Q: I enjoyed your recent column on silencing squeaky floors. I have one more question for you that I really hope you can answer.
Last summer we had 1,000 square feet of Brazilian cherry professionally installed on the first and second floors of our home. It cupped. We then had the crawlspace under our house lined.
I bought a hydrometer and took humidity readings. Our bedroom on the second floor and other rooms still seem to have too much moisture — 60 percent after we wake up in the morning — before showers.
What should I do? I have noticed a difference in the cupping when we have “controlled” the humidity. We run fans continually under the house in the encapsulated space. We also run fans in the living room and in our bedroom.
I am heartbroken about our floors and at a loss as to what to do. We have spent so much money on the floors and the crawlspace liner.
A: As you point out, “cupping” of your newly installed floorboards is likely the result of excessive moisture. One possible source of the problem might be that the wood flooring was not allowed to stabilize before it was installed. If the wood contained excessive moisture at installation, natural warps and cups appear as it grows accustomed to its new environment.
Although a possibility, we don’t think it is likely since the floor was installed during the summer and the problem seems to have arisen during the winter. Rather, it’s more likely that the cupping you are experiencing is the result of high relative humidity in a warm house during a cold, wet winter.
Cupping is the result of wood trying to return to its natural shape. Look at the end of a board. If you see growth rings that are concave the board is likely to cup. When installing similar boards, it is best to install them with the cup facing down. Whatever fasteners you use — nails or screws — will inhibit the boards from taking their natural shape.
Excessive moisture can wreak all kinds of havoc on home and owner, including itchy skin and nasal passages, mold growth, water damage to organic materials and, in extreme instances, rot.
Reducing the interior relative humidity provides a solution to these problems. You have already experienced it downstairs from putting the liner in the crawlspace. Taking the next step is going to require a little detective work.
You’ve taken the right first step by checking the humidity level to verify that moisture levels are high. We agree that 60 percent relative humidity is a bit high for a home’s interior and indicates a problem. Now the challenge is to find the source.
Some possible causes of excessive moisture might be outside landscaping (are you surrounded by trees?), defective insulation, lack of ventilation, or some of your living habits such as air-drying clothes inside. It may also just be the quirkiness of your home.
If you have exhaust fans, use them. If your bathrooms do not contain exhaust fans, install one in each bathroom where you bathe or shower. In the meantime, open the window while running the bath or shower to vent the warm, moist air outside.
There are other more detailed steps you might take. Installing a whole house fan encourages even air distribution throughout the house to eliminate cold spots.
Consider installing a dehumidifier to reduce the relative humidity in the home to 50 percent or less. A dehumidifier works by removing moisture from the air by directing the air over cold coils, wringing the water out and channeling the condensation to the outside.
In researching our answer to your question we came across a story from a nurse who came home from a trip out of town to find her house unbearably humid. She’d recently purchased a dehumidifier that she immediately put into service. She claims that within “about half an hour” of installation the humidity level was reduced to around 50 percent. Even though this story is merely anecdotal evidence, we give it some credibility. You can read her story online at www.allergynursing.com/moldy/dehumidifier.html.
A good heating, ventilation and air-conditioning company can help you with installation of a dehumidifier, if you choose to go that route. But we encourage you to learn something about them before you approach the pros. This Canadian Web site is a good place to start: www.cmhc-schl.gc.ca.
Finally, we caution you that installing a dehumidifier is not a “silver bullet” that necessarily will solve the problem. Start with reducing the sources of moisture in your home first. That may just do the trick.