Thread: Standard timber sizes?

In my experience, sizes here are usually imperial, but in metric numbers.

Rough sawn is generally in 300mm (1') increments for length (but sometimes 100mm), 25mm (1") increments in width, and 13mm (1/2") increments in thickness. For dressed timber, subtract 6mm in thickness and up to 10mm in width from nominal rough sizes.

What Elan said. In North America they cut timber in quarter-inch increments for thickness, and refer to it in "quarters", so one-inch thick is designated "4-quarter", 1.25" is "5-quarter" & so on. But here wood is almost universally sawn in half-inch increments for thickness, so if you want a 30mm thick top for your coffee table, for e.g., you'll have to plane down 38mm (1.5") stock. One good thing to come with metrification here is that wood is now sold by its actual thickness - before we went metric it was sold by it's as-sawn thickness, so if you bought "dressed" 1 inch timber it was actually 3/4 of an inch thick, which led to some confusion for neophytes.

The Nth American system is a perfectly logical and useful one, but it can be confusing to folks raised with the metric system (actually, it confused me when I first went there & took me a while to figure out what the heck 'six-quarter lumber' was!). I guess you only need to be aware of the nomenclature if following or borrowing from an American plan....

What he says for widths & lengths applies to normal commercial lumber but wood from 'boutique' mills & suppliers is often in 'slabs' for which the thickness rule will generally apply but widths & lengths may be entirely random. If you want regular sawn pieces from slabs you'll need to expect a good deal of waste. The % waste will depend on the quality of the slab, but you can reckon on around 20% of the nominal surface area as a rule of thumb. That's a very rough rule; depending on the quality & regularity of the slab & depending on what sizes you are chasing, you may get a much higher yield, however, some slabs I've seen for sale at wood shows etc. would be lucky to yield 25% of their surface area as sawn boards!

Cheers,

Anagote in Marrickville and Trend timber at Mulgrave (Windsor) are speciality timber suppliers.
Have a look at what they stock re species and colour to design your piece.

Best thing would be to do a rough free hand sketch and go and have a look at what they have in the rack at this point in time.

What they sell is rough saw not machined so you’ll need a jointer and thicknesser to dress it.
Or a sharp hand plane and some muscle (good luck in this humidity).

They do sell in nominal one inch etc thickness but when you dress it that 25.4mm ends up about 20mm rapidly especially if there’s any twist in the board.
Rough docking to length helps maximise dimension but is slower going.

H.