Wood Flooring and Humidity Levels

Dover Flooring Blog

November 8th, 2014

Why are humidity levels important for a wood flooring installation job and for the wood flooring itself going forward?

Wood flooring is made of wood (duh!). The wood in the hardwood flooring was once a living and breathing tree. During the tree's lifespan, the wood constantly had moisture flowing through it to feed the tree. So, while the term "wood flooring and water don't mix" is accurate, the fact is hardwood flooring still needs some moisture to keep from drying out and remaining viable.

Gapping caused by low humidity levels

If your home is allowed to become too dry, your hardwood flooring will contract (shrink). If the surrounding air remains too dry for an extended period of time, then the wood flooring (and your furniture and pretty much anything in your home made of wood) could start to crack. When you see cracking in a hardwood floor or in your wood furniture it will almost always be from lack of moisture. Just as your skin will start to crack when it's dry so will your hardwood floor. And just as this is bad for your skin it's also bad for your hardwood flooring. Expansion and contraction in your hardwood flooring is fairly normal but cracking is not and really can't be fixed. A cracked board will remain cracked. Replacement is really the only option to get rid of a cracked floor board.

Cupping of hardwood flooring

Now, too much moisture is also bad for wood. Too much moisture can cause the hardwood flooring to expand so much that it can actually cup or buckle. As each individual board making up a hardwood flooring installation absorbs moisture out of the air they will start expanding. Each hardwood flooring job should have adequate expansion gaps around the edge of the room allowing for this normal expansion. Without adequate expansion gaps (and too much moisture in the air) the hardwood flooring will cup (the edges of the boards will raise while the middle stays down). With extreme moisture absorption the flooring will start to buckle.

Cupping caused from too much moisture

So you can see that too much moisture or too little moisture can really damage your hardwood flooring. Just the right amount of moisture is ideal. Keeping your home with a relative humidity level between 35% and 55% will keep the wood flooring from gapping in the dry months and cupping or buckling during the humid months. You can purchase a humidistat from your local hardware store to monitor the health (humidity levels) of your home.

If your home is too dry, you may need to purchase a whole house humidification system that attaches to your furnace (as a matter of fact, if you have hardwood floors in your home you should definitely have a whole house humidification system) or smaller 1 room humidifiers set up in or near the areas that you have wood floors. With a humidistat and some type of humidification system you should be able to keep your home within the required humidity levels for optimal hardwood flooring performance. This will minimize the fooring's expansion and contraction cycles. If you kept your home at a constant humidity level of let's say 41%, you really shouldn't have any floor movement at all (theoretically). 

Wood and water don't mix but hardwood and some moisture is critical for a healthy hardwood floor that will last for years and years and years......

Next week we'll talk about the differences between an engineered floor and solid hardwood as it pertains to expansion and contraction. How wider width planks also affect performance when it comes to expansion and contraction. Also, dimensional stability. How it's different between solid hardwood flooring and engineered hardwood flooring and how different species are affected by similar moisture levels......