Finally got the attic up to R60 and fixed those snow melt spots

I went through that same dusty process last November using the Owens Corning AttiCat machine. My attic was a mix of old rockwool and some thin R-11 batts that weren't doing anything. I spent about three days just on the air sealing because I found so many bypassed electrical boxes and a massive gap around the plumbing stack. Using the Great Stuff foam cans with the long pro-gun made it easier to reach those tight spots near the eaves.

I ended up choosing stabilized cellulose instead of fiberglass for my blow-in. I liked that it has a higher density to stop the air movement from the soffits, even though I put in those Durovent baffles like you did. I stopped at about 16 inches of depth to hit R-50, but seeing you go all the way to R-60 makes me wish I had grabbed a few more bags while I had the blower rented.

One thing that surprised me was how much quieter the house got. Beyond just the heating bill savings, the street noise from the highway nearby almost disappeared. It’s a brutal weekend of work, but not seeing those ice dams forming on the gutters once the first big snow hits is the best feeling.

I ended up taking a slightly diffrent route and went with GreenFiber cellulose instead of the blown fiberglass. My local big box store gave me the blower rental for free since I bought forty bags, and I found the cellulose much easier to work with becuase it doesn't leave you feeling like you've been rolling in needles. I managed to hit about R-50, wich is plenty for our climate in Zone 4, and the sound dampening properties were an unexpected bonus—the house is noticeably quieter when it rains now.

Instead of the thin poly baffles, I used 2-inch XPS rigid foam board cut to size between the rafters. I sealed the edges with a bead of canned foam to make sure the wind from the soffits doesn't "wind-wash" the edges of the insulation pile. It was more tedious than stapling up plastic, but it felt more secure against the draft. I also opted to skip the storage platform entirely. I’ve seen too many issues with thermal bridging trough the joists when people build decks, so I just kept the fill level consistent across the whole attic floor and sacrificed the extra storage space for better thermal performance.

I had a hell of a time with the baffles until I started using a heavy-duty staple gun with 1/2-inch staples. The little ones kept popping out of the old rafter wood. Also, I marked the joists with some tall yardsticks every few feet before blowing. It let me gauge the depth perfectly without having to stop and measure with a tape while I was blinded by the dust. It made getting to that R-60 height alot more consistent across the whole floor.

I'm still trying to wrap my head around the air sealing part. I honestly thougth just piling up more insulation was the main goal, but you guys make it sound like the gaps are the real problem. When you talk about sealing the top plates and light fixtures, do you have to vacuum out all the old dust and stuff first to get the foam to stick? I don't know much about construction, so I'm worried I'd miss half the holes if they're hidden under the wood.

Man, don't forget to double-check that hatch seal. I used some thick weatherstripping and heavy-duty latches to pull mine down tight against the frame. If there's even a tiny gap, you'll see a dark spot in the new insulation from the air leak in a couple years. Hope you wore a full Tyvek suit and a real respirator too. Blown fiberglass isn't as bad as the old batts, but it still makes me itch just thinking about it. That R60's gonna feel amazing when the first polar vortex hits though.

Quick update - the yardsticks for gauging depth were a game changer, so thanks for that tip. To the person asking about the dust: I just brushed it away from the plates instead of vacuuming. The house is much warmer now, but I'm still dealing with a small draft at the hatch. Has anyone had success using weatherstripping to seal that door tighter?