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Possible Error on Toolbox Uniformly Loaded Beam calculator

Started by Mattjohndeere2, February 03, 2022, 09:40:01 AM

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Hey all - I was working through some load calcs with the "Uniformly Loaded Simple Beam For Dimensional Lumber 2-4" thick, and I believe there may be an error for Eastern Hemlock design values. When I select Grade #2, the allowable fiberstress is 850, and when I select Grade #1, the fiberstress is 775. Shouldn't those be the other way around? 

Also - It seems the 850 value (assuming that's for grade 1) is quite different from the Manual Entry calculator design value table (1150). I do notice the manual entry design value table states "for timbers 5x5 and larger", maybe that makes the difference, but just wanted to point it out in case it could be an error.

I really appreciate the calculators and I use them all the time, so thanks very much to whoever puts in the work for them (DonP??).

Don P

Ruh-roh, don't trust it till I check. There's a couple of backups if you are sitting here in cold rain wanting do do something. Go to and use their span calc for dimensional lumber 2-4" thick. Hit their publications tab and download WSDD for heavy timber tables laid out by design value. Current design values are in the "Supplement" on that same publications page. (That's also the way to size lumber or beams for an inspector, that stuff is all code referenced)

I'll check back in.

Don P

Excellent catch, thank you. That should be 575 for #2. Give me a bit gotta find the keys to get under the hood and check that array.


DonP, thanks for those resources, and glad I could help!!

Don P

Here we go, Jeff already pm'ed asking if I needed a new way in but we should be good to go. That appeared to be a lone error, I did a real quick scan of the rest of the design values in that array, the patterns looked correct. That was a long day of data entry  :D.

What I've done here in several places where there are a couple of species groups, in this case the supplement lists "Eastern-Hemlock-Balsam Fir" as one group of design values, and then also lists "Eastern Hemlock-Tamarack" as another Group with slightly different design values. I cheated and used the lower design values and gave one option. In this case the only difference is the Balsam group has lower shear values so I used those in the calc. Usually if I'm bumping into whether those differences matter I'm having a basic size problem.

Don P

Just checked the design value list for the manual entry calc. Yes, those are from a different table in the supplement for heavy timber 5x5 and larger (table 4D). Those carry different design values so do make sure you are working from the right table.

I realized how much time I was spending at the kitchen table trying to figure out beams from my trees. When the forum got going I realized I was not alone and there ya go.


Thanks for all your work on those calculators, DonP.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension


Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.


DonP, thanks again. Those AWC pages are a great resource, I didn't know they existed, thanks for pointing them out.

Don P

They are that. For structural solid wood, is the resource. For engineered wood products, plywood, osb, trusses,LVL, glulam, CLT's, etc check out Since those include our typical bracing products take a look at their framing, wind and bracing guides.


Sure is nice to have these resources at our finger tips.
Two LT70s, Nyle L200 kiln, 4 head Pinheiro planer, 30" double surface Cantek planer, Lucas dedicated slabber, Slabmizer, and enough rolling stock and chainsaws to keep it all running.

Don P

I don't think I've said in some time. The calcs here are a little different than most, the "coding" is visible. I was hoping that people who knew more about computers and/or engineering would read the code and keep improving them. So far that hasn't happened, but you never know (especially if I bring it back up  :)). 

but, the quick check I, or any of us, could have done in the moment the other day is... right click>view source. A window should pop up with the "script" the calc is running. You can't modify from there but it is a quick read of the code.