Drying
Seasoning defects and moisture limits
Checks, warping and honeycombing come from uneven drying. Moisture limits decide whether timber can decay in use.
This article was drafted with AI assistance and has not yet been reviewed by an expert. Check important figures against a standard or your contract before relying on them.
Defects caused by drying
- Checks are surface cracks that form when the outside of a piece shrinks while the inside is still wet. They occur more often at the ends, which dry faster. A deep check can hold water and encourage rot.
- Warping (bow, cup, twist) happens when different parts of a piece shrink by different amounts. Tangential shrinkage is larger than radial, so the way a board is cut from the log affects how it distorts.
- Splits and honeycombing are internal or through cracks. Seasoning defects are a main cause of them.
How to limit them
- Dry slowly enough that the surface does not shrink far ahead of the core. Drying schedules for kilns balance temperature, humidity and time for each species and thickness.
- Seal or protect the ends of valuable pieces during air drying.
- Stack with evenly spaced stickers so air moves through the pile and the weight keeps boards flat.
Moisture limits in use
- A maximum of about 19 % moisture content is commonly recommended for untreated timber in service.
- Decay fungi need moisture content above roughly 25 % (dry-weight basis) to attack wood. Established decay can continue at around 22 to 24 %.
- Wood that stays below those levels can remain sound for very long periods.
Moisture content figures here are on the dry basis; see the article on moisture content for the difference to the wet basis.
Sources
Find companies offering this service
Last updated 2026-10-24