EHH week 09: advanced framing

Houses are usually built from wood, a lot of wood.  For this project, we decided to employ the Advanced Framing method to reduce the amount of wood we used.  The idea is to use just enough lumber for a strong structure, but no more.  This way we save on lumber cost, cut down fewer trees, and as a bonus get more insulation in our walls and ceilings.

The basic strategy is to install studs and joists at 24” spacing instead of the usual 16” spacing.  Additionally, extra studs called trimmers and cripples are eliminated where they can be.  Finally, we make sure that all cavities between the framing can be accessed from inside by the insulators so we don’t end up with any cold spots.  Sometimes in Advanced Framing the double plate at the top of the walls is just a single plate, but on this house aiming for extra seismic strength, we went with a double top plate.

The key to advanced framing is to stack roof joists over walls studs over floor trusses, all at 24” spacing.  That way the weight of the building gets transferred efficiently straight down to the foundation.  Windows and doors will interrupt this vertical path, and then headers are installed.  But the headers are sized individually depending on the specific load on each, rather than just using one standard oversized header at every opening.