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Structural Insulation

Insulation can add both strength and resilience to face the worst mother nature might unleash. In this video, Matt Risinger, master builder, discusses strategy that will deal with both mother nature and with ensuring a house lasts for generations rather than just decades. The basis of the strategy is closed-cell spray polyurethane foam. There are two main types of spray polyurethane foam, open cell foam and closed cell foam. Because this one is closed, it's very rigid and has a lot of strength. This same foam is used in Yeti coolers. It also has other characteristics. It has the same chemistry as polyurethane glue such as Gorilla Glue. When the foam is sprayed into a cavity it's two-component foam so there is Part A and A Part B. It combines in a hose at a high temperature of approximately one hundred and thirty degrees when it leaves the gun and it expands. Closed cell foam has more density than open cell foam. This is two-pound foam, a glue that will lock everything together. Use protection including facemasks, cover clothing and bring in outside air to the facemask. In effect, this is airborne glue. When we spray into the cavity that foam is physically adhering and gluing to the sheathing. There is Advantech sheathing on the exterior, and the house has traditional framing. Everything is framed on 24-inch centers and then that polyurethane foam locks everything together, adhering to Advantech, to the sides of the studs and it will deliver between 75% to 200% more strength to the house. At the foundation we've locked the framing down with some really big hardware bolted to the foundation and we have multiple screws into the framing. As we move up, you'll notice the framing also has a lot of strapping and there's a door or a window opening everything's strapped together and at the roof line we have metal rafter ties and a timber lock screw going up through the double top plate into the rafters. The closed cell foam adds a ton of strength and uplift or resistance to the house. It will attach to the top plate to the rafters and the decking. If there are 100 mile-an-hour winds, everything is still locked together. If the job does not have enough money to do a whole-house installation, another option is to picture frame things. Spray with the gun at a 45-degree angle in between the rafter and the decking so that that spray foam will glue so the decking holds together and doesn't blow off and spray the roof seams so that where there are H clips holding the Advantech roof sheeting here apart from each other and if the worst of weather came and part of the roof blew off we won't have all that water intake on the house because of the closed cell foam. Another option is to use a zip sheathing on the roof that has a taped seam. If the underlayment blew off, you'd still have those panels and the tape at the seams to help with water intake. Closed cell foam has a very high R-value of nearly R-7 per inch we've got two inches here. Because we have two inches, there is room inside the cavity for a bat and this is called a flash and bat system. Rockwell bats are R-15 so we're just shy of R-40 in the walls and an R-Value in the roof system of 40. The closed cell foam is an excellent air barrier, so the house is going to be very tight. We're somewhere around 1,200 square feet per ton of air conditioning on this house compared to a traditional house in Texas that may be is five or six or seven hundred square feetClosed cell foam also provides a vapor barrier as long as you spray it an inch thick so that's why you often see the flash and bat method as it won't allow water vapor to condense on the back of your sheathing as the vapor will not permeate through the closed cell foam.