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Re: Glulam roof girders

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On 11/19/06, Will Haynes <gtg740p(--nospam--at)gmail.com > wrote:
On a sloped roof using glulam girders (the girders are running perpendicular to the slope, 2x joists running parallel with the slope) how is the roof sheathing normally attached to the glulams? Are the glulams actually rotated so the sloped sheathing sits flat on the top lamination or is the top of the glulam cut at the same angle as the slope?   I would think it would be difficult to erect if all the girders had to be rotated.
 
I made a quick sketch to show what I mean:
 
http://i135.photobucket.com/albums/q141/haynewp/GL.jpg
 
 
 
Will Haynes


Will-

Sorry for lateness of this reply...drafted it & got busy over the weekend so it has stuff that other posters have mentioned (that I was too lazy to edit out)

How much of an issue this is depends on the roof slope.   I would not  want to rotate all the glulams, that would complicate as sorts of details / connections plus you'd consider a reduction of the moment of inertia & lateral stability

I just got through dealing with this issue on a very small scale.....a 1:12 (~5deg) closed patio cover / roof framed with 6x timber (the sheathing drop across 6 inches is ~.5 inch)

I just bumped up the joist 1/2" proud uphill & let the 3/4" plywood span unsupported the 6" header.

Consider bumping the joist hanges proud on the uphill side & flush on the downhill side...just let the sheathing span the glulam, the sheathing can easily do this.  The size of the "gap" is a function of roof slope & girder width

If you must have  complete bearing at the glulams, tapered furring strips could be spec'd but is it really necessary &  worth it?  

I suppose you could get a custom glulam witih a tapered top cord.  But milling a  "tapered adapter member" & field nailing to the glullams is probably quicker & cheaper.

What kind of slope are we talking about here?


Additonally the joist hangers & the joists do not mate up quite nicely in this type of layout;

unless the ends of the joists are taper cut you'll have "line contact" between the hangers & joists.  :(

cheers
Bob