Lumber used for framing should be dried to a moisture content (M.C.) of what percentage?

• A. 15%
• B. 19%
• C. 22%
• D. 25%

Answer: (B)

Moisture content controls how much lumber will change in size after it’s installed. For framing, lumber is considered dry enough when it’s around 19% moisture content. This level is a practical balance: it’s dry enough that the wood won’t shrink a lot once inside a building, which helps keep walls square and fasteners tight. If lumber is wetter, like 22% or 25%, it will dry and shrink more after installation, leading to gaps, misaligned framing, and nailed joints loosening as the wood moves. If it’s drier than 19%, like 15%, it’s more likely to absorb moisture from the indoor environment and swell, which can also cause movement and fit issues, though the changes are typically less dramatic than with overly wet lumber. So 19% is the standard target for framing lumber to achieve stability in typical indoor conditions.