Proper Girder Sizing

Hello guys could you help me with some information on girder/ beam sizing, spanning and so forth. Thanks JMAC

This is going to be good :sunglasses:

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Deck or floor?
Plenty of charts and calculators online such as: Span Tables - Calculate Joist, Rafter and Wood Beam Spans .

Are you asking for guidance on building, or for inspecting?
If the latter, its beyond SOP but still good to know.
If I see seriously deficient structure, I’ll call it out without referencing codes.
If a builder or contractor or seller tries to push back, it is good to know the codes so you can stand your ground.


Thanks Bert, I was looking for inspecting and building knowledge. I agree with your reply as it goes along with the interNACHI teachings, you should know the code in your jurisdiction to call out defects but not to quote code unless you are a code inspector. Got it.

I searched interNACHI for a spanning chart and could only come up with joist spanning. I was hoping that interNACHI had a beam spanning chart to keep my information consistent.

Found this site…

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All generic charts have stipulated in the fine print what loads were used to develop the charts. Most beam applications are unique making the charts useless. For a beam to be adequate it has to pass shear, bending and deflection requirements. Cranking out the math isn’t too hard, but determining the actual loading can be difficult. You can’t design a beam without checking supports at each end including following the load path to the ground to see if you need to install a footing. In addition you have to design the connection from the beam to the column and from the column to the footing.


Thanks Randy, this make sense to why there is so much information out there. I was looking into some local code on beams and was going to use this information as a guide to call out defects, according to safe building practices. I would not want to waste a P.E.s time or the clients money with a mistaken defect. The use of a level can be useful, associated with the knowledge of proper building practictics, I believe you can have confidence with reported conditions good or bad.

Hey Stuart this information is great, I have shared a link to the Canadian version for us in the great white north!

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