I would venture to guess that SIP manufacturers are contacted after a project has already been designed and now they are constricted to fabricate panels for an “existing structure”. Although, as a structural engineer, I am somewhat skeptical about a SIP’s capability of supporting larger concentrated loads, I do believe that the advantages far outweigh the disadvantages.
Many tests and studies have been done to compare homes constructed with SIPs to stick-framed homes. Energy efficiency, air quality, reduced time and labor costs, manufacturing accuracy and reduced material wastes are some of the advantages of using SIPs.
But one key thing to consider is how SIPs integrate with the rest of the structure, particularly the structural framing system. Not to generalize, but from what I’ve seen, the majority of engineers have little to no experience in the field. Sure, any engineer can size a beam and most can even design an adequate connection. But how many times have we seen a set of structural plans where thigs just don’t work? I have encountered too many issues such as steel beams sticking out of the roof or joists meant to hang into a beam that is at a different elevation. The list goes on.
So why would this be any different for SIP construction?
In my opinion, two of the most important aspects of SIP design are value engineering and material optimization. A 10” roof SIP can span farther than an 8” roof SIP, but how will this affect the sizing and spacing of the rafters? As a structural engineer as well as a timber framer, my knowledge and field experience allows me to look at the whole structure and evaluate member sizes and layout for both the frame & the SIPS, consequently using less material and directly reducing costs. Furthermore, SIP connections are somewhat unique. So, it’s critical to consider how the structure is framed to support the most economical SIP connection to reduce labor costs.
In summary, timber frame & sip construction takes a collaborative effort between the architect, designer, engineer, timber framer & SIP manufacturer to create and coordinate the integration between the building envelope and the framing of the structure. Though I am not an architect, I have designed & engineered dozens of timber structures within Structural Resources, Inc. Combine this with the timber fabrication by Kenai Timber Frames and the close to 30 years of experience I have in the construction industry, the relationships I’ve built with SIP manufacturers has been quite seamless, as I’ve come to understand their thought process.