What Are Acceptable Gaps in Hardwood Floors and How to Fix Them

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what are acceptable gaps in hardwood floors

If you have been thinking about rejuvenating your home, new flooring is a great way to do it. 

Your home’s floors contribute so much to the energy and feel of the space. By installing new flooring, you can create a whole new space with the aesthetic you are looking for. 

Hardwood flooring is a classic option for home flooring that is both durable and stylish

While hardwood is a long-lasting choice, it comes with its own set of problems. Gaps between boards are common and need to be addressed as soon as they happen. 

If your flooring has been properly installed, you shouldn’t have to worry about gaps. A knowledgeable, experienced flooring professional will be able to work out any issues. 

However, if your hardwood floors have gaps, it is important not to panic. There are ways you can deal with them and ways to avoid them in the future. 

In this article, we have laid out everything you need to know about gaps in hardwood floors. 

Some of the things you need to consider about hardwood floor gaps include: 

  • Gaps that are acceptable for flooring 
  • How to avoid gaps
  • How to fix gaps once they have occurred

By understanding everything you can about this phenomenon, you can have a floor you love for many years. 

Why Do Gaps in Hardwood Floors Occur? 

why do gaps in hardwood floors occur

While hardwood floors are a fantastic choice for almost any home, they can be incredibly sensitive. 

Wood is a great material that has so many different uses and a classy, high-quality look. Unfortunately, it is also very sensitive and may not be stable in different weather conditions. 

This means that it can warp and change in size depending on certain factors. 

The moisture content of the air and the temperature in a room can severely affect wood. Because of this, it is crucial that the wood is properly prepared and handled correctly before installation. 

If you live in an area that has a lot of moisture or humidity, your installer should take this into consideration. 

Letting the wood acclimate to the room it is to be installed in is a very important step. Doing this will allow you to keep your hardwood sealed no matter how the temperature or humidity changes. 

Hardwood flooring may also simply shift and move around as it gets older. When this happens, there are ways you can fill in the gaps, which we have outlined below. 

Acceptable Gap Sizes 

For the most part, there are no acceptable gap sizes for the slats on your hardwood floors. 

While the planks will sometimes shift and move around, this doesn’t mean that the gaps should be noticeable. Usually, these movements will be so small that you won’t notice a difference just by looking at the floor. 

If you are noticing the gaps and they are immediately visible, this is a good sign that you have an issue. 

The only place where a gap is acceptable with hardwood flooring is the floor’s expansion gap. 

An expansion gap is a small area between the floor and the baseboard on the wall. This gap should be there to allow for small movements and expansion due to heat and moisture. 

Without the expansion gap, you could end up with cracked slats or cupping. You may also see certain planks starting to press against each other too much and forming mounds. 

While you need an expansion gap around the perimeter of your floors, it will be very small. Generally, a hardwood floor expansion gap should only be between 10 and 15 millimeters. 

Avoiding Gaps 

avoiding gaps

The best way to avoid gaps in your hardwood floor is to have them installed correctly in the first place. 

A good installer will know all the ways to properly prepare your hardwood before permanently putting it in place. 

Before your hardwood planks are installed, they should be acclimated to the room they will be in. This means that they should be left in the room for at least 72 hours before anything happens with them. 

Doing this will allow the wood to expand and contract in accordance with the heat and humidity. Then, it can be installed without you having to worry about it moving around or creating gaps. 

It is also a good idea to install hardwood flooring in the driest possible months. 

This way, once the humidity hits, the wood will simply expand into the expansion gap. It won’t shrink down when the weather gets dryer like it would if you installed it during the winter or summer. 

Fixing Gaps 

If your hardwood floor has developed gaps, there are ways that you can fix them

One of the most common ways to fix gaps in your hardwood flooring is to use wood filler. Wood filler is made up of wood particles and glue and comes in all kinds of colors. 

If the gaps in your flooring are small, wood filler is a great option. It is easy to apply and can match up with the current look you have. 

If you have bigger gaps, these may need to be filled with extra material. 

You can use smaller planks or you can use rope and wood filler. Rope and wood filler is the best option because they will fill the gaps and make the filler seamless. 

Frequently Asked Questions

faq what are acceptable gaps in hardwood floors

How do you stop drafts coming through floorboards?

The best way to stop drafts coming through your floorboards is to fill them. However, if the gaps are too big, insulation can work as well. 

If you have a basement or crawlspace, installing insulation under the planks can work very well. 

Is it worth insulating under floorboards?

Even if your floorboards are completely sealed, you may need to insulate them. If your floors are raised, this may be a necessary step. 

Insulating your floorboards can save you money on utilities and electricity.

What is a suspended floor?

A suspended floor is a floor that sits above a basement or crawlspace. These types of floors need to have all gaps closed and sealed. 

If your suspended floor has gaps, it could be a safety hazard and at the very least be very drafty. 


If your hardwood floor has gaps, it can be very distressing. Luckily, by following the steps above, you can fix the issue and enjoy your floor for many years. 

Knowing how you can avoid flooring gaps can help you ensure that your home is safe and secure. 

Photo of author


Michael J. O’Connor is a writer and marketing specialist from the Bay Area of California. A graduate of Sonoma State’s Creative Writing program, he spent many years as a contractor and carpet layer, learning the ins and outs of flooring and general contracting. When he’s not typing away at his desk, he enjoys hiking with his dogs, woodworking and collecting rare books. See full biography here.

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