Getting Interior Air-Barrier Details Right
Installation of the Intello Plus membrane on the inside of the third floor of the 2020 FHB House happens in conjunction with additional wall framing to get a good air-seal and to make room for lots of cellulose insulation.
The third floor framing on the 2020 Fine Homebuilding house has been completed, so it’s time to move on to the air barrier—which on this house is on the inside surface of the walls and roof. BPC Green Builders has transformed this former attic, reframing with scissor trusses to make one big open space that will become a large family room.
The trusses make installing cellulose insulation much easier, plus they create a nice consistent plane to install the Pro Clima Intello Plus smart air- and vapor-control layer. The build team chose Intello Plus because it has reinforcing fibers built in to resist the force of the dense-packed cellulose and hold it tightly into the wall and roof cavities before drywall gets installed.
The carpenters, lead by builder Albert Jensen-Moulton, start by stapling the Intello Plus down to the subfloor and taping it to the exterior wall plate so that the air barrier will wrap under the kneewall that comes next.
They install the knee-wall bottom plate over the membrane on the floor, use their trusty STABILA spirit level to align the beveled top plate, and then infill with studs.
Next the team staples more sheets of Intello Plus on the ceiling, leaving it just high enough to allow them to wrap the sheet on the floor up the wall and tape it to this ceiling air barrier.
Now that the kneewall is built and all pieces of the interior air barrier are in place and about to be closed up, the project is almost ready for the dense-pack cellulose insulation.