I've had concerns with foam in walls with only 2-3" and the resulting air space & convective currents. spray foam for walls is not one of my recommendations to my clients. instead foam sheathing to exterior of walls caulked,taped & sealed. conventional insulation & air tight drywall approach. a better and affordable wall with no extremely long payback like spray foam in walls.  Insulation Spray Coating
The Rubberseal creates a coat that can efficiently reflect heat off the roofs of buildings. It is Energy Star rated, which means it’s friendly to the environment.The spread rate of this product is 60 square feet per gallon at 20 imperial mils. It dries in 2 hours but takes 72 hours to get fully cured. Check the weather forecast before you apply it.

A rule of thumb puts two thirds of the coating on the substrate and one third in the air. True HVLP guns use 8–20 cfm (13.6–34 m3/h), and an industrial compressor with a minimum of 5 horsepower (3.7 kW) output is required. HVLP spray systems are used in the automotive, decorative, marine, architectural coating, furniture finishing, scenic painting, and cosmetic industries. Spray Coating