Is there a general rule of thumb to calculate lumber needs for a project?
For example if door rail and stiles calculate to 28 ft2, can one typical add
say 10% to cover cutoff, short sizes and waste.? I did not include screwups
as for me Id need to buy 2x.
thanks for the tips
It might depend of you hand select the lumber. If you can pick lumber
with your cut list in mind some defect might be ok. If you get a bunch
of board with defects in bad places you may have more waste. If you get
28 board feet of lumber but all the wood is 5.5" wide when you need
stuff at 3.5" then you have a fair bit of waste.
Really depends upon whether you do your own milling or not (buy rough
lumber, SxS, etc instead of dimensioned).
That said, 20% waste is not an unrealistic average for most projects
regardless of how you buy your wood. What will really help keep the number
down, besides a good, workable, well thought out plan, is a cutlist program
like CutList Plus:
It also has some benefit in optimizing your cuts to keep waste down,
although this works better with sheet goods than it does with hardwood
lumber if you don't have much experience selecting stock ... what can really
eat up hardwood inventory is the necessity to do glue-ups and grain
For my own projects I don't need to figure too much more than 10%
since I'll pick what I need. On the job however it's a different
story. We always add about 20% for hardwood stock and depending on
where it comes from we might add as much as 50%.
One time I had a builder bitch at me about ordering too much stock. He
gets credited back from the supplier but his first trim invoice was
getting up there. We were about finished with the job and I asked
him to go into the garage and see if there was any stock left out
there that he thought we could use. There wasn't. The next house we
were ordering stock from the millwork. I was happier than he was!
You might want to invest in an inexpensive optimization program like Cut
List Plus to help you determine the best sized boards to buy to get the most
yield from a board. It will also tell you how much wood to buy.
I use a 20% scrap figure for pricing. That is figured if you can pull
your stock from a large quantity and get good cuts. If you are buying
just enough boards I would always buy 50% extra and assume you'll have
about 20% left over or 30% scrap.
If you are using a figured wood and want to select faces then assume
50% scrap or if you are using cherry or other materials with white
wood and you want to use all heart.
As a hobbyist I have two different methods for waste calculations. If
the lumber purchase is coming out of my pocket money I'll figure in
about 10%. If the lumber purchase is coming out of the general house
funds I'll try to get away with as much allowance as possible. I
usually start out at about 100% overage and working my way down from
there as needed.
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