Step 22a – Complete the Conditioned Attic

I had already installed the flooring for the conditioned attic when I assembled the ductwork of the house, but now it was time to throw up some walls and air seal it. I would also need to install some baffles so that the loose fill cellulose insulation in the attic will maintain an even distribution as it extends up over the top of the conditioned attic. The conditioned attic must be fully insulated and air sealed just like the rest of the conditioned space of the house.

First, I cut four sheets of drywall to fit the four walls of the conditioned attic and weaved them up through the trusses and into the attic. This was no easy task and if I had to do it over again I would have done it before I installed the ERV and ducts, but I made it work. I screwed the drywall into the framing, and then used canned spray foam to air seal the tiny gaps between the sheets of drywall from the outside. As you can see, the attic has a trapezoidal type shape to it.

I also air sealed the cracks between the plywood flooring of the attic from below, as well as the gaps between the flooring. Above you can see the entrance to the conditioned attic and the foam ensuring the flooring is airtight. I also air sealed penetrations for the lighting, ducts, power for the ERV and steamer, and water line and drain line for the steamer.

The final step was to install the baffles that will ensure there is a consistent amount of insulation surrounding the conditioned attic. Its difficult to take a picture of what exactly I’m talking about, but in the center of the pic above you can see a sort of open space between the conditioned attic and the white line at the top of the pic that is the edge of a sheet of drywall. This space will be filled with cellulose insulation. You can see a side view from the pic below and hopefully get an idea of how I built the baffles with a layer of drywall that creates a 16″ space all around the attic to keep the cellulose in place.