The answer to the question of which attic insulation is best is, of course, entirely circumstantial. When the design of your attic allows, the best attic insulation is inexpensive, easy to install and will yield the performance you're looking for.
As a builder in the hot and humid South, I regularly use spray foam in my houses. Spray foam makes it much easier to encapsulate my attic (where most HVAC systems in Texas live) so that my ducts are inside the thermal envelope.
When you hear about a deep energy retrofit project most people think of the snowy North Eastern US. I can tell you that the strategy for a Northern remodel with energy efficiency in mind is very different that our strategy for Hot/Humid Texas. In this video I'll show you 6 things we are doing to making a dramatic difference in this 1950's slab on grade house's energy bills.
The roof is on, and insulation contractors are now advising Ted Storm on how much open-cell foam to spray on the back side of the roof deck. Three contractors suggest the same thing, but is their advice on the right track?