The problem was that the installer was doing his first spray foam job ever, and the thickness of the insulation varied from zero (visible roof deck) to about 9". Unfortunately, good average thickness doesn't cut it. The coverage needs to be uniform because a lot of heat will go through the under-insulated areas. (See my article on flat or lumpy insulation performance.)
SPF, a spray-applied cellular plastic, is made by mixing chemicals to create foam. Those chemicals react very quickly, expanding on contact to create foam that insulates, air seals and provides a moisture barrier. When properly installed, SPF forms a continuous barrier on walls, around corners and on contoured surfaces. It resists heat transfer very well and is an effective solution for reducing unwanted air infiltration through cracks, seams, and joints. https://www.youtube.com/attribution_link?a=ggLAUsiuI_o&u=%2Fwatch%3Fv%3DXXXXXX%26feature%3Dshare
Where To Spray Foam Insulation
That’s $58.3 Billion dollars. That’s roughly how much money we wasted in 2010 in the US according to the Department of Energy because of air leaking out of our building envelopes. If your building leaks energy, you’re paying more for energy than you need to. Clearly you’re not alone. If you’re ready to claim your share of the savings, it’s quicker and easier than you think.