Reader Question: I have a customer that built a timber frame building approx. 5000sq ft on one level. The heating system that was installed is drying out the building and the birch flooring and we are wondering what the recommended humidity levels should be through out the year. Can you suggest anything?

Answer:

Expert #1 – J Campbell, Delson Lumber

It sounds like they may had been supplied unseasoned (green) flooring – which is a No-No – or the builder failed to properly dry-store the flooring prior to installation. Properly dried flooring (8% to 12%) should be very stable.

I would recommend calling the National Hardwood Flooring Association @ 800-422-4556 or www.nwfa.org or the e-mail for their technical department is [email protected].

 
Expert #2 – Jack Costantino, Timber Frames Unlimited, LLC

Here are some “Rules of Thumb” relative to Relative Humidity (RH): “To prevent window condensation during the heating season, the recommended indoor RH is 30 to 50 per cent. When it is below -10°C (14°F) outdoors, recommended indoor RH is 30 per cent.” These levels can be maintained with humidifiers installed in line with a forced air system. If they’re supplementing heat with woodstoves or fireplaces a simple wall mounted hygrometer in multiple locations will tell them the humidity levels. Wood burning accelerates drying the air.

Also, I wonder if the flooring in particular was allowed to “acclimate” in the conditioned space for 7-10 days before installation. It’s a common problem for wood flooring to be delivered from an unconditioned environment in a warehouse, exterior storage shed, etc. and be installed too quickly.

Expert #3 - Edward Fernandez, Texas Timber Frames

The customer should make sure that the interior conditions of their home should stay between 30% and 50% relative humidity and be between 68 and 72 degrees. This will require the use of a hygrometer which measures relative humidity which you can pick up at a local electronic store or on the internet.

Tags: building a timber frame home, relative humidity, timber, Timber Frame Business Council, timber frames

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