Q: Should we be concerned about building our house in the rainy season?

A: In many instances, a home in construction often gets wet here in the Pacific Northwest. While it’s really best to plan to build a home when it’s not the rainy season, I’ve been working with the National Association of Home Builders in a study to determine acceptable moisture levels.

If you’re building a home and it does get wet, it’s important that your builder dry the structure prior to insulating the home. When drying out a structure, it’s important to NOT turn on the forced air heating (or air conditioning) system to dry the structure. Using the heating or cooling system will clog the high efficiency equipment and create a breeding ground for mold in the return air ducts. Dust will continue to be attracted to the moisture in the ducts even after you move into the home. Your builder should close off the duct work in the house during construction to keep the ducts clear.

Your builder should provide you with several measuring points taken prior to proceeding with the installation of insulation or drywall. The criteria that I recommend as a builder is to achieve 40% Relative Humidity for at least two days after reaching the critical compliance number of the wood. Moisture content should be 18% maximum at ¾ inch core readings as a matter of compliance.

This means that in the core of the timbers, bottom plates, and studs as well as the core of the floor sheathing, your builder is checking for moisture. Some builders have recorded surface numbers that are less than 12% while the core recordings register at over 44%.

I’ve met homeowners who want a lower upfront cost and find a builder who’ll go that way…it’s these cases that costs arise after the homeowner moves into the home and then must remove mold, dust and dirt in air ducts. Your builder should always be measuring everything and provide that information to you. It’s only in this way that efficiencies and energy can be measured in sustainable homebuilding.

Please submit your questions to jon@quailhomes.com or call me direct at 360.907.5800. Tune into Green Building with Jon Girod on 1550 a.m. on Saturdays at 9 a.m. or 860 a.m. at 2 p.m. and check back next week.

Please submit questions to jon@quailhomes.com Jon can be reached direct at 360.907.5800. Tune into Green Building with Jon Girod on 1550 a.m. on Saturdays at 9 am. See you next week!