I need some help / advice on the following, Please. You would think I would now the answer, but I don't.....

My house roof plan has a couple flat shed dormers with 4/12 slope and I'm wondering how the connection to the upper main roof, 8/12 slope, is accomplished without a supporting beam under the connection ?

I also, will have a couple large gable end wall dormers with ~12' long valleys. The ridge will have a beam under it to give support but there will not be any beams under the valleys. Once again, I'm wondering how the valley connection is accomplished without beam support ?

For what it's worth I asked the above questions to 2 different National Brand SIP Representatives and they both said the information was proprietary to each job. However, they would be able to provide the answer once I entered into an agreement with them. 


Being a retired GC I feel this is BS. The books they all freely hand out to customers include showing panel connections at corners, sill and top wall plate among others but do not show what I'm needing. What gives ?

Also I will have a high snow load requirement of 90-100 lbs per sq. ft. @9600 ft elevation in the Rockies of Colorado.

Thanks in advance.

 
 

Retired1

There may be other methods to support the ridge of the roof, but the three I’m most aware of are a ridge beam, center wall or trusses. I did help assemble a SIP house in Fairplay, which was also at 9600 ft, that had a center wall under the roof ridge that had windows, and had a flat shed roof under the windows, so an interior wall supported the ridge of the higher roof, and the lower roof was supported by a ledger board attached to the center wall. Depending on the size of the dormer, sometimes it’s possible to assemble the dormer, and just set it on the roof.
I also think that the two reps you talked to were maybe just salesmen, and not really assembly experienced. Normally when I’m asked for an estimate, I have an engineer look the plans over and determine what will be needed for the proper support of the structure, and include the cost of the needed beams and lumber in the estimate. And, like you, living in the Rockies at 8600 ft, I’m pretty aware of the challenges of building in the mountains.

Steve
GrandCountySIPs.com

retired 1;

there isn't a generic detail for all jobs, they need to be site specific. I don't blame a mfg. not to give a detail for a project they are not doing, pick a supplier then you will get the connection details,  you don't need it before then anyway?

retired1,

I'm assuming your dormers do not spring from the main roof ridge. Having a beam for the dormer roof to rest on is simplest. Without the beam, double triple or even quadrupled splines would have to be used around the main roof opening.

Given your extreme snow loads I recommend an engineer look at your project.