What 'prescriptive guide'? Do you have a pointer?

As far as size? That is really silly. SIPS are merely an upgrade for stick framing, so to say that there is a limit, is again silly.

What is their criteria for the 'limit'?

JC,

Thanks for replying. SIPS finally have a prescriptive guide published by HUD (just like ICF's). I downloaded and printed the 50 page document from Fischer's SIP website. I am very glad that a guide was finally published. But in the initial few pages they state a design limit of 60x40. I am glad I can build what I want. As far as roof loads I am thinking 50psf.

The download you're referring to is the prescriptive method that is still under review. The final acceptance of the submission will not be know until it goes to a final vote later this Summer.
The specified limitations were chosen as base-line. It doesn't suggest that you can't build anything (size) you want. The process involves recognizing any building material's limitations and submitting the engineering data and testing that support these basic parameters. The ultimate inclusion of SIPs into the ICC will allow building officials to verify the acceptance of SIPs. This acceptance assumes you're building below the base-line. It also means that the vast majority of residential construction would fall within the area of code acceptance. If you want to build bigger and more elaborate, proceed at will. Know that you'll likely need the services of a structural engineer.

As an aside; The nearly five hundred SIPs structures we've built over the last seven years have needed a PE's stamp ONLY 20% of the time.

Al

Al,

Thanks for the reply. I did not realize that the Prescriptive Guide was preliminary. It certainly appeared final. I knew that I would likely need the services of an engineer for an SIP. I am still on the fence between SIPS and ICF. At least from an ICF standpoint, the prescriptive guide is already in second edition.