4 types of gaps

Expanding on the 4 Types of Gaps

It’s a fact of life that things expand and contract… water, wood, and waistlines after the holidays.

Your floor is no different and may decrease in size this winter which will create a few gaps. Don’t worry, most gaps are a result of wood’s tendency to shrink in size as it dries out and those gaps will likely disappear come spring.

Here’s a run-down on what may be going on.

Environmental Gaps

Outside air in, inside air out. This is a typical air exchange cycle that goes on about 8-12 times each day in your home. During winter, the air that comes inside your house is usually much drier which takes out the moisture in the air that your floor thrives on. That air is also cold, and so you crank up the heater. That adds more dry air to your home and so your relative humidity (RH) plummets. In fact, your home can become drier than the Sahara desert. Despite our best efforts to minimize air exchange with quality windows and sealing our homes, the exchange still happens.

Wood of all kinds, not only flooring, reacts to dryness by shrinking. The moisture is pulled out of the wood’s capillaries, causing it to shrink like a dry sponge. To fix this you need to add back the moisture in the air by running a humidifier – preferably a whole home humidifier.

So the more extreme the outside condition, the more you will need to be diligent about controlling the relative humidity within your home. Most manufacturers recommend that it stay between 35-55%. A simple, inexpensive hygrometer can help you measure how much moisture is in the air inside your home.

Need a humidifier? Check out our guide to finding the right one for your home.

Jobsite Gaps

The environment shouldn’t take all the blame for gappy floors. Jobsite conditions, and decisions made before the floor is installed can also cause problems.

Let’s start off with acclimation. All wood products need a chance to adjust to their new home with the climate control system up and running. This is not a time for shortcuts. Acclimation takes time, but it is the installer’s responsibility to make sure that the manufacturer’s guidelines are followed properly.

Acclimation is not limited only to the flooring product. Subfloors also need to be checked for proper moisture content and acclimated if necessary. The gold standard for prepping the subfloor is that they must be clean, dry, sound and flat (level). Checking these things are a must before you lay the first board.

Proper job site preparation and following the manufacturer’s or industry’s recommended installation instructions are the best kind of insurance against problems down the road. See our installation guide that links to all of the recommended instructions for our prefinished flooring lines.

Installation Gaps

It is important to pay attention to details during installation. Here are three areas to watch closely:

  1. Start things out straight and you’ll be good to go. Improper alignment of the wood floor will create gaps at the ends and sides of the flooring.
  2. If you are gluing down the floor, pay attention to the trowel you are using. Too much or too little adhesive can have adverse effects. Check with your glue manufacturer for the trowel that achieves the right spread rate and avoids potential for gapping. Remember to change your trowel regularly – they will wear down quickly which will cause a change in your spread rate.
  3. If you are nailing or stapling down the floor, be sure to use the correct pressure for the fastener you are nailing. Too low of pressure could leave the fasteners seated too high, while too high of pressure could split the tongues. Both of these issues may not allow the following boards to sit flush.

Did you know that using the wrong fastener or pressure can also cause squeaks? Find out more about how to stop squeaky floors by using the right fastener here.

Manufacturing Gaps

This last area can be tricky, and not a common reason for gaps, but here’s a couple things to be aware of.

Flooring should be same size down the length of the strip or plank, otherwise the product may have been mis-milled or not acclimated properly. Also keep the flooring grade in mind. Some lower grades such as #2 common, #3 common, rustic, tavern, or utility can have an acceptable amount of variation and gapping.

Bowed boards can also be a problem. They keep the floor from being installed as tight as it should be resulting in, you guessed it, gaps!

Winter = Gaps

Don’t forget that some seasonal gapping is expected with all wood floors, and is considered normal. This type of gapping appears when it is very dry and usually goes away when more normal relative humidity returns.

No matter if you sell, buy, install, or own a wood floor, knowing the behavior of wood and best industry practices keeps everyone happy and loving wood floors for many years. We certainly do, and we’re here to help you with your shrinking wood floors. Expanded waistlines, not so much.

Find out more about why gaps happen here.

One comment

  1. Gisele Sherburne says:

    My floor is cupping up in u Shape is it to dry in the basement and too humid Above ?
    Humidity in Basement runs 35 to 50% and same upstairs , Although early this spring I noticed the humidity had gotten up to 80% in basement

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