Dense-pack cellulose in old walls is kind of a mixed bag, honestly. I did it in a 1920s bungalow a few years back, and while it helped some, it wasn’t the magic bullet I hoped for. The main problem was exactly what you’re talking about: all the weird blocking, wires, and random framing inside those old walls. You can drill and blow cellulose all you want, but unless you’ve scoped every cavity, you’ll probably miss spots or hit dead ends. In my case, I found out later with a thermal camera that some sections barely got any insulation at all because of fire stops and cross-bracing.
The knob-and-tube issue is real too. Technically, you’re not supposed to dense-pack around active knob-and-tube since it needs air space to cool. Some folks just do it anyway, but I wasn’t comfortable with that risk. Ended up skipping a couple rooms until I could rewire.
Honestly, I got way more bang for my buck sealing up the attic floor and rim joists in the basement. That’s where most of the air was leaking in or out anyway. It’s less glamorous than “insulating the whole house,” but the comfort difference was immediate—no more freezing feet in winter or roasting upstairs in summer.
If you’ve got easy access to the attic, that’s usually the best place to start. Dense-pack is fine if you’ve already dealt with wiring and know what’s inside your walls, but otherwise, it can turn into an expensive guessing game. If you’re on a budget or just want to see a quick improvement, focus on the low-hanging fruit first... then worry about the walls if you still feel drafts.
Just my two cents from sweating through it myself.
Yeah, I hear you on the attic and rim joists—those spots are often the real troublemakers. I once spent a weekend crawling around my own attic with a caulk gun and some leftover batts, and honestly, the difference was night and day. Walls get all the attention, but unless you’re gutting things or already rewiring, it’s just not worth the headache right out of the gate. Plus, I’ve seen folks spend weeks chasing down every weird nook in old walls, only to find out they still had cold floors because of leaky sills. Sometimes the boring stuff pays off fastest.
“Sometimes the boring stuff pays off fastest.”
Couldn’t agree more, but I’ll throw in a twist—sometimes the “boring” stuff is where you get to be creative, too. Here’s how I usually break it down:
- Attic and rim joists: Weekend project if you’re motivated. You’ll sweat, but it’s doable.
- Crawlspaces or basements: Another day or two, depending on how much you like spiders.
- Walls: Unless you’re already opening them up, I’d leave ‘em for last. Dense-pack cellulose is cool, but it’s a pain if you’re not already remodeling.
- Sills and weird corners: These are the sneaky culprits. I once found a draft coming from a spot behind a built-in bookshelf—took me hours to track it down.
Honestly, I’ve flipped houses where just sealing up the attic and basement made the place feel totally different. If you’re looking for bang for your buck (and time), start at the top and bottom. The rest can wait unless you’re going for perfection. Sometimes “good enough” is actually pretty great.
That’s a great breakdown. I’ve noticed with older homes like mine, the “weird corners” are almost the rule, not the exception. Last winter, I ended up crawling around my dining room floor with a candle just to spot where the cold air was sneaking in—it was coming through a gap behind some original trim work. Sealing that made a bigger difference than I expected.
I agree about starting at the top and bottom. In my case, insulating the attic was one of those jobs that seemed dull, but it made the entire house quieter and more comfortable. The walls, though... I’m always nervous about messing with them because of the old plaster and lath. Sometimes I wonder if there’s a way to add insulation without tearing up all that character. Has anyone tried any less invasive methods for wall insulation in an older place? I’m half tempted to just leave them alone and focus on tightening up everything else.
Blown-in cellulose is probably your best bet if you want to keep the old plaster and lath intact. It’s not totally non-invasive—you’ll have to drill small holes between the studs—but it beats gutting the walls. I’ve done it in a couple of 1920s places, and as long as you patch carefully, you’d never know. That said, sometimes those old walls are so uneven that air still sneaks around, so I always say: focus on air sealing first, then worry about what’s inside the walls. The character’s worth preserving, but not at the cost of freezing every winter...