Upcoming changes to the energy code will mean traditional construction methods will have to change. A requirement for greater efficiency for walls will mean the traditional 2 x 6 stud 16” on center wall with the cavity filled with R-21 insulation will no longer comply. There is an alternative, however, that can meet the requirements with some minor adjustments, and it can even save some money.
The code change will require walls to be about 3-1/2% more efficient than currently required. The simplest way to achieve that efficiency will be to use what is called intermediate framing. Intermediate framing uses normal 2 x 6 studs 16” on center but requires the building corners and junctions between interior and exterior walls to be designed so that insulation will extend fully into the corners and behind the partition connections.
Another significant feature of intermediate framing is treatment of headers. Headers are omitted in non-load bearing walls. Voids between header members are filled with rigid foam insulation rated at R-4 per inch. This can significantly reduce heat loss through the headers.
There is another code change coming which will allow single-member headers. A single-member header will create even more space for insulation. It can also reduce the cost for header materials and the time it takes to assemble them. In most cases a single 2 x 12 will safely span a 5-foot window opening when it carries a roof and ceiling load on a 36-foot-wide house. It can work for a 4-foot opening if a center bearing floor is added to the loading.
The code currently requires the header void to be filled with rigid foam insulation, but we are working with Building Codes Division (BCD) to allow a single member header to be filled with the same insulation material used on the rest of the wall. If this is approved it can cut the cost per header in half as well as improve the efficiency. Those using blown insulation would simply install the single member header and let the insulators net and fill the cavity. It appears this could cut the cost per header by half. We will keep you informed of the BCD action on this issue and update you in the future on other energy code changes.