Is anyone familiar with “Denny Board”? As far as I can tell the company that manufactured it is now defunct and I can’t find any information on it. Closest match I can find is Thermoply. Looks to be foil faced on both sides. Not more than a 1/4″ thick and overlaps at the “butt” joints.   Should this be a concern with walls being able to dry to the exterior during the summer months . I’m in climate zone 3a. Located in OKC, OK.