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Ask Eli - Cracks In Hardwood Flooring

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I have Cypress hardwood floors and am noticing cracks along some of the ends. Understood this is somewhat normal with this hard of a wood but is there any product I can use to minimize cracks or splintering where they have started? Folks are catching their socks in a few areas! Thanks in advance!! - Scott


Great question Scott.  The first thing we need to do is determine if there is something causing this problem.  There are a couple things we should look at.  As you said, this type of wood is prone to cracking (or checking) at the ends.  Cypress is a very hard wood and it is very brittle. This combination makes cracking at the ends a pretty normal part of the drying process for Cypress. There aren't really any products you can use to stop it at this point, but read on and maybe you will find something else that will help you.

Do you know if the cracks were there when the flooring was installed?  There are often lots of boards that are already cracked when Cypress flooring is purchased.  The installer normally tries to use the cracked ends at the walls and edges of the floor and then they can trim the cracked parts off. Some installers consider the cracking to be a normal part of the product and just install it without paying any attention to the cracks.  I know that there are some hardwood flooring installers that refuse to install Cypress at all because of this cracking, and because the boards sometimes split when they try to nail them down.

If the cracking has happened since the floors were installed, or has gotten noticeably worse, then you may have a problem with low humidity.  Low humidity can be caused by natural climate conditions, freezing temperatures, or using a wood burning fireplace to heat your home. The ideal humidity in your house should be about 45%.  If it is lower than this, you will have problems with cracking in flooring and sheetrock.  You may also have health problems such as dry and cracking hands, scratchy throat, and nose bleeds.  If the humidity in your house is much more than 45% then you will have condensation on windows, rot, and mold problems.  Here are some other resources that discuss humidity inside the home:  The Weather Guys @ USA Today, and USA Today - Wrong humidity turns your house into a hassle.

To find out what the humidity is in your house you will need a hygrometer, which is an instrument for measuring relative humidity in the air.  If the humidity is low, then you will need a humidifier to add humidity to the air in your house.  For a temporary solution you can use a small humidifier that you can buy at a department store. For a long term solution, you may want to get a humidifier that ties directly into your HVAC system and keeps your whole house at a constant humidity.

If low humidity in your house is the problem, you should raise the humidity incrementally. I would recommend raising it by about 5% and then keep it at that humidity until the hygrometer shows that your house is staying steady at that humidity for a couple weeks.  Every part of your house will need to stabilize at that humidity before you want to raise it again.  So, for example, your Cypress flooring will soak up some of that humidity in the air, raising the humidity in the flooring and lowering the humidity in the air.  You can set the humidifier at 45% but it may take a while for the air to stay steady at that humidity as some of the humidity will soak into the rest of the house. As this humidity soaks into the Cypress flooring, it will expand making the cracks and seams tighter.

If the cracking in your Cypress flooring just happened this winter, it may also be a humidity problem.  The colder the temperature outside, the lower the humidity will be.  This winter has been much colder here in Washington State so we have seen more of this kind of cracking problem this winter than normal.  If you live in a climate that normally has plenty of humidity then the problem will likely correct itself as the humidity outside returns to normal. You will want to keep an eye on it in the future during cold winters, and have a humidifier available in case you need it.

If the problem was humidity and you have corrected it, then you will need to leave the cracks in the floor alone for a few months.  The cracks should get smaller as the floor's humidity stabilizes.  When you are sure the cracks are done shrinking or moving, you can decide if you want to do something to fix them.  They may get tight enough that you don’t need to do anything if you don’t want to.

Here are a couple suggestions for fixing the cracks in your Cypress flooring.  If there are splinters or parts that are raised up above the surface of the flooring then you may need to do a little sanding to get them back down.  You should check with a local flooring store to find out what to use to refinish these areas.  They should also be able to set you up with a pre-finished putty appropriate for your type and color of flooring.  The pre-finished putty is nice because you don't have to do anything with it after you use it. It will already match the flooring. If you need to sand a spot and then putty, you will want to use an unfinished putty and then put a finish over it when you are finishing the sanded area.

You don’t want to putty the cracks until you are sure they are done moving.  If you putty them too early, and the cracks shrink more, then the putty will squeeze out of the cracks. Fixing the cracks should be pretty easy and a local flooring store will be able to help you figure that part out.  The hard part is figuring out what is causing the cracks.  The most common reason is a humidity problem.  If humidity is not the problem then it is probably just the fact that Cypress is prone to this type of cracking.  Cypress sure makes a beautiful floor though.  I hope this has been helpful and informative. Let me know what you figure out.  Thanks for the question.

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