What it is called, by market
One concept, four markets. Where a name means something else locally, the card says so rather than leaving you to find out on site.
United Statesyours
Close, not identicallumber
In American usage "timber" tends to mean standing trees or very large sections, not ordinary sawn stock.
Canada
Close, not identicallumber
As the United States, lumber is the everyday word for sawn stock while timber means very large sections or the standing resource.
United Kingdom
Same thingtimber
Australia
Same thingtimber
The governing standard, by market
United States
NDS
Design values and methods for wood construction.
United Kingdom
BS EN 1995 (Eurocode 5)
Design of timber structures.
Australia
AS 1720
Timber structures design.
Calculators for this
Each works in either measurement system, and the terminology on the page follows whichever market you have selected.
Frequently asked questions
- Is a 2x4 the same everywhere?
- No, and this is the entry that changes a quantity rather than a word. A North American 2x4 is a NOMINAL size: the piece is named for its dimensions before drying and planing, and the finished piece is smaller than that in both directions by an amount fixed in the grading rules. British and Australian sawn timber is specified in millimetres, and the figure quoted may be the sawn size or the finished planed size depending on how it is sold — a different convention, not a translation of the same one. So there is no metric equivalent of a 2x4, only a nearest available size; substituting one for the other changes the section's depth, and depth is what governs a joist's stiffness.
- What does timber mean in American usage?
- Usually either standing trees or very large sawn sections, rather than the ordinary sawn stock a British or Australian reader means by the word. In North America the everyday trade term for sawn structural wood is lumber, and "timber" is reserved for heavy sections — the sizes used in post-and-beam and heavy timber framing — and for the forestry sense of the standing resource. So an American specification for timber is usually describing something larger and more specific than a British one using the same word, and it is worth confirming which is meant rather than assuming, because the two readings imply very different members and very different prices.
- Are grading and strength classes comparable?
- Not directly, and this is the second place the words hide a number. North American lumber is graded to rules published by grading agencies, with design values assigned per species group and grade. European and British practice assigns a STRENGTH CLASS — a C or D designation — which bundles the design properties into one label independent of species, so the same class can be met by several species and grades. Australian practice uses its own stress grades. A specification calling for one system's designation cannot be met by picking the nearest-looking label in another: the mapping is a design exercise, and the properties that matter differ between the systems rather than merely being renamed.