Sonny, tell your idiot engineer to stick to his line of expertise.
There is a ton of information on this phenomenon that started as soon
as sawmills began to sell planed wood. So maybe a couple of hundred
To overly simplify, a board foot is the size of the board BEFORE it
was planed or smoothed. So a 1X6 was a board that began as 1" thick,
and 6" wide. However, to make it convenient, you began to be able to
buy planed boards from the mill. Planing decreased the thickness on
each side and the edges, so the sizes you see now reflect the fact
that the wood has been processed to a consistent size, or its finished
However, the mill still cut it 1"X6" so they would have enough
material on the board to smooth it. You didn't think you would get
that extra material free, right? So you are charged for the board
itself when rough, as well as the convenience of smoothed faces. To
drive that home, go to a real hardwood lumber store (NOT HD) and ask
for a 1X6. They should ask you "nominal (unplaned) or smooth?". If
rough, you can take the board home and plane it yourself. Make to
your own smooth boards to your dimensions using nominally sized
As far as quarters go... think about it. Maybe since it's
Thanksgiving, think of an pie as an inch to visualize it.
With that in mind, think of one quarter of a pie as "a quarter of a
pie". So to extrapolate, if you have one quarter of an inch, then you
have..... wait for it..... here it comes..... one quarter of an inch!
So 4 quarters would be..... one inch!
Five quarters would be..... an inch and a quarter. Eight quarters
would be two inches, etc. Just count the quarters on your tape and
you will have it.
IME, the quarter system of describing wood sizes is used only to
describe thickness of rough (nominal) lumber. It is not used to
determine width. You won't find an lumber man that asks you if you
want 4/4 (four quarters) by 24/4 (24 quarters) by 400/4.
You should also know that unless it is in a specific purpose lumber,
nominal sizes almost always refer to hardwoods, not softwoods.
Some engineers are pretty bright fellows, but this one sounds brand
new. Show him this to help educate him as to how BF is calculated,
and after that DAGS the key words.
Check out the highlighted words in this book, page 216.
"Understanding Wood" (to me) is the absolutely undisputed king of
reference books on all things wood.