Why Does My Wood Floor Have Gaps

You may not have noticed but this is a seasonal occurrence.  The boards are tight in the summer and then, just a few months later, when things start to get colder, they start opening and being full of gaps.  Is there something wrong with your floors?  Thankfully, for most wood floors the answer is no.

What’s happening is perfectly normal for all things made of wood in your home, including your wood floors. There is a very simple explanation for why some months of the year you see gaps in your floor and other months you don’t – wood is hygroscopic.

Something that is hygroscopic reacts with the moisture level in the air. For example… sometimes salt will come out of the salt shaker and other times it won’t.  The reason this happens is because the high humidity levels in the air cause the salt crystals to absorb moisture. Salt will expand until it can’t come out of the tiny shaker holes…wood is similar but expands at a slower rate (fyi a trick is to put rice in with the salt and let it absorb the moisture instead).

The moisture content of your wood floor will change depending on the relative humidity of the air in your home. The moisture content of the wood will increase as the humidity level in the air increases. This process will make the wood expand. In the same way, when the humidity level in your home drops, the woods moisture content decreases and it starts to contract and shrink.

In the past you may have experienced wood doors in older houses that open, close and lock perfectly fine in the winter months. Then summer comes along with its humidity and the same doors start to get stuck, as if they’ve suddenly grown. Those old solid wood doors are dealing with the same moisture content issues.

Like these wooden doors, this expansion and contraction in wood floors is very noticeable in the seasonal changes between winter and summer. In the hotter summer months your house is open, the humidity level in the air is higher and the wood in your floor absorbs moisture and fully expands. Then the colder winter months come around, you close your home up tight and crank up the heat. When you do this, the humidity level in your home drops and the wood in your floor releases the moisture it’s been holding and it begins to contract and shrink.  That’s when you start to see gaps forming.

The more you crank up the heat, the more the gaps appear.  Thankfully these gaps will start to disappear when spring rolls around with its increased humidity levels and the heat gets turned down and eventually turned off. But what if you don’t want to wait for summer? Is there anything that can be done to close the gaps a bit now and keep the floor tight throughout the year?

What Can Be Done to Control the Gaps in wood floors?

One of the best ways to control the gaps in your wood floors is to keep the humidity level in your home the same throughout the year. Obviously, in order to do that you’ll need to add moisture to the air during the drier months.

One way is to invest in a humidifier and set it to 45 – 55 percent. (Gaps start to appear in your floor when the humidity level gets below 40 percent). By doing that the relative humidity in your home will stay stable and your wood floors won’t expand or contract as much during the year – which means far fewer and also smaller gaps.  Another option is to leave a saucer of water on the radiators in the winter which will evaporate daily and replenish.  This is a trial and error solution but much cheaper than a humidifier.


In Conclusion…

So as you can see, if you have gaps in your wood floor there’s no need to panic. Wood is a natural product that predictably reacts to the environment it’s placed in. How much it expands and contracts completely depends on the weather and the humidity levels you maintain in your home.

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