Attic Wall

September 9, 2020

Recently I made changes to how the attic would be built and finished the final wall that separates the attic from the loft.

With no ceiling in the attic space, it will be easy to hang the HVAC equipment from the steel above.

After many iterations and much consulting with Adam and Peter, I was starting to think I needed to use whatever space above the attic I could to make the ceiling taller. Eventually Adam suggested I leave it open and just insulate the walls and floor really well. Brilliant.

The equipment will be in a semi-conditioned space, but since I’m using all insulated plenums and ductwork it won’t cause any problems.

Having permanent access to the space above the structure also meant I could push back many tasks that were blocking closing up the ceiling and will have more access for maintenance in the future without having to rip up finished walls.

The wall is angled, sits between a level subfloor and a vaulted ceiling and has 2×12 let in on one end to distribute the weight, making these boards very complex to cut.

Though small, this is the most complex wall in the build. I checked measurements between the model and the building and then crafted the 2×6 studs for the angled wall.

I also ripped the 2×12 at the same angle as the wall to maximize surface area where it makes contact with the attic floor joists.

The design places the studs directly beneath the rafters but the wall and subfloor below have a different pattern entirely. To overcome this, I used a spare 12ft 2×12 to distribute the downward force along the subfloor evenly.

The load capacity of the original wall would have actually been sufficient, but I wanted a wider margin of error and 2x4s are cheap.

The wall below was originally framed with 2x4s, 24 in. OC. Now that it’s a load bearing wall, it needed to be strengthened. So I sistered in additional 2x4s to increase the wall’s vertical load capacity.

I cut the rafters back using a new reciprocating saw blade called “The Axe” which was shockingly effective at ripping through wood.

Then I framed the wall and removed the remaining rafter segments to open up the attic.

One the left side of the attic is an opening large enough to easily get 4×8 sheets of material into the attic. This will be very handy for the rigid foam board insulation I’ll soon be attaching to the top of the rafters.

Finally, I terminated the rafters with a 2×10 and sheathed the back side of the wall with OSB to add shear strength and provide a backer for the closed cell spray foam that will go into those cavities.