The third configuration of the USA New Wall is the Best wall. Nothing earthshaking or revolutionary in this version. We simply take the two version of the Better wall, the exterior insulation version, and the interior insulation version - and combine the both.
The Best wall has the exterior insulation layer in the rainscreen cavity, and the interior insulation layer in the wiring chase. We've just added R14 to our R23 2x6 wall or our R28 2x8 wall, and two insulated thermal breaks for the studs.
Its really just an effort to bring together all of the simple moves from the other walls, combine them, and extract the most energy performance from these easy to build options.
• Mineral wool batts, easy to handle & install, superior performance.
• Non foam exterior insulation layer that breathes.
• Insulated wire chase that preserves the integrity of the vapor and air barrier.
• Insulated wire chase that creates a thermal break.
But we can only get so far with these wall profiles. Half the battle is the thermal breaks we've introduced in these walls, but conventional platform framing introduces another host of thermal bridges at the redundant sill and top plates. As we reviewed before, even in the so called "Advanced" framing configuration these plate bridges are hardly improved.
The next step is what I've come to call Swedish Platform Framing. Like the USA New Wall this is a wall framing approach interpreted from the wall construction of Swedish off-site techniques. I see it as the next evolutionary step in stud wall framing. First there was Balloon Framing which industrialized the components of home building and revolutionized home building in the US. Then Western Platform Framing emerged, and quickly overcame the balloon frame with its superior characteristics. Now its time for the Swedish Platform Frame which will advance energy efficiency into commodity home building.
When combined with the USA New Wall profiles the Swedish Platform Frame offers a marked improvement over our conventional western platform framed walls. Less thermal bridging, simple and familiar framing techniques, and of most importance it is a wall that lends itself to off-site construction instead of fighting against you.
Come back for the Swedish Platform Frame in our next installment.