As I understand the issue, at some point as a roof design becomes increasingly complex, SIPs adds too much cost to justify.  When is that point reached?  (I bet that there are proper terms for each of these roof styles, but I don't know them.)

A simple gabled roof seems OK.

What of a hip roof?
Does it matter if the panels are factory cut?

What of a roof with two, intersecting roof lines where each is, independently, a simple gabled roof?
Does it make a difference if the ridges on the two intersecting roofs are not at the same level?
Does it matter if one of the surfaces is allowed to be full (without cutting out at the junction)?

What of a stepped roof where each section is a simple gabled roof?



What happens if the design is no longer planar:

A roof made up of curved panels?

What of an "eyebrow" element such as shown in this roof:
http://www.healthyhomeplans.com/home_plans/home_plan_detail.php?plan_id=110

Very respectfully,
Larry

Larry,
I don't think it's a cost issue, as much as it's an assembly and use issue. Of course, the larger the roof, the larger the cost. But as the roof becomes more complex, assembly time & cost to assemble, enter into the equation. And, if the bottom of the panel does not enclose living space, it may not be worth the cost and effort.

SIPS can be used for complex designs. There is no question about that. But please remember they will need to bear on something(usually a beam) so you also have the complexity of getting those beams into position. For any roof, just look at the number of planes, and think about how they will be supported.

PanelCrafters,

Thank you, again.  That makes sense, and it clarifies the problems. 

Very respectfully,
Larry

The appropriate answer to your question about using SIPs for roofs is based on several major issues:

1. The capability of the fabricator - if they have state-of-the-art routers and C & C machines, its not a problem at all to do complex roofs with Hips, Valleys, etc.  We do it all the time and have done extremely complex roof designs with SIPs. 

2. The installer's experience is of major importance: Some roof projects are not for 'beginner's' simply  because they often do not really understand the SIP fabricating process and what is available - in most cases they do not recognize what can be done with a good fabricator and they do not ask the right questions.  As with all good construction, and especially with SIPs, the better-educated and experienced SIP installer will know how to make the roof work with SIPs. 

Experience is a major consideration in building with any altnerative technology and can be greatly assisted if the supplier is also doing the design and engineering, which asssits in the utilization of the SIPs in the building process.

SIPs are only llimited by experience, not technology.

Best of Luck,

Gary Radzat, President
Shell Building Systems, LLC
LINK

Larry,Being down here in Central Fla.as a Green Contractor and building with SIPS for way to many years,the costs overall has beat any other material I have seen in so many ways and yes I have built round houses and roofs with very little waste ,But you need someone that knows the material and how it goes together. Just my 2 cents worth.............................Ralph,.....................link

Larry;

came across this curved eyebrow SIP job Link

A 'curved' roof can be built with SIPs by utilizing 'segmented' panels, which are fabricated to connect like a 'segmented' orange. As long as it can be 'drawn' it can be fabricated and installed - just takes some planning and common sense.

Gary Radzat
Shell Building Systems