palletdesign.ai

Glossary

Green lumber

Also called: green wood, unseasoned lumber

Reviewed

Definition

Green lumber is freshly sawn wood that has not been dried, with moisture content above the fiber saturation point of about 28%. Many hardwood pallets are built green: a GMA-style 48x40 in green mixed hardwood weighs about 59 lb, versus about 37 lb once it dries to 12%.

On this page
  1. What green means on a pallet spec
  2. What happens as it dries
  3. When green is acceptable

What green means on a pallet spec

PDS records moisture content at manufacture, and "Green" is a common entry for hardwood pallets built from fresh cants. Green wood is heavier, slightly weaker and will shrink as it dries.

Species lb per board foot, green kiln dried
Mixed hardwood 4.37 2.91
Oak 5.25 3.90
Southern yellow pine 4.45 3.40
SPF 3.24 2.30

These are the weight factors palletdesign.ai uses, including nails.

What happens as it dries

  • Shrinkage: about 1% of dimension for every 5% drop in moisture content below about 28%. A 5-1/2 in board loses about 1/8 in drying to 19%.
  • Strength: stiffness and strength increase as wood dries.
  • Nails: smooth-shank nails driven into green wood that then dries lose most of their withdrawal resistance (the Uniform Standard applies a 0.25 factor), which is one reason threaded nails dominate.
  • Mold: green pallets in closed containers or humid storage can mold.

When green is acceptable

Domestic, short-cycle use is typical. For containers, some buyers set limits: Costco requires moisture content under 19% for containerized shipments. See moisture content and kiln-dried lumber.

Questions

Are green pallets bad?
Not for most domestic uses, but they are heavier, shrink as they dry and can mold in closed containers. Specify kiln-dried when moisture matters.

Sources