{"id":807,"date":"2013-12-29T00:25:36","date_gmt":"2013-12-29T00:25:36","guid":{"rendered":"http:\/\/napervillehardwood.com\/blog\/?p=807"},"modified":"2026-01-07T04:38:07","modified_gmt":"2026-01-07T04:38:07","slug":"why-does-my-hardwood-floor-have-gaps","status":"publish","type":"post","link":"https:\/\/napervillehardwood.com\/blog\/why-does-my-hardwood-floor-have-gaps\/","title":{"rendered":"Why Does My Hardwood Floor Have Gaps?"},"content":{"rendered":"

It\u2019s that time of year again when I start getting asked the same question over and over\u2026 \u201cWhy does my floor have gaps?\u201d, or some similar version of that like \u201cCan you fill the cracks in my floor?\u201d<\/p>\n

\"Gaps<\/p>\n

It\u2019s not fun to have your floors refinished and 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.<\/p>\n

What on earth is going on? Is there something wrong with your floors?<\/p>\n

<\/p>\n

Thankfully, for most hardwood floors the answer is no.<\/p>\n

What you\u2019re seeing happen 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\u2019t.<\/p>\n

 <\/p>\n

The Reason Hardwood Floors Have Gaps:<\/h4>\n

Put simply, wood is hygroscopic.<\/p>\n

Something that is hygroscopic attracts and holds water molecules from the environment it\u2019s placed in. For example\u2026 you may have been to a restaurant with a salt shaker that won\u2019t let any salt come out because it\u2019s all clumped up? The reason this happens is because the high humidity levels in the air cause the salt crystals to absorb moisture. Salt will expand to the point that it can\u2019t come out of the tiny shaker holes.<\/p>\n

This is exactly the same type of thing that happens with wood.<\/p>\n

\"Gaps<\/p>\n

The moisture content of your hardwood floor will change depending on the relative humidity of the surrounding 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 moisture content in the wood decreases and it starts to contract and shrink.<\/p>\n

The technical term for this process is Equilibrium Moisture Content (EMC).<\/p>\n

Below is a map showing the regional EMC across the United States…<\/p>\n

\"Equilibrium<\/p>\n

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 harder and harder to open and close, as if they\u2019ve suddenly grown.<\/p>\n

Those old solid wood doors are dealing with the same EMC issue.<\/p>\n

Like these wooden doors, this expansion and contraction in hardwood floors is very noticeable in the seasonal changes between winter and summer.<\/p>\n

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 rolls 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\u2019s been holding and it begins to contract and shrink.<\/p>\n

That\u2019s when you start to see gaps forming.<\/p>\n

\"Equilibrium<\/p>\n

It gets especially bad when we have runs of freezing cold days like we experience here in Naperville and Chicago. All of a sudden everyone\u2019s furnaces are cranked right up. That\u2019s when all the moisture starts getting sucked out of the wood and those dreaded gaps start appearing.<\/p>\n

Thankfully these unsightly gaps will start to disappear when spring rolls around with its increased humidity levels and the heat gets turned down and eventually turned off.<\/p>\n

But what if you don\u2019t 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?<\/p>\n

 <\/p>\n

What Can Be Done to Control the Gaps?<\/h4>\n

One of the best ways to control the gaps in your hardwood floors is to keep the humidity level in your home the same throughout the year. Obviously, in order to do that you\u2019ll need to add moisture to the air during the drier months.<\/p>\n

The easiest way to do that is to invest in a humidifier and set it to 45 \u2013 55 percent. (Gaps start to appear in your floor when the humidity level gets below 40 percent).<\/p>\n

By doing that the relative humidity in your home will stay stable and your hardwood floors won\u2019t expand or contract as much during the year \u2013 which means far fewer and also smaller gaps.<\/p>\n

When it comes to humidifiers, you have two types to choose between.<\/p>\n

The first kind is a permanent installation that\u2019s connected to your furnace and works throughout the whole house. It gets integrated with the blower system and draws water directly from the houses main water supply. These humidifier systems are very low maintenance and quite reasonably priced.<\/p>\n

Here\u2019s a video I found on YouTube that describes this type of system (skip the first 30 seconds)\u2026<\/p>\n