Thursday, March 26, 2015

Giant Holes in the Attic - Air Sealing again

Sun Tunnel in attic
Kitchen fan vent in the attic
Fiberglass around the kitchen fan vent - the black discoloration is years of dust going through the fiberglass where it functions as a filter.
Almost every day I work in the attic trying to get a basic level of insulation in place before it gets too hot to work up there - probably within the next 3 weeks.

I am installing 5.5 inches of UltraTouch denim insulation on top of seriously compressed fiberglass batts squashed down to one inch. The UltraTouch is supposed to be R-21, but that may be overestimating a little. I figure what I'm doing will get me to at least R-20 in the 5.5 inch ceiling joists. I think that just this small amount will make a tremendous difference for the summer. But for my area the code requirement is R-38. I'll get way beyond code when I install 10+ inches of cellulose later in the year.

Anyway, to ensure that the insulation can do it's job and not just function as a filter (see fiberglass photo above), you've got to do the hard work and air seal what you can get to. My Sun Tunnel is way out at the edge of joists between rafters, I cannot physically get there. I am going to put an extension tube on a can of spray foam and squirt the hell out of what I can reach.

I was able to air seal around the kitchen vent fairly easily. I used foam board and Prosoco Joint and Seam Sealer. I was a little over exuberant in using the seam sealer as usual, but it is sealed.

The weather is finally like springtime here. We might get frost this weekend, but things are blooming and it is really lovely. I hope you are enjoying some springlike weather.


  1. I love to see all of your progress! Where is the sun tunnel?

  2. The Sun Tunnel is in the basement stairway. It provides great light in the daytime so you don't need to turn on a light.