used lumber opportunity

[FrankInWI]

ad in newspaper is for "thousands and thousands of used douglas fir 2 X 6s".  (14')  Could I double these up and use them for my floor joists on my ~240 sq ft shed / cabana?    

[Dberry]

2x6 DF can span 9-10 feet on 12" center depending on quality.  Doubling up doesn't increase the span by much.  (inches).    If your cabin is less than 10 feet wide, you can probably get away with it.  If you can get a good price on it it might be a good deal even if you don't use it as floor joists.  All it takes is a beam down the center of a cabin to make them a viable choice...  or even as flooring or rafters.

[n74tg]

Put a girder down the middle; then you can double the span to 18-20.  

[bil2054]

Gee, Frank, that's just what I would jump on for studs, etc.
If the price is right and they're not too used there's thousands and thousands of uses for 'em. [smiley=wink.gif]

[FrankInWI]

yeh, your right, if the price is great there are many uses. It says the nails are cut, so the ends should be ok too.  When I asked about using them for floor joist by doubling them, I neglected to add that the floor is going accross two beams which are the base on the ground (for later movement).  
I was real surprised that an earlier reply said that doubling only adds a few INCHES to the suitable span.  Intuitively, that seems impossible.  Going from 2 X 6 to 4 X 6 would seem to make a dramatic difference.  

[glenn-k]

From The Ground Up -- Charlie Wing, gives 9'5" single 2x6   13'4" for a 4x6 with rough sawn lumber at 45 lbs psf 5 lb dead load 40 lbs live load 4" centers 1000 psi fiber stress.  I'm not sure if a double 2x6 compares exactly as a 4x6 - seems it should . another way putting 2x6 on 12" centers verifies it does 13'4" that way also.

Going to 2x12 - same board feet but deeper makes the dramatic difference --- 18'10"

[bartholomew]

As a rule of thumb I'd assume that if you are doubling up the joists then each is bearing half the load.* So instead of looking at the 40 psf live/10 psf dead load chart, go by the 20 psf live/10 psf dead load chart. The one at http://www.wclib.org/pdfs/SimpSpanTbls.pdf doesn't include 12" spacing for the 20 psf live, but looking at the 16" and 24" spacings suggests that doubling up will add about 2'3" to the 2x6 DF span, or about 13' if No. 2 quality. You can also look at the 24" spacing in the 10 psf live/5 psf dead load chart (a quarter the spacing, a quarter the live load), which suggests that No. 2 DF would span 13'6". Note however that this is unlikely be acceptable to a building inspector.


* This approach can be validated by comparing the 20 psf live loaded 24" spacing to the 40 psf live loaded 12" spacing (i.e. double the joists, double the live load). The spans are nearly identical for all species of  No. 2 and better 2x6.

[mark_chenail]

Just to be nosey. Whats the asking price on that and how many are there exactly. If its literally thousands you could easily frame the whole house with them and use them as floor boards as well.  Those 2x6 would be fine with a girder under neath and some blocking and a solid 2x6 floor would be very stable.  The rafters on all my pole buildings are 2x6's.  Shame they arent in Missouri, my newneighbors could use them for the house they are about to start building in two weeks.