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Can You Lay Hardwood Floor Over OSB?

Oriented strand board (OSB) is a great material for a range of applications, however, I was wondering whether you can lay hardwood floor over it. I did some research and here’s what I found.

Laying hardwood floor over OSB is feasible, provided the OSB is in good condition, level, and properly secured to the floor joists. Before installation, ensure the OSB is free from damage, moisture, and is of an adequate thickness to support the hardwood, typically at least 3/4 inch.

OSB and hardware tools

However, moisture is a notorious adversary in this scenario. Like a sponge absorbing water, OSB can swell and warp when exposed to moisture, which in turn can cause hardwood floors to buckle or gap. To mitigate this, it’s critical to ensure the OSB subfloor is thoroughly dry and to consider applying a moisture barrier between the OSB and the hardwood flooring. This preemptive strike against moisture will safeguard the integrity of your hardwood floors, much like an umbrella shielding you from an unexpected downpour.

Another key factor to consider is the flatness of the OSB surface. Any undulations or roughness in the OSB can translate to creaks and unevenness in the finished hardwood floor, much like how a bumpy road can make for an uncomfortable car ride. Sanding down high spots and filling in low spots on the OSB to achieve a uniformly flat surface is essential before laying down hardwood floors. This preparation ensures a solid foundation, promoting a smoother installation process and a beautifully finished floor that feels as good as it looks.

Whether you’re interested in how to lay hardwood over OSB correctly, whether you can lay engineered hardwood over OSB, and whether you should, this article will explain everything you need to know about how to lay hardwood floor over OSB.

Should You Put Hardwood Over OSB?

Contractor standing in front of OSB

Although hardwood looks amazing, and OSB is definitely a good option. Is it a good idea to lay hardwood over OSB? Here’s what you need to know:

As a general rule the major factors that you want the underlayment – the material between the subfloor and the surface – needs to absorb moisture, sound, and provide some cushion. OSB is great for sound, and cushioning. But, it isn’t the best at handling moisture. And there are better options.

When OSB gets wet, and then dries it can soften the OSB much more than a similar piece of plywood. Also, synthetic underlayments like foam are a better option because they provide all the benefits of a softwood like cork, plywood, or OSB.

But, none of the drawbacks such as expanding, and weakening with moisture. OSB will work, however, and will work exceptionally well if it never comes in contact with water.

However, in most floors condensation will always form between the subfloor and the underlayment. And so keeping your OSB mostly dry is virtually impossible. For that reason, it shouldn’t be your first option.

Can You Lay Engineered Hardwood Over OSB?

Tools lying on top of OSB

Each type of wood has its own unique characteristics and engineered hardwood is no different. So, can you lay engineered hardwood over OSB?

On average engineered hardwood can be laid over OSB, but it’s NOT the best option for the underlayment. OSB, unlike other options, is prone to expanding when it comes in contact with water, and then never shrinks back to its original shape.

You won’t generally notice any expansion in your OSB when you use it as an underlayment because it’s all covered. But, around the edges it can be noticeable.

To stop this from happening many flooring contractors will use more glue on the outer edges to waterproof the OSB. But, other than that OSB is a great underlayment, and provides good cushioning, as well as thermal and noise insulation.

Should You Lay Engineered Hardwood Over OSB?

A couch on top of OSB floor

Is OSB the best option for underneath engineered hardwood, are there any special things you need to watch out for when using OSB under engineered hardwood. These are all key questions, and here’s the long and short of it…

As a whole OSB is not the best option to use as an underlayment for engineered hardwood, and the main reason is that it puffs up when it comes into contact with water, and doesn’t shrink back again. Plywood will shrink back to its original shape after it expands.

Copyright protected content owner: and was initially posted on April 21, 2021.

Rubber Flooring Inc, says that cork is the best underlayment for engineered hardwood. Foam is a very popular option and is a close second. But, cork has less give that foam and therefore, feels nicer underfoot.

However, because it’s made of natural wood it’s prone to water damage and shouldn’t be used in wet areas like bathrooms, or basements. And also shouldn’t be used in flood prone areas.

The gold standard in underlayment is rubber, but it comes with a matching price tag. And for a good mix of affordability, and quality, cork or felt are the best options.

Interestingly, in my research I haven’t come across anyone who recommends OSB underneath engineered hardwood. Therefore, if you do use it, make sure to follow the manufacturers specifications.

And unless you really want to use your OBS, or the aesthetics of the room aren’t a big priority, then you should use a different material for the underlayment other than OSB. With that being said here’s how to install engineered hardwood over OSB.

How to Install Engineered Hardwood/Hardwood Over OSB

OSB installation

Installing engineered hardwood or hardwood over OSB, is mostly preparation. And installing the boards over your OSB is quite a quick process compared to how long it takes to prepare the area.

But, prior preparation means your boards will last for a very long time, rather than failing early, and needing to be redone. Before explaining exactly how to install engineered hardwood over OSB, you’ll need to have the following tools.


  • Painters tape
  • Tape measure
  • Hammer
  • Moisture meter
  • Handheld saw
  • Electric mitre saw
  • Table saw
  • Pry bar
  • Safety glasses
  • Tapping block
  • ½” spacers
  • Moldings
  • Drill
  • Air hose
  • Wood filler
  • Inline Air regulator and compressor
  • Pneumatic Nailer or staple gun


Before beginning flooring you want to leave the boards to acclimate to their new environment for 48 hours. Every climate is slightly different and the amount of moisture in the air and the temperature will change the shape of your boards.

If you are installing it in an area that will have a HVAC system, you want to leave the boards to sit in temperature and humidity conditions that are as close to what it will be once people are living in the space.

For example, if they will be installed in a really hot city, where the HVAC system will cool the air around the clock, you should acclimate the boards by keeping them at that same cool temperature.

Copyright article owner is for this article. This post was first published on April 21, 2021.

Manufacturers recommendations for hardwood, engineered hardwood, and OSB

Beyond these preparation steps, there will also be some manufacturers recommendations for the moisture content your boards should be prior to installing them. Most require you to test a tonne of different boards in different places to make sure they’re at the right moisture content.

It’s best to follow the manufacturers recommendations for this, as the companies who manufacture the boards will have done extensive testing to see what works best.

Laying the OSB and hardwood floor

Each municipality has different building standards that need to be adhered to, so that you can get a building permit. Because they vary, this article would be far too long, to include all of them in this article. And the best resource is to do a Google search for the standards and regulations for your city/state/country.

To install the OSB and hardwood there are two main methods, you can either glue it or nail it. When you install the hardwood panels it won’t make the underlayment more solid. So, you should make sure there isn’t any movement in the OSB before moving on to installing the hardwood.

After you’ve got the underlayment of OSB down, you’ll want to hammer down the hardwood panels piece by piece. The best way to learn how to do it correctly is to watch a few videos of a professional flooring contractor installing some hardwood or engineered hardwood floors.

But, the general process is to start at one end, hammer in one board, then another using the first board, and first row of boards as the guide.

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ReadyToDIY is the owner of this article. This post was published on April 21, 2021.

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