied in layers and will create an even surface once cured.

This method also works well for filling nail holes, but if you’re doing this job yourself I recommend getting an electric drill with a brad-point bit attachment and just driving all those nails back into place!

Is it better to use wood filler or caulk?

Fillers are better for filling gaps and cracks, while caulks are better for sealing them. Fillers can be sanded and painted, but caulk cannot be.

Caulks tend to have a flexible consistency that allows them to expand and contract with changes in humidity levels, making them ideal for sealing large gaps between surfaces like floors and walls.

They don’t require any kind of reinforcement under them because they’re not structurally important; most people use wood filler on subfloors instead of caulk because their primary purpose is to blend the floor back into its surroundings, not hold up the house!

Can you use wood filler on plywood?

Wood filler can be used on plywood. It can also be used on hardwood floors, laminate flooring, engineered wood flooring, and concrete floors. In addition to all of these surfaces, it can also be used on ceramic tile floors!


It is important to know how to fill gaps in your plywood subfloor. It will help you to maintain the structural integrity of your home or office and keep things from getting worse.

You can also use this information if you want to repair or replace damaged wood floors.

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Martin Flood

Martin Flood has been working in the construction industry for over 20 years as a general contractor with expertise in remodeling projects that are large or small. He has furthered his career by specializing in epoxy resin flooring, providing excellent service to both commercial and residential clients. Martin’s experience enables him to offer professional advice on how to choose the right type of project based on your needs and budget.

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