Sizing sawn timber

[Paul in the woods]

Can someone give me a rough idea about sizing a sawn plank of fresh wood if I know the planed dimensions I need when it's seasoned?

 

From past experience I know if I order 20mm planks some might be about 18mm, then there's shrinkage and an allowance for warping.

 

I'm after a finished size of 18mm x 225mm planks of western red cedar and possibly larch. Would ordering 25mm x 250mm sawn be sensible?

[Forest2Furniture]

On that sort of width if you've got a badly cupped board you'll be lucky to get 15mm finished thickness from a 25mm start.

 

Your best bet is to go to the yard and sort it yourself.

 

Are you buying green or air/kiln dried?

[Paul in the woods]

I'm ordering stuff cut to size from green logs, so no option to sort through. I also plan to order a large amount and as I only need some of it to be planed down to an exact size I can sort through the stack when seasoned.

 

I ordered some 150mm x 28mm green larch planks from the same place a few years ago and they've only cupped by about 2mm.