Let's stay with this tile-oak thing for a little bit. .....
It is true that I have been discussing how this works with an integrated design; just what is this so-called "integrated design?" The finished product, in this case a house which is the successful outcome of an integrating process, has the major subsystems tied to one another in such a fashion that they all work together efficiently and economically, just the way Mother Nature does it. Hopefully the result is also aesthetically pleasing, just as it always is when Mother does it. In the example above, the tile finish and the slab are "analogous" materials that work extremely well together both structurally and thermally. Where the thickened edge of the slab may also serve as the "foundation," then an additional saving is picked up with this system as well. Of course, much of the initial construction cost saving will be lost when the above ground portion of the building gets enlarged, but then again, maybe it doesn't. Perhaps the garage "attic" is designed to accommodate the function that was originally supposed to go in the cellar.
Whew! This is getting complicated! Well, yes it is, but it is worth the effort because the end product promises so much more. Any additional front-end cost incurred is usually more than offset by significantly lower operating and maintenance costs. Additionally, this kind of building will also build and retain higher value in the market place.
So, how does this play out with SIPs?
SIP structures are fundamentally different from stick structures in two immensely important ways, and these qualities should be fully exploited by the astute designer.
Firstly, SIP structures are "thin shell" structures that work by distributing large point loads throughout their entire surface so that the stress at any one specific location is very low, usually much lower than that which the SIP materials are capable of safely handling. Stick structures collect and distribute loads along the component members, each one of which must be sized or engineered together with its connections to its adjacent members. Conventional stick framing is mostly like post and beam construction, where the beams are analyzed primarily for their resistance to bending, and posts primarily for their resistance to axial compression. SIP walls act more like giant box beams and are capable of spanning very large openings or serving as great cantilevers. Most conventional openings will require no headers in SIP construction. Taking these features all together, a designer should be able to come up with forms and designs that are pretty exciting, or if staying with a traditional stylistic vocabulary, do so at greater savings by eliminating many of the usual large framing members that are a necessity with stick construction.
Secondly, SIPs are their own vapor/air barrier. Stick construction, which has recently been forced to meet modern thermal performance benchmarks, is showing itself to be fraught with inherent problems. The stud bay cavities are excellent places for condensation to occur and all those joints and seams are a devil to properly seal. The time and material that have to be "remedially' applied to a stick structure in order to upgrade its thermal performance to required standards is considerable. They are also difficult, if not impossible, to inspect for compliance in this regard. Here again, the designer may exploit this advantage of SIPs by having conditioned spaces over garages or "the outside" without fear of "drafty" floors. Additionally, buildings with high performance envelopes lend themselves to very different HVAC system strategies that are more economical to install as well as operate.
These are only two ways that SIPs may have a large positive impact on building design, but the most important point remains that SIPs should be seen as a subsystem component -- a very important one, the structure! -- to an integrated design where each component is interdependent on the others.