Energy Efficient Framing

GreenBuildingAdvisor.com

Our contractor might disagree with the use of the phrase "Energy Efficient Framing" since it was his crew that put all the energy into framing the house, but with a little extra energy put into planning the framing it's possible to save a lot of lumber and get some extra insulation in the walls ultimately leading to a more efficient building envelope. Mom and Dad really wanted a super-insulated home so we came up with a system that would allow for a lot of insulation in the roof and walls, as well as introducing thermal breaks between the interior and exterior sides of the walls whenever possible.

Key components of Energy Efficient Framing are:

Stacked Framing - Aligning all the framing members vertically, from roof to wall to floor will allow for direct transfer of loads down to the foundation. This can eliminate the need for double top plates on walls and other members used to transfer loads horizontally.


Double-Stud Wall 24" O.C.- Using 2x6's at 24" on center instead of 2x4's at 16" on center is often recommended because even though it uses slightly more lumber it allows for two extra inches of insulation in the wall. We wanted even more insulation so we decided to go with a double-wall system comprised of two parallel walls framed with 2x4's at 24" on center and spaced 1" apart. This allowed for a total of 8" of insulation in the wall cavity and also created a thermal break between the inside and outside surfaces of the wall.

2-Stud Corners - Conventionally frames walls usually will use at least three studs in the exterior corners of the wall to support sheathing on the outside and drywall on the inside. All this wood means there isn't much room for insulation. Energy Efficient Framing typically uses two studs to support the sheathing and metal clips to support drywall allowing for more insulation in the corner. With the double-wall system we used we end up using four studs in the corners, but still have plenty of room to get a lot of insulation in there.

Eliminate Unnecessary Headers - Headers are only needed to transfer loads over openings in load bearing walls, but often they get put in over any opening regardless of whether or not they are actually needed. The north and south walls of this house are the load-bearing ones, so those are the only walls we put headers into.

Engineered Lumber for Long Spans -For floor and roof framing longer spans require deeper members and to get these out of solid lumber is not only expensive but it's a lot of tree. While we used conventional lumber for all the wall framing we used engineered wood joists for the floor and roof framing. The second floor and roof is made up of two 14' long spans, but we able to use 32' joists for the roof framing so a single member made both spans and formed the roof overhang.

Design Module - The overall foot print and form of the house is based on a 2' module to work with conventional sheet material sizes, thus minimizing material waste. The main level footprint is 28'x40' and the second floor level is 28'x24'.

THIS LINK provides additional information on Energy Efficient or Advanced Framing Techniques.

South elevation taking shape

View across the kitchen

View across the bedroom

The main purpose of Energy Efficient Framing is to improve the efficiency of the home, not the process of building it. While we did make an effort to eliminate unnecessary framing elements and minimize material waste the bigger goal is to maximize insulation in the roof and walls.