This stuff works GREAT ! I live in an older mobile home that had a lot of leaks when I moved-in. I worked for two years to locate and fix them all. Now I simply go over all of the repaired places once a year just to be sure everything is OK. NO LEAKS FOR 4 YEARS NOW!!  Others here use "sno proof" or something that does not stop leaks. When I tell them about my success, they don't seem to want to pay the$ for this superior product. Too bad!. I used the tape in  repairing the leaks.
Also, I'm wondering... Is this website is being regularly updated? A local installer (in Oct, 2010) in MA quoted over twice the price you list here. "Open cell alone ~$1.35 per sq ft for R-13. Or a 'hybrid method' using 2inch closed cell for R-13 followed by 1.5inch open cell for R-6. Hybrid is $2.85 per sq foot for R-19 rating". Maybe installers are charging higher prices to profit from those trying to meet government energy rebate by Dec 31?
Polyurethane is a closed-cell foam insulation material that initially contains a low-conductivity gas in its cells.[5] As a result of the high thermal resistance of the gas, spray polyurethane insulation typically has an initial R-value around R-3.4 to R-6.7 per inch.[5] In comparison, blown fiberglass typically has an R-Value of only R-3 to R-4 per inch.[6]
The Canadian National Building Code references the CAN/ULC S705.2 National Application Standard which must be followed during all installations of 2lb medium density closed cell polyurethane foam. Every installer of CAN/ULC-S705.1 compliant medium density, spray applied foam must be licensed in order to spray foam and hold valid photo ID issued by their Quality Assurance Program (QAP) provider showing their license is in good standing.
If you cut the nails holding one of the corner studs to the bottom plate and the top plate with a Sawzall, you can use a flat bar (or a flat bar plus a wrecking bar) to pull the stud off the sheathing nails. Either re-use the stud, or buy a new stud, and install the stud with toenails as shown in the link I provided in Comment #51 (this link: Outside corner detail).
If you’re looking for an effective and efficient Elastomeric Roof Coating, you might want to consider the Kool Seal roof coating. This product comes in a 115 fl oz container and is white in color. It is easy to apply and use that it can stick well even in the harshest weather conditions. This product offers maximum clinging to the RV roof despite the temperature. You can also rely on its effectiveness no matter the type of weather.
We live in middle TN and had our house foamed last year. We noticed recently that some of the foam was shrinking and seperating from the floor joists. We contacted the installer and he informed us that the manufacturer had a problem with a batch of foam during the time frame we had our house sprayed. The contractor wasn't sure if we had the recalled batch installed in our house or not. He said he would check the batch numbers and let us know. He seems like a nice guy promising to do whatever it takes to fix any problems. Do we trust him, however, to be truthful about the batch number? Do we have any options for finding out the information ourselves? I inspected the entire crawl space of the house and noticed approximately (5) areas that were seperating and a couple areas where the foam didn't adhere to the block. Do I assume by it being so infrequent that it is nothing to be concerned about? My concern is the walls that are not capable of being visually inspected because of sheetrock.
Before you decide on spray foam or another method of insulation, it's important to understand the superiority of spray foam compared to traditional materials. When compared to fiberglass batts, spray foam offers nearly double the R-value per inch, achieves air-sealing and insulation in one step, won't be damaged by mold or moisture, and won't settle, compress, or otherwise be damaged to the point it needs replacement.

Where Can I Buy Spray Foam Insulation