Reply by Madmark2

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Posted on Is there a standard sequence for writing measurements ?

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1806 posts in 1499 days

#1 posted 09-26-2020 12:58 AM

I order 5 8’ 2×4s on the materials notation.

Different things have different units.

Rough lumber thickness is in quarters: 4/4, 6/4, 8/4. Board feet is always based on the rough dimension. Widths are usually multiples of 2”.

Finished lumber is given as nominals, 2×4, 2×8, etc. But it is known that the actual dims are 1-1/2” x 3-1/2”. The nominal dim can be used for bf calculations but the actual dims cannot.

Build drawings have the final dims: 5/8” x 3-3/8” x 17-1/2”.

Doors are measured by feet and inches so a 32” wide door is 2-8 (pronounced “two-eight”)

A 36” door is 3-0 (three-oh) and this causes endless confusion as folx think “three-oh” means 30” – which it doesn’t.

Rough and finish lumber tend to have the length as the first digits because that’s how lumber yards sort, by length.

Final dims are generally listed by thickness first, again because this is how stock is sorted.

There are no absolute rules. In England they call a 2×4 a “four by two”. Both are correct.

Board feet math is easy in your head if you know the trick. None of this multiply the inches and divide by 144 crap. Memorize this:

  • 2” = 1/6 board feet per lineal foot
  • 3” = 1/4 bf per lf
  • 4” = 1/3 bf per lf
  • 6” = 1/2 bf per lf
  • 8” = 2/3 bf per lf
  • 10” = 5/6 bf per lf
  • 12” = 1 bf per lf

So an 8’ 2×4 is 2×1/3 bf/lf or 2/3 bf per 8 lf = 16/3 bf or 5 1/3 bf.

A 8’ 1×6 = 8×1/2 bf/lf or 4bf.

A monster beam that is 12’ 4×8 = 4×2/3 bf/lf or 8/3 bf/lf x 12 lf = 96/3 bf or 32bf

It seems complicated but in practice you can measure bf and closely estimate costs in your head faster than the counterman can enter it into the calculator.

-- The hump with the stump and the pump!

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