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Re: WOOD: "Engineered Wood Costs"

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The answer is, yes, engineered lumber is much more expensive. The rafter in question is about right, $2-$3 per board foot is what I'm used to seeing. This is about 4 times a S Pine No2 member at 50-65c/BF. When I designed a vaulted section for my own house, and found out what a 3.5x16 PSL ridge beam would cost, I though I'd just get it as a timber section in WRC. At the time the cost for WRC was about 1.75-2.00/BF, similar to the PSL. That was a great idea until I got a member size somewhere in the 10x24 range. All of a sudden, it was not economical.

I use the spacing trick in Sizer to check doubled rafters and haven't had problems. (Actually, I have to use lots of tricks to get Sizer to give me the output I really want sometimes).

BTW - where is this guy going to get 28-30' 2x12s (26' span plus ridge cut and tail)? Maybe he was planning on using a pair of 16' 2x12s with a Simpson Mending Plate in the center?

At 08:43 AM 11/9/2004 -0600, you wrote:
ALL:

Thanks for the responses so far.

I wrote before I had gone back in to my calculations to figure out what was controlling things. It turns out that the problem is WIND UPLIFT--a fact that you'd think I'd remember since I was discussing it here about that time--too many jobs, not enough brain cells.

One thing I noticed is that Woodworks 2002a, which I am using, does not allow "n-ply" members to be considered when sizing roof joists/rafters. You can "trick it" by halving the spacing, I suppose.

Anyway, I have been able to fiddle with the design parameters (mostly wind uplift) to get a TJI to work. I think the TJI is probably competitive; definitely so if the alternative is putting in a beam, etc.

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