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Re: Design References for Complex Light Wood Framed Roof

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Tripp,
 
I don't have any good references for you but I can recommend some things that may help when doing your drawings.
 
It can be very difficult to clearly convey necessary information such as posts in the ceiling area. What I do, say for a two story house with a high roof and a low roof is to break out roof framing and ceiling framing plans separate. Starting from the top, I have a high roof framing plan, then upper floor ceiling plan. Then I have Low roof Framing plan combined with an architectural only second floor plan. I do this because typically, the low roof intersects the upper floor two to three feet above the second floor line. Then I have an upper floor framing plan combined with the lower floor ceiling plan. Then I have a lower floor and foundation plan combined. Then I have a separate sheet for shearwalls and hold-downs. It turns out to be quite a number of sheets, but paper is cheap relative to a house built at about 250-350 a square foot (At least in the bay area - and I'm not talking about a luxury home neither). I also developed different symbols for posts to designate whether or not they are continuous through the ceiling or floors or if they stop on top of a ceiling/floor beam. Lastly, make sure you show your double joists/floor beams under walls/posts so they don't sit your posts on plywood.
 
You are right, it gets complicated real fast, engineered lumber is common and steel as well. The architect generally is open to hearing some options and will likely explain the options to the home owner (custom homes only), but generally with a house, the homeowner wants their design as is and these big members are necessary to make the numbers work.
 
Hope that helps,
 
-gerard
Santa Clara, CA
----- Original Message -----
Sent: Tuesday, March 19, 2002 6:26 AM
Subject: Design References for Complex Light Wood Framed Roof

I'm in an IBC high wind region here in Savannah GA.  The local authorities have mandated that all new residential construction with roof slopes of 7:12 and greater require plans stamped by a registered engineer or architect in order to get a building permit.  We do very little light framed residential construction in our office, but for certain big clients we need to be able to provide that service.

The biggest problem I'm having is with the roof framing.  It seems nobody around here wants a nice simple gabled roof-line.  They want hipped ends every where, big dormers, high pitches (10:12), and of course, they want lots of open floor and attic space.  The only way I can seem to make most of this work is to put a bunch of LVL/PSL beams in the ceiling plane and build up short knee-walls or posts to support the ends of all the hip/valley beams and really long joists.  It can get real complicated real quick.  I would use metal-plate-connected wood trusses but that wouldn't give me the attic space everyone wants.

Does anyone know of any good references on the design of this type of roof system?  Also, could anyone point me to some example construction plans that show how to communicate all the ceiling joists and rafter arrangements?  Any pointers you have would be greatly appreciated.

Thanks,

Tripp Howard

 



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