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1970s Panelized Roof

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I pulled out my 1st Edition (1966) of the AITC Handbook to verify the sizes
of GLBs.  Pre-1971, the standard finished widths of GLB members were:

5 or 5-1/4"

It should also be remembered that pre-1971 thickness of 2" nom. lumber was
1-5/8", therefore the depth of GLBs would be multiples of 1-5/8".

I don't have your original post on this subject on this computer, otherwise I
could give you what the properties for the GLB would be per inch of width.

The 1970 UBC gives allowable stresses for DF-L lamination combinations of A,
B, and C as 2400, 2200, 2000 psi, respectively, E = 1.8 X 10^6 psi.  A
structural firm that I worked for in the early 1960s would design GLBs for
2200 psi and specify 2400 psi.

I have found that getting copies of existing plans is always worth all the
effort that may be required.  Much can be learned, sometimes startling,
reviewing the plans.  I have also found that the facility management
divisions of national or regional chain stores are extremely cost conscious
about maintaining their stores and preserve and protect plans so that they
will not have to go to unnecessary expense in remodeling/repairing their

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

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