Dense-pack cellulose is decent for air sealing, but I’d be careful about expecting it to totally fix cold spots in an attic truss setup. I tried it in my last place (Cape Cod, pretty cold winters), and while it helped with drafts, I still had some uneven temps—especially around the eaves and where the truss webs made insulation coverage tricky. The cellulose settles over time too, which can open up gaps if you’re not careful with install.
Honestly, the real headache for me was making sure there was a solid air barrier before blowing anything in. If you don’t get that right, you’ll still get heat loss and condensation issues. For storage, I ended up framing a small platform above the insulation instead of going full attic truss—way cheaper and less hassle with thermal bridging. Not as much space, but it did the job for boxes and holiday stuff.
If you’re set on attic trusses for big storage or future finishing, maybe look at spray foam or a hybrid approach? More upfront cost but less fiddling with settling and air leaks down the line. Just my two cents from chasing energy bills...
Honestly, the real headache for me was making sure there was a solid air barrier before blowing anything in. If you don’t get that right, you’ll still get heat loss and condensation issues.
This part really hits home. I’ve seen a few jobs where people focused on packing in insulation but skipped over air sealing, and it always comes back to bite them—cold spots, ice dams, even some mold if things get damp enough. Insulation’s only as good as the details around it.
On the attic truss vs. rafter question, I keep going back and forth myself. Trusses definitely make storage or future finishing easier since you get that open span, but they do complicate insulation. Those webs are a pain for getting full coverage—especially with loose-fill or batt insulation. You can end up with all these little pockets where cold air sneaks through. Rafters are simpler in that sense, but you lose out on usable space unless you want to pay for stick framing and beefier lumber.
I get why spray foam is tempting for this setup—it sticks to everything, no settling, and it’s a killer air seal. The price tag is hard to swallow though, especially if you’re just looking for basic storage and not planning to finish the space anytime soon. I’ve seen some folks do a hybrid: rigid foam board over the truss chords (taped seams), then blow cellulose over that. Not perfect, but way better than just dense-pack alone.
One thing I’d add—if you’re using the attic for storage, watch your vapor barrier details too. Boxes stacked up can change airflow and trap moisture in weird spots if things aren’t sealed well.
For what it’s worth, my own place has rafters and I built a small catwalk for storage above the blown-in fiberglass. It’s not pretty but it keeps the insulation undisturbed and avoids compressing it under boxes. No regrets so far... just wish I’d spent more time on air sealing before blowing it all in.
Guess there’s no perfect answer—depends how much space you need and how much hassle you want down the road.
That’s a good point about the hybrid approach—rigid foam plus cellulose does seem to hit a sweet spot between cost and performance. I’ve run into the same headache with truss webs making it tough to get a continuous layer, especially around all those little corners. Ever tried using spray foam just in the tricky spots and then filling the rest with batts or blown-in? I’ve seen that work pretty well, but I wonder if it’s worth the hassle compared to just sticking with rafters and giving up a bit of storage. Curious if anyone’s had luck air-sealing trusses without going full spray foam...
Curious if anyone’s had luck air-sealing trusses without going full spray foam...
Yeah, that’s a tough one. I’ve seen a few projects where they tried to get cute with just hitting the truss webs and corners with spray foam, then filling the rest with batts or blown-in. It does help with air sealing in those awkward spots, but honestly, it’s a pain to do well. You end up chasing leaks around every little gusset plate and web intersection. Even with meticulous work, there’s always a spot or two that gets missed, and you can feel the drafts later.
Rafters are way simpler for air sealing—just one plane to deal with, and you can run rigid foam or dense-pack cellulose right across. But yeah, you lose out on attic storage if you go that route, which is a dealbreaker for some folks.
I’ve also seen people try to use caulk or tape on the truss joints before insulating, but that’s usually not enough in colder climates where stack effect pulls air through any tiny gap. If you’re in a milder zone, maybe you can get away with it, but up north it’s asking for trouble.
One thing that worked decently for me on a storm rebuild was using rigid foam cut to fit between the webs, sealed in place with canned spray foam. It was tedious—lots of measuring and trimming—but it got the job done without going full spray everywhere (which adds up fast cost-wise). Still not as foolproof as a continuous layer over rafters though.
If you’re dealing with high winds or driving rain (like we get here), I’d lean toward whatever gives you the best shot at a tight envelope. Air leaks are brutal after a storm—they find every path in and make drying out way harder.
Bottom line: hybrid methods can work if you’re patient and detail-oriented, but there’s always a tradeoff between labor and performance. Sometimes “good enough” is all you can get with trusses unless you want to break the bank on closed-cell foam.
- Totally get where you’re coming from. Trusses are a headache for air sealing—there’s just so many little nooks and crannies.
-
Couldn’t agree more. I tried the “spot spray foam plus batts” method in my last attic and, honestly, it was a lot of crawling around for not much payoff. Still had cold spots in February.“You end up chasing leaks around every little gusset plate and web intersection.”
- Rafters are definitely easier for that continuous layer, but yeah, losing attic storage is a tough pill to swallow. I use my attic for all the random stuff I can’t part with yet.
- The rigid foam between webs trick is clever—tedious, but clever. I’ve seen a neighbor do it and it seemed to help, but he said it took him three weekends and a lot of patience.
- If you’re in a spot where air leaks mean real moisture headaches, I’d say your attention to detail will pay off. Even if it’s not perfect, every little bit helps in the long run.
- Don’t get discouraged if it feels like you’re not getting it 100% tight. Sometimes “good enough” really is good enough—especially if you’re not ready to shell out for full spray foam everywhere.