Tapered Glulam

[shacked]

I am working on a project where the Architect is specifying a 0.5"/ft roof slope with a flat ceiling. Since the underside of the roof joists will be exposed he wants to use 4x12's ripped down to 5" at the ends. The problem is there is a hip and he would like the bottom to be flush. So following NDS guidlines for tapered glulams I have determined that a tapered glulam will work but how is this tapered full length?
Is it ordered custom, or has anyone had any experience with a full length glulam taper in the field?

Thanks

 

[JAE]

You can specify custom tapers in GL Beams. Just check with your local gluelam suppliers.

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[msquared48]

You do not modify glulam beams in the field to create a taper over the length of the beam, only locally at the ends as needed to install. Long tapers are done in the shop.

Also, make sure the 5" deep end can take the shear.

Mike McCann, PE, SE (WA)

 

[shacked]

Great that is what I was asking about.

Thanks

 

[HouseBoy]

I'm curious about the ripped 4x12's.
What grade of lumber are they once you rip them?
Seems like the "visual grading" rules will be affected by this as the defects will then be located nearer to the edges.

Along the same lines.... instead of a glu-lam, would an LVL or PSL beam be workable for the tapered hip? (disregarding aesthetics)

 

[shacked]

The 4x12's are #1. I don't understand your concern as this is a very common procedure with Doug Fir. Besides that the bending & shear stress is so low that I am not concerned about it at all.
Concerning the glulam, yes a psl or lvl would be better but everything is exposes and it would ruin the look.

I should mention that this is not an issue anymore since the owner saw my specifications for 4x12's ripped to 5" and he asked me why I am doing this. I told him that the Architects section through the area shows a flat ceiling and a sloped roof. Also I coordinated this with the Architect. So the owner talks to the Architect and the arch tells him that this is what you agreed upon during the design. So now he wants to use sloped 4x6's and the hip will not be an issue.