Ever use an insulation strategy called flash and batt? In this video, Matt Risinger, master builder, discusses the strategy. The flash portion is the closed cell foam used on the outside of the house. The insulation job is finished off and the batt portion is used. There are advantages to this strategy that provides two different insulation products, spray polyurethane foam and then a traditional batt on the inside. The reason for the combination is that the spray polyurethane foam is a great air sealer and adds structural integrity to the house, but it's a pretty pricey endeavor, especially closed-cell, which is the most expensive insulation you can use.on your house and beyond the ½-inch depth, there may or may not sufficient benefit of to filling the cavity with closed-cell. Instead, they finished the cavity with a traditional bat product, in this case, stone wool. Made from volcanic rock and slag left over from steelmaking, the combo does not burn, off-gas, smoke or ignite. Where there is exposed foam in the attic, it will be sprayed with a coating to prevent fire ignition. Another benefit of stone wall insulation is soundproofing. By using the insulation not only on the outside of the house, but also throughout interior house, plus using 5/8" sheetrock on the whole house, sound transfer is minimized. Check out the video and learn all of the benefits to adding flash and batt insulation to your builds.