From BUILDER sibling JLC Online comes this report on how structural insulation can improve the integrity of the building envelope.
On a recent build, Matt Risinger leaned on the adhesive capacity of two-part, closed-cell polyurethane foam to provide increased racking resistance to the frame walls and uplift resistance and waterproofing to the framed roof.
Risinger is on solid ground when he claims that closed-cell foam can increase the structural capacity of wood framing. The basis for the structural properties of closed-cell spray foam stems from research conducted at the University of Florida, led by Professor David O. Prevatt, a P.E. and Ph.D. who is an expert in wind engineering.
JLC reported on Prevatt's early work in 2008 and followed up in 2013 with a report on a number of studies led by Dr. Prevatt. This work found that closed-cell spray foam can double or triple the strength of a wood-frame assembly and improve a building's performance against high winds. The research examined three application types, including the "fillet" (or what Matt called "picture framing" the building cavity) and a 1-inch-thick application suitable for the "flash and batt" method that Matt uses.
