How to Install Hardwood Floors on Uneven Subfloor or Concrete | Full Guide

How to Install Hardwood Floors on Uneven SubfloorHardwood floor installation is a pretty good move since it’s one of the best long-term possessions you can have for your house. But the installation process is going to be a bit of a ride that involves both ups and downs. Today we are going to cover how to install hardwood floors on uneven subfloors.

Throughout the installation process, you will encounter a few unknown situations and might need help sorting through the problems. One such situation is having uneven subfloors that are quite inappropriate for hardwood floor installation.

Often if not always, you’ll find the floor installers using the word “level” a lot when it comes to installing hardwood floors. However, what they truly mean is the word “flat”. Surely everybody wants to have a level floor in their house. But that is not the case with most households.

And so, you surely do need to work on laying wood floor over uneven subfloor by making it even first. Let’s talk about the complete process for how to install hardwood floors on uneven subfloors or concrete.

Installing Hardwood Floor Over Uneven Subfloor

The first thing we need to work on is making the subfloor even. Installing wood flooring over an uneven subfloor will make the floor less faltering and even. So, by using some self-leveling compound, you’ll need to even the subfloor first. These compounds are safe to use for installing hardwood floors on concrete subfloors too as long as it’s strong enough to support the weight.

Materials & Tools Required:

  • Self-leveling compound
  • latex paint primer
  • adhesive, seam or duct tape
  • notched trowel,
  • paint roller, wet sponge
  • trowel, sandpaper, sand, saw
  • 2-by-4-foot wood pieces
  • hardwood floorboards, and some heavy items

Subfloor Leveling Process

Bring the 2-by-4-foot wood pieces and cut them down to fit in the room’s doorways. Use the duct tape for holding it in place. This will help the self-leveling compound. As a result, there will be no leaking into rooms. Leveling subfloor for hardwood flooring will also need to clean it with a wet sponge. Let it dry completely so that the compound can stick better with the subfloor.

Now use seam tape or duct tape for covering the seams. These are noticeable between the floor and walls. There could be holes that can let pipes go pass through the floor, you need to seal those with seam tape as well. So that the self-leveling compound is impossible to spread.

Time to use some latex paint primer for painting the floor. Let this dry for some hours to make the compound stick better later on. Use a trowel to nicely spread the poured self-leveling compound on the floor. It should start settling inside the alleys of the subfloor. And this should start making the subfloor look even. In case the compound leaks out from the wood barrier, use some sand to absorb it.

You need to allow the self-leveling compound to dry for half a day at least. Use medium grade sandpaper for sanding down the ridges.

Installation Process

Having the right floor adhesive as well as a self-leveling compound is very important. So, don’t compromise the quality to save some money while making these purchases. Start by applying the floor adhesive and spreading it on a section at a time. You should begin from the wall near the floor section. Use a notched trowel for spreading. The trowel’s notch will help to create groves while spreading.

Now place the first board on top of it. Make sure the groove side is facing the wall while placing it. Then move to the section right next to what you just finished. And apply the wood glue on groove part of piece you need to stick next. Now fit it with the first board’s tongue and press nicely.

Using this manner, add all the remaining floorboards until the entire floor is covered well. Finally, you want to place a heavy item like a concrete block over the flooring. So that it can press the adhesive nicely while drying. Let it dry completely for the required time that should be mentioned in the manufacturer’s instruction.

And then move forward for sanding the surface to get all unevenness out of sight. But just prior to that, use some wood floor filler to work into all the gaps that might be visible between boards. Let the filler dry for at least that night.

Then using a drum sander and suitable sandpaper, you need to level the surface. Focus on the edges too since people often miss those areas. Once you are done sanding, use a vacuum to get rid of any excess remaining. You can also wipe it with some clean water and a cloth for an even better result.

After that you can go ahead for applying a preferable stain that can also protects the flooring from certain elements. You can also use polyurethane finish as it works best for keeping the hardwood floor away from damaging any time sooner.

Very soon, we’ll be covering the whole sanding and finishing process in detail for a future article, so look forward to it.

You may read: How to apply oil based polyurethane to wood floors

Gluing VS Nailing Hardwood Floors: Which is Best?

To fix the solid hardwood floor, there are basically two ways you can apply. One is gluing and another is nailing it down to the subfloor. One more way is going for a hardwood flooring underlay through floating. Which one has a better result? Well, depending on a few matters, both can be better on certain occasions.

Now depending on your subfloor, either gluing or nailing might be the best for you. In the case of a chipboard or concrete subfloor, glue works better. While in the case of a wooden subfloor, the nailing method brings a good outcome. Also, if you are willing to fit the hardwood floor to joists, then using secret nails to place will be a wise choice.

You may read: Is underlayment necessary for hardwood floors

How Long Does It Take to Install Hardwood Flooring?

The answer once again depends on a few factors. On average the required time is between 1 to 3 days. If you work along with a partner, then it should take a day for laying 750 to 1000 square feet of flooring. A space that is wide open and less messy will take even lesser time. 

How Much Does It Cost to Install 1000 Square Feet of Hardwood Floors?

The average cost to install hardwood flooring is around 7500 dollars. While if we talk about a range, because there can be many factors that can make you spend less or more than average, then it’s going to be somewhere between 6000 to 11000 dollars for every thousand square feet. This will depend on the type of hardwood you choose.


And that was all about how to install hardwood floors on uneven subfloors. When you try to fix an uneven subfloor, there are a lot of other things you’ll need to pay attention to. The effort you put into leveling the subfloor will show once you’re done with the overall hardwood flooring installation.

The look of a beautiful floor that has no visible crack or break, will surely make up for all the hard work you put into leveling out the subfloor. So, keep in mind this piece of motivation when you feel like giving up on the project. Good Luck!

You may read: How to install Laminate Flooring

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