Acceptable Gap in Hardwood Floor – What is the Right Gap?

Hardwood floors are a nature-friendly and somewhat elegant choice. If you have hardwood floors in your house no doubt you appreciate their appeal. But at the same time, they come with a vice. There are gaps in the floor. Although the gap is inevitable, how much is an acceptable gap in hardwood floor?

You cannot tell wood bars to not expand or to not shrink. They are natural materials and they react to environmental changes. But at some point, the gap becomes too big and causes problems. But as long as the gap is natural it is acceptable which can be up to the thickness of a quarter.

Generally, a hardwood floor will have gaps between the floorboards during the dry seasons. And the gap will close when the humidity is back in the air. But if the gaps don’t close and they are quite big, it is a problem. Let’s see what can be the reasons behind this problem and how to solve it.

Acceptable Gap in Hardwood Floor

What is the Acceptable gap in the hardwood floor?

And what amount of gap is acceptable and expected depends on various issues. Firstly, the type of wood you have used on your floor. Some floorboards will shrink more than others meaning they will have larger gaps between them. Maple or Hickory floorboards show bigger gaps.

Another factor is the type of cut that was used to make floorboards. Because that has a big effect on the grain pattern of the boards and that affects the water absorption. So, plain or flat sawn wood will expand or shrink more than rift and quarter sawn wood.

And the other factor is the width of the floorboards. The wider they are, the more they expand or shrink. So, if we are talking about 2 ¼” floorboards the acceptable gap size will be 1/32”. And if the floorboards are 5” in width then you can expect gaps up to 5/8” thick. 

Are gaps normal in hardwood floors?

Whether you like it or not, there will be a certain amount of gap between the floorboards in a hardwood floor. It is only natural. And you have signed for it knowingly. So, you cannot complain about that. But what you can complain about is a large gap that won’t fill up even during the wet seasons.

The reason there is a gap between two wooden floorboards is simple because they are made of wood. And wood absorbs water whenever the surrounding has more moisture contents than it has. And the amount of moisture content in the surroundings means the air changes depending on the season.

So, during the dry seasons like winter, there is less moisture in the air than there are in the floorboards. So, moisture comes out of the floorboards and they shrink as result. And the opposite happens during the wet seasons like summer. Because of this process, a certain amount is normal in hardwood floors.

How to solve the gap in the hardwood floors?

Now, let’s see the solutions to this problem.

Use a humidifier in the house

The main reason the floorboards shrink and create gaps is the lack of humidity in the air. And the humidity in your house can drop because of your heater and ventilation system. So, if you can adjust the humidity level the floorboards won’t shrink to create gaps. For that, you can use a humidifier in your house.

Fill the gaps with wood putty

If the gaps in your hardwood floor aren’t closing even during the wet season, you will have to do it yourself. You can use wood putty to fill in the gaps. Wood putty is better than wood filler because it is more elastic. So, it will remain flexible even after drying up. 

Fill the gaps with sawdust

If you don’t want to use wood putty, you can use sawdust and wood glue. The combination will be a flexible filler for the gaps just like wood putty. You can use wood glue such as PVA or polyurethane. The benefit of this method is sawdust is readily available and almost free. You just need to buy the glue.

Fill the gaps with ropes

Another method is filling the gaps with ropes. You will stain the ropes to match the color of the hardwood floor. Then you can just put the ropes on the gaps to fill them up. 

Fill the gaps with wood stipes

Another great way to fill the gaps. Use the same type of wood that is used in the floorboards to make the stripes. And do this filling in the wet season when the gaps are the smallest. Cut the stripes according to the size of the gap and put them on the gaps to fill them up.

How to prevent gaps in hardwood floors?

Prevention is better than cure. Let’s check how to prevent the gaps.

Acclimate the floorboards

This is the first and most important step toward the prevention of gaps. If this is done correctly the gaps will be very quick to appear and the most horrible of size. Make sure the floorboards are acclimated to have the proper amount of moisture content. Keep the heater and ventilators on during the process.

Install the hardwood floor properly

This is important. Because if you don’t install the floorboard at the correct angles and don’t align them properly there will be gaps very soon. Make sure they are properly aligned and tightly fitted. This will prevent any gaps from appearing very soon.

Maintain proper humidity in the house

This is a long-term process. If you have decided to have a hardwood floor in your house. You have to do some maintaining of it. As you know that the humidity inside your house plays a big role in creating gaps in the hardwood floor. So, try to keep the relative humidity inside your house between 35%-55%.

Use better wood and floorboards 

As we have mentioned before certain types of wood are better than others in terms of shrinking and expanding. Use those to prevent big gaps in the floor. And try to buy floorboards that have been made from the rift and quarter-sawn wood. They expand and shrink less. And also use lees wide floorboards for the same reason.


Check the section below for the most commonly asked questions of the users.

How much does the hardwood floor expand and contract?

It depends on a lot of factors such as the type of wood and type of woodcut that has been used to make the floorboards. And also depends on the width of the floorboards. So, depending on all of these hardwood floors can expand or shrink from ¼ to ½ inch. 

How much space should be between hardwood floors and walls?

You should be leaving 10 to 15 mm of space between the hardwood floor and the walls all around the room. You can use appropriate size spacers against the walls to make sure the gap is of the right size. The rule of thumb is for ¾ inch floorboards ¾ inch space should be kept.

What happens if an expansion gap is not left?

As hardwood floors are made of wood and wood will expand during the wet season. For this, the floor as a whole expands. But if an expansion gap is not left then the floorboards can warp, rise up and even break. 


So, if you are going to install hardwood floors in your house you know almost everything about the gaps in them now. The acceptable gap in the hardwood floor depends on various factors. But it is not usually more than the thickness of a quarter. And seasonal gaps are natural and unavoidable. 

Although inevitable there is a limit where the gaps become unacceptable. We have discussed that limit for different types of wood, woodcuts, and floorboard sizes. Check out if the gaps in your hardwood floor are acceptable or not based on that information. If not fill them up using a method you prefer.

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