Spray foam comes in two flavors, open cell and closed cell, and provides both parts of the building envelope - the insulation and the air barrier. The building envelope should completely surround the conditioned space, and the insulation needs to be in contact with the air barrier. Since spray foam is both insulation and air barrier, proper alignment of insulation and air barrier is guaranteed.
Open-cell is also known as half-pound foam. It has an R-Value of 3.5-3.6 per inch, and its density is bout 0.5 pounds per cubic food. Low-density foams like these are made partially from raw biological materials Carbon dioxide or water is also used in the makeup. Open-cell uses far less material than closed-cell, but its R-Value is lower. Also, open cell requires a vapor retarder (like gypsum wallboard) and is riskier when used for roof sheathing. It's not highly recommended that you use open-cell insulation if you live in a cold climate unless you have that extra barrier. You should also compare how much money you spend versus how effective the open-cell insulation is wherever it's installed.
We love the Heng’s rubber roof coating because it is versatile enough to work on the RV roof and protects it from the elements longer than other products do. Plus, it is useful enough to be used in sealing seams and tears. Versatility does matter when shopping around for an RV roof coating. It ensures more uses, meaning more value for the money. That said we don’t need to buy a separate product to perform the tasks.