I live in Houston Texas. Bought a 30 year old house with 2 inches of attic insulation. I am going to have 12-18 inches applied in about a month. I want to apply a radiant barrier to the underside of my rafters prior to the addition of the horizontal insulation. I am having trouble finding retailers in the area. Do you know of any ? Is "silvercoat solarguard" a worthy product ?