Glulam Beam (less than 12" deep) allowable stress 1

[SacreBleu]

Normally, we specify 24F-V4 for ss beams and 24F-V8 for cantilever/continuous.
Lately, I have been getting some feedback that "column-rated" Glulams have been installed as beams (we had calculated various 3-1/8" x 9" deep and 5-1/8" x 9" deep beams, to fit within 2x10 floor joists). The builder claims that all Glulam less than 12" deep is available only as "column-rated" laminations, and therefore it was our "error".
Has this been noted by anyone? The combination symbol may be as low as 16F for the under 12" deep glulams.

 

[HeberPE]

That is certainly the contractor's error, not yours! If the beams were specified as noted, then it's his responsibility to verify what he gets from the lumber yard. I have not had any problem with 24F-V4 glulams being available in any of those sizes. We specify them all the time. You might find it helpful to call some local lumber yards and ask them what they carry "in stock" and what sizes are "special order." I've found it very helpful over the years to keep a current list of "in stock" beam sizes, Simpson hardware, sheathing thicknesses, etc that are readily available.

 

[RARWOOD]

You correctly specfied the material. 24F-V4 & 24F-V8 for Douglas Fir and 24F-V3 for Southern Pine are probably the most readily available glulam stress combinations in the U.S. These combinations apply down to a minimum of 6". The firm that I work for, stocks 3 1/8 x 6 and 5 1/8 x6 in 24F-V4 Douglas Fir.

What may have happened is that the contractor's supplier didn't stock 9" material so he ripped down deeper stock. If you took a 5 1/8 x 18 Douglas Fir glulam and cut two 9" nominal pieces out of it you would no longer have an allowable bending stress of 2400 psi.

The center of the 18" glulam would be made up of L3 laminations. It would be safe to use the design values for Douglas Fir combination #1 which is glued up using all L3 laminations.

Richard's Rule: It is always available but not at the price the contractor wishes to pay.

 

[SacreBleu]

RARWSC,
Sounds like that's what happened. Thanks!