September 2011: Walls Inside and Out
Walls Inside and Out
When we are talking wall retrofits, they can either be fairly high on the list or low. If the house is an older two story (balloon construction), experiencing series leakage or large infiltration losses, it will fall high on the list. The gains will be more dramatic on the conduction loss side and overall reduced CFM numbers for the entire building. Obviously walls play an integral part when simply establishing or reconfiguring the Pressure Thermal boundary at the very onset. Generally speaking if the exterior wall is experiencing a delta T of ten degrees or greater it should be insulated.
Here are some of the considerations that might come into play. If the cavities are minimal in depth or fully insulating them is to costly then sealing the tops and bottoms thereby slowing the convective loops/pathways can be cost effective. Some walls that appear to be inside may be actually outside as is the case with stairway bypasses. Some may be open along their entire length or feed into bath and kitchen soffits. Others may contain extensive wood framing and are experiencing thermal bridging as in the case of knee wall walls where studs can be turned sideways. Then there are walls by their simple construction material serve as huge thermal breaks or act negatively upon the load of the structure because they are outside of the building envelope. By insulating these walls as in the case with brick, block or concrete on the exterior side with foam or an insulation system they can be incorporated into the conditioned space and provide a significant tempering effect upon the whole building. Some of these instances can be exposed foundation walls, crawlspaces walls, fireplaces and cantilevered partitions.