One thing I wanted to mention was that I think your price point is a little high and that might deter people from considering spray foam. As a project manager for a spray foam company for years I can tell you that we offer 0.5 Lb. open-cell foam at around $.25/board foot. We even offer a 1.0 Lb. open-cell foam for less/the same cost as you quoted the 0.5 Lb. foam for above. The 1/0 Lb. open-cell foam has an R-value of almost 5.
Closed-cell spray insulation, a rigid medium-density material, can be used in exterior applications such as continuous insulation applications, as well as interior applications. This type of foam insulation has a higher R-value per inch making it also suitable for small areas that require the highest possible R-value to meet building code requirements. Closed-cell spray foam’s rigidity help reject bulk water making it a recognized flood-resistant material by FEMA.
The complete line of JM open- and closed-cell spray foam insulation solutions provide superior thermal and energy performance, as well as advanced air, moisture and sound control in any climate. These products can be used in interior and exterior walls, unvented and vented attics, floors, ceilings and crawl spaces. Plus, using spray foam can reduce air leaks and create a more comfortable, energy-efficient home – meaning you could see more energy savings every month. https://www.youtube.com/watch?feature=youtube_gdata&v=ggLAUsiuI_o
In addition, it's difficult for an inexperienced installer to evenly spread the insulation foam over a surface. Miissing spots can leave holes and gaps for cold air to get through. Proceed with this project yourself only if you're doing a small insulation project -- such as installing foam in a crawl space or around your plumbing. Leave larger projects like the attic, basement or garage to the professional insulation contractors. Insulation professionals have the tools, equipment and background knowledge necessary. Moreover, they know how to accurately price insulation, whereas you could inaccurately budget for a DIY project and end up paying significantly more. Don't take the medical, physical or financial risks that come with pursuing this as a DIY project unless you're absolutely certain you have the skills.
Spray Foam Professionals
Acrylic coatings are typically applied in two coats, with the second running perpendicular to the first. 1 gallon per 100 square feet is a good estimate for these coatings, as they do not need to be applied nearly as thick as many other coatings. These coatings can be sprayed or roll-applied. Acrylic coatings generally require a re-coat within 2-3 years of application. http://www.youtube.com/watch?feature=youtube_gdata&v=ggLAUsiuI_o
A. You can use closed-cell spray foam that way if you want, although you should realize that the spray foam will prevent the roof sheathing from drying inward. This approach should only be used if the roof sheathing is bone dry, because it will never dry when sandwiched in this manner. Most building scientists would prefer to see fiberglass rather than closed-cell spray foam under the roof sheathing in this type of assembly.