CSLB General Building (B)Framing and CarpentryMedium
A carpenter examines a grade stamp on a piece of framing lumber that reads 'S-DRY.' What does this designation indicate about the lumber?
- AThe lumber is rated for exterior exposure without additional treatment
- BThe lumber was surfaced at a moisture content of 19% or less
- CThe lumber has been kiln-dried to 15% moisture content or less
- DThe lumber is graded for structural use only in dry, non-seismic regions
Show answer & explanationAnswer & explanation
Correct answer: B. The lumber was surfaced at a moisture content of 19% or less
'S-DRY' on a grade stamp means the lumber was surfaced (S) when its moisture content was 19 percent or less at the time of manufacture, per American Lumber Standard grading rules. This distinguishes it from 'S-GRN' (surfaced green, moisture content above 19%).
Why the other options are wrong
- A. Exterior exposure rating is unrelated to the S-DRY moisture designation.
- C. 15% is the KD (kiln-dried) threshold used by some mills, not the general S-DRY standard.
- D. S-DRY refers to moisture content at surfacing, not seismic or regional use.
Lumber Grade Stamp - Moisture Content
Grade stamps include a moisture content designation such as S-DRY (surfaced dry, ≤19% MC) or S-GRN (surfaced green, >19% MC) at the time of surfacing.
- S-DRY = 19% or less moisture content at surfacing
- S-GRN = surfaced green, moisture content over 19%
- Grade stamp also shows species, grade, and mill/grading agency
Memory trick: 'S-DRY stays under nineteen, keeping shrinkage lean.'