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).
Silicone coatings are typically produced by adding a catalyst and solvents to a silicone base. Because the silicone is a natural material, these coatings are bio-degradable. They can be applied to a roofing system using many different techniques, including spraying or rolling. Silicone coatings are available in many colors, including reflective white and translucent. https://youtube.com/watch?v=ggLAUsiuI_o
My other question was gonna be this. We ripped all the drywall out after Hurricane Harvey and we found some latent termite damage from some time back. One of the common studs in one corner is pretty well eaten to shreds. I was gonna brace it but then I read about more modern framing practices and I read how each stud is a thermal bridge. So now I'm thinking that I won't bother with it because the house hasn't fallen down and the foam might help a little. Unless you say to brace the stud. Then I'll do it, Martin! :)
It also has a great waterproofing ability that can shield the roof’s membrane from water and moisture damage. You can also count on the liquid roof coating for its outstanding performance for a wide range of applications and uses. This product can be used at tears and seams as well as in sealing air conditioners and venting systems and anywhere else where rubberized coating is needed.
Spray Foam Insulation
Closed-cell (aka two-pound foam) is denser than open-cell at about 2 pounds per cubic foot. Its R-Value is between 6-6.5 per inch. As a result, this kind of foam is much more expensive than its counterpart. The reason closed-cell doesn't need a vapor retarder is because it already has one. It's permeance is 0.8 perm, which means it can handle cold climates without the use of an additional board or drywall. Closed-cell uses hydroflurocarbons (HFCs) as part of its makeup. However, this material has been known to have a high global warming effect. If you want a green insulation solution, this is not the material to use. A way to avoid this and still use closed-cell is by installing it alongside fiberglass batts.
Spray foam insulation is a great product. Homes insulated with it can be some of the most efficient and comfortable homes built. I've been in plenty of these homes and can tell you that when spray foam is installed properly, they outperform 99% of fiberglass batt-insulated, stick-built homes. (I can also tell you that 73% of all statistics are made up on the spot, so please don't ask for documentation of that statistic.) http://youtube.com/v/ggLAUsiuI_o?version=3
There are several types of reflective roof coatings that impart varied reflectance rates/ values. Typically, the reflective coatings are what are commonly referred to as white coatings and there are also aluminum coatings typically used with asphalt. Highly reflective white roof coatings are typically comprised of acrylics, urethanes, silicones, SBS, SEBS, and other types.
Spray Foam Crawl Space
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.
I did a LOT of prep before using this product. Cleaned, vacuumed, installed additional insulation etc etc etc. This spray foam was easy to work with, and did it's job as it was supposed to. If you are curious, this kit was purchased because - every "foam insulation company" I contacted either did not call back (due to no interest) OR this was too small of a job. That is why I went DIY on this one, that and: I was advised by one of these companies that they have a minimum $2k job because ... (insert your answer here, but I will choose that everyone needs to eat).