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Power Outages: What to Expect from Your Hardwood

Hi Neighbors!

I hope you all are restored by now. We want to thank all of our VEC workers and the out of town guys for working so hard these past weeks to keep us all turned on!

We have been getting a lot of phone calls now that homes are reheating with concerns of cracking, buckling and gaps. 

Because wood flooring is a natural product, it has some moisture in it at all times. The content of this moisture will change as the moisture in the environment changes. As the ambient air dries out, the wood will also dry out and shrink. This shrinking is what causes the appearance of gaps between the boards.

When the outside temperature drops below freezing, most of the moisture in the air will drop out as frost, snow, or ice so during long periods of below freezing cold, there is much less moisture in the air, and you will probably notice an increase in shrinking, gapping and cupping.

While wood floors are made from "dead" trees, the flooring reacts to temperature and humidity changes inside your home as if it were alive. Your skin reacts to low humidity. So does wood flooring. High humidity and high temperatures affect your skin. These conditions also affect your wood floors. What is comfortable for you is also ideal for your wood floors. 

It doesn't matter if your wood floors are solid wood, engineered wood, or laminate. It doesn't matter if the wood is oak, mahogany, or bamboo. It doesn't matter if the wood is nailed down, glued down, or floating. Regardless of the installation method, all wood flooring absorbs or loses moisture as conditions change slowly or rapidly inside and underneath your home. 

Every wood flooring manufacturer only allows their products to be installed indoors, in a stable, maintained environment. This means, in order for the wood flooring to perform as designed, the temperature and humidity conditions inside your home must be kept continuously within a certain range. This range varies slightly depending on the manufacturer and type of wood flooring. Generally, the required range is between 60-80 degrees with a relative humidity range of 35 percent to 55 percent. (See the National Wood Flooring Association Guidelines

Wood floors don't like sudden indoor changes. So what happens if you lose power for 8 days straight and don't maintain the temperature and humidity within these requirements!? The humidity drops quickly and the floor shrinks! You may see gaps suddenly appear along the sides or ends of the boards. The boards themselves may split or crack in the centers or at the ends, or both. This damage is also permanent. Rising humidity will not remove the splits, although some gaps may disappear. 

To add insult to injury, none of this damage is covered by the flooring warranty. It is your responsibility to make sure you have a stable environment in your home. 

When the humidity jumps, as in your power is restored, the floor will swell and expand. Wood floors are installed with gaps around the edges (covered with baseboards) to allow for some expansion. The gap along each wall is usually equal to the thickness of a board. But if the humidity really jumps quickly, the floor can expand beyond these expansion gaps. Just think about it. Let's say the boards are each 5" wide and your room is 15' across. So you have 36 boards across the room. If each board swells 1/16", the entire floor grows more than two inches! The gap on each side of the room is probably 1/2" or less. That means a total planned expansion of 1" in each direction. If your floor gains an inch beyond the existing gaps, where does that extra wood go? Up! You wind up with a buckled floor. It's like walking on a trampoline. Once the humidity drops, the floor should shrink back, but the edges of each board are now crushed. They are permanently damaged. 

Does every wood floor fail because the inside temperature/humidity levels greatly fluctuate? No. Do wide temperature/humidity swings greatly increase the odds of flooring failure? Yes. If your wood floor self-destructs because of a rapidly changing indoor environment the blame, unfortunately, falls on the homeowner. 

Here are a few points to be aware of with wood movement.
  • Width of Material
    The wider the board, the more movement will occur (the term "board" technically refers to wood 1 1/2 in. thick or less, but for this article its use will refer to wood typically used by finish carpenters). It's a direct proportion: an 8-in. board will move twice as much as a 4-in. board, and a 12-in. board will move 3 times the amount as a 4-in. board. And it's important to keep in mind that a glued-up panel behaves basically as one wide piece of lumber.

  • Grain orientation matters
    Boards are characterized as being either "flat sawn" or "quarter sawn." Quarter sawn lumber (also referred to as "rift sawn" or "vertical grain") shrinks and expands roughly half as much as flat sawn. Most over-the-counter finish material is flat sawn, and you should assume flat sawn values unless you're sure your material is quarter sawn. Quarter sawn lumber has annular rings that are oriented between 45 and 90 degrees to the board's face.

  • Species affects the amount of movement
    Wood movement depends in part on the species. A 12-in. wide western red cedar board will fluctuate 1/8 in. while the same size maple board will fluctuate 1/4 in. The formula for calculating wood movement is complex and extremely accurate, but tedious. One simple rule of thumb serves as an approximate guide to predicting wood movement: "Most species of flat grain material will change size 1% for every 4% change in moisture content." Applying this formula to a situation where the seasonal EMC ranges from 6% to 10%, a 12-in. wide board will change dimension 1/8 in.

Please feel free to give us a call with any questions on your flooring. We will help with information as much as we can. 


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