Final answer:
The insulation in structural insulated panels is typically smaller than the skin at the top and bottom to fit sill plates and top plates, but the specific measurement is not provided. The R factor is critical in determining insulation performance.
Step-by-step explanation:
In the construction and installation of structural insulated panels (SIPs), a common practice is that the insulation needs to be slightly smaller than the skin at the top and bottom to accommodate sill plates and top plates. The provided information does not specify the exact measurement by which the insulation is smaller; however, it is a standard construction detail that allows for the installation of these wooden members, which serve as a joining surface for other structural elements.
When dealing with insulation performance, it is important to consider the R factor, which is the ratio of the thickness of the insulation (d) to its thermal conductivity (k). A higher R factor indicates better insulation. Typical R factor values for household insulation, like 3.5-inch-thick fiberglass batts, are available as reference points for builders and engineers.