Is 20% moisture too wet for drywall? What to ask your builder

It is a common standoff on new homes. The builder wants to hang drywall next week, the studs read about 20% on a moisture meter, and the entry doors aren't in yet. The Department of Energy's Building America Solution Center, citing ENERGY STAR, says framing should be tested and kept at 18% or below before walls are closed, and dried with fans, dehumidifiers or gentle heat if it reads higher. The Gypsum Association tells installers to confirm that wood framing does not exceed the moisture limit set by the applicable standard and building code.

Austin builder Matt Risinger, writing in the Journal of Light Construction, treats 19% as a hard ceiling and reschedules the drywall crew if any piece reads higher. Kiln-dried studs should arrive at 12% to 14%, he wrote, and settle at about 10% to 12% after a year of heating and cooling. Once framing loses more than about 5 points behind finished walls, the shrinkage shows up as cracks over doors and windows, nail pops and squeaky floors and stairs. A stud at 20% still has 8 to 10 points to lose.

The doors matter as much as the reading. GreenBuildingAdvisor editor Martin Holladay gives the usual order: roof, windows and doors, then a short stretch of temporary heat, then insulation and drywall. Peter Engle, an expert contributor on the same forum, warned that propane salamander heaters put extra moisture into the air, and that pinless meters find wet spots but can be well off on absolute numbers.

Before the board shows up, get three things from the builder in writing: a maximum framing moisture of 18% or 19%, dated readings from several spots on each wall, and a plan to close and dry the house first. Building America guidance says to drive meter pins 1/4 inch or more into the wood, parallel to the grain, and to skip the cut ends.