Some foam form manufacturers claim insulating values as high as R-35, with dubious scientific support. The Blue Maxx wall from AAB Building Systems, however, boasts what I think is a more believable R-25. With 21/2 inches of expanded polystyrene on both the inside and outside of a 61/2-inch concrete wall, the Blue Maxx wall will stop everything from cold and bugs to water and sound, according to the manufacturer. The basic block of this system measures 48 inches wide, 17 inches tall, 111/2 inches thick, and weighs under 8 pounds. Other shapes include end caps, 90° corners, and adjustable corners. The blocks fit together like gigantic Legos. X-shaped plastic braces spanning the gap between the two foam sheets project through
