I don't know if it's common or uncommon, but installing a layer of rigid foam above your roof sheathing in order to interrupt thermal bridging is always a good idea, and is preferable in all respects to a roof assembly without any rigid foam above the sheathing. If you decide to install rigid foam above the roof sheathing, you shouldn't use closed-cell spray foam under the sheathing; either use open-cell spray foam (which is vapor-permeable) or a fluffy insulation like cellulose, mineral wool, or fiberglass (any of which will allow the roof sheathing to dry to the interior).

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).

Roof leak repairs with roof coatings are often made after the damage has been done. However, you can avoid roof leaks and unnecessary damage altogether if you keep up on routine roof maintenance. A surprising 65 percent of roof replacements are performed because of roof leaks. Leak repair is a top priority among building owners and managers. Break the roof-repair cycle with liquid EPDM Roof Coatings. Liquid Rubber has also formulated custom EPDM Coatings and EPDM Rubber Coatings for your specific commercial and industrial needs. Liquid Roof and Liquid Rubber are liquid EPDM products for leaks repair that form a membrane of 100% pure EPDM rubber when cured. This rubber coating is specially formulated for roof repair and leaks repair. EPDM rubber coatings can be widely used for commercial purposes.

Spray Foam

Liquid Rubber is generally fine when applied in one coat at a 20 mil film (42 sq ft per gallon) thickness and will still withstand extremes. That is the beauty of the EPDM polymer. A second coat would provide insurance where exposures are likely to be very extreme. Radical extremes in temperature where constant surface temperatures reach 250°F or above or -20°F or below. Warning, though, if the second coat is applied at the wrong time, it may create cracking, fissures or bubbling. The second coat should be applied either when the first coat is still tacky or when that first coat has had a chance to fully cure (up to 3 months.)

Demilec, a company located in Texas, has invented a type of insulation foam that can help all of the cracks and uneven pavement problems. Geolift can help to lift existing concrete surfaces and fix those problem areas around your house with much less labor. Geolift works for driveways, sidewalks, patios, garage floors, even pool decks. And yes, it is a foam, just like your beloved spray foam!
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?
Typical roof coating dry film thickness vary from paint film thickness (plus or minus 3 dry mils) to more than 40 dry mils. This means a roof coating actually becomes the top layer of a composite roof membrane and underlying system. As such, the roof coating is the topmost layer of protection for the membrane, receiving the impact of sunlight (both infrared and ultraviolet (UV), rain, hail and physical damage.
I recently did a remodel project for my basement using spray foam insulation. The original builder has used fiberglass, but I wanted the best insulation i could find. We chose closed cell foam because it blocks moisture from getting into the house. It took one day to install and was fumey for about 3 hours. It was pretty cool watching it being done. It comes out as a liquid and then expands rapidly into a foam. It's quick! Then they took a types of saw to shave it flat with the wall studs so we could then go ahead and drywall. https://youtube.com/watch?v=ggLAUsiuI_o
Additions & RemodelsAppliancesArchitects & EngineersBathroomsCabinets & CountertopsCarpentryCarpetCleaning & Maid ServiceConcrete, Brick & StoneDecks & PorchesDriveways, Patios & WalksDrywall & InsulationElectrical & ComputersFencesFlooring & HardwoodGarages, Doors, OpenersHandyman ServicesHeating & CoolingKitchensLandscapeLawncare & SprinklersPainting & StainingPlumbingRemodelsRoofing & GuttersSidingSwimming Pools & SpasTile & StoneWalls & CeilingsWindows & Doors

How Much Is Spray Foam Insulation Installation

Loctite TITE FOAM Window and Door is a Loctite TITE FOAM Window and Door is a new generation of polyurethane-based insulating foam sealant that expands to fill seal and insulate around window and door jambs. Loctite TITE FOAM is a minimal-expanding foam based on purified and concentrated ingredients that provides four times more density versus conventional window and ...  More + Product Details Close
Most closed-cell spray foam is now formed using hydrofluorocarbon (HFC) blowing agents that have high global warming potential, partially or completely offsetting the climate benefits of the energy savings they can offer. In the United States, HFCs are scheduled to be phased out by January, 2021. A few spray foam suppliers have started supplying spray foam blown with hydrofluoroolefin (HFO) blowing agents without this problem as of early 2017.[14]

Roof Coating