In short
White wood (whitewood) is sawn spruce or fir. Nordic and European mills grade it by appearance: U/S (unsorted, the best grades mixed), V (fifths) and VI (sixths), with more knots and defects as the grade goes down. KD means kiln dried and S4S means planed on four sides. V and VI are common for formwork and site work; better grades suit joinery.
Grade marks
| Mark | Meaning | Typical use |
|---|---|---|
| U/S | Unsorted: the top grades (I–IV) mixed | Joinery, visible work |
| V | Fifths: more knots and wane allowed | Formwork, framing, general construction |
| VI | Sixths: the economy grade | Formwork, pallets, crating, temporary works |
| KD | Kiln dried to a lower moisture content | Less shrinking and twisting |
| AD | Air dried | Site and packing use |
| S4S | Surfaced four sides (planed) | Joinery, fit-out |
Grade names and limits differ slightly between countries of origin. We state the origin and grade of each lot on your quotation.
Which grade for which job
- Formwork studs, walers and bracing: V or VI, rough sawn.
- Framing and site carpentry: V, KD preferred.
- Joinery and fit-out: U/S or better V, S4S.
- Pallets and crating: VI.
See the white wood sizes page for sections and how to calculate CBM.