2.2 KiB
2.2 KiB
Wood Shrinkage
General
- All building designs must account for wood shrinkage as framing dries.
- Wood continues to shrink until it reaches its equilibrium moisture content (EMC), typically 8–12% moisture content for most U.S. structures.
- The contractor shall prepare and enforce a moisture control plan to minimize water in wood framing.
- Drywall installation is prohibited until all wood framing has a moisture content below 15%.
Construction Considerations
- Contractors must understand framing tolerances, shrinkage, and interactions with dissimilar materials.
- Rough openings in exterior walls shall be upsized approximately 1/2" to accommodate shrinkage.
- Provide 1/8" wide gaps between sheathing panels.
- Plumbing systems must accommodate differential vertical movement:
- Include vertical expansion joints
- Allow gaps around horizontal runs
- Avoid horizontal runs within load-bearing studs
3. Moisture Control During Construction
- Take precautions to limit moisture exposure of lumber.
- If lumber becomes wet, dry it to ≤15% moisture content before installing finishes.
4. Estimated Wood Shrinkage
- Assumes all lumber is Southern Pine with initial moisture content of 19% and final moisture content of 10%.