Tackling Old Windows: My Weekend Project Went Better Than Expected

I totally get what you mean about wood shims “biting” better. I’ve tried mixing materials too, especially when I’m running low or trying to make things work with what’s in the garage. One thing that’s worked for me, especially with older windows that never seem to be square anymore, is stacking a thin bead of caulk behind the final shim (wood or composite). It kind of locks everything in place and keeps those sneaky plastic shims from sliding out over time.

If you’re aiming for better insulation, I’ve also found that wood shims tend to seal up gaps tighter, which helps cut down on drafts. Plastic ones sometimes leave a hairline space unless you’re really careful. Little stuff like that adds up with old windows - my utility bill dropped a bit after I redid ours last winter.

It’s not always pretty, but sometimes it’s just about making do with what you’ve got and adding a little tweak here and there.

- Totally hear you on the “make do with what’s in the garage” approach. My last window job looked like a Frankenstein project with all the mismatched shims and random caulk tubes I found hiding behind the paint cans.

- That caulk-behind-the-shim trick is genius. I’ve had plastic shims pop out mid-winter and it’s like, “Well, there goes my heating budget for the month.” Wood shims just seem to stay put, even if they’re a little rough around the edges.

- Not gonna lie, I’ve spent way too much time fussing over tiny gaps that nobody else would ever notice. But you’re right, those little tweaks add up. My partner rolled their eyes at me for obsessing over a draft by the couch, but now they’re the first to brag about our lower energy bill.

- Sometimes it’s not about perfect, it’s about “good enough for now.” Old windows have a mind of their own anyway. If you can get them to stop rattling in the wind, you’re already winning.

Interesting to hear all these different approaches - makes me wonder, has anyone tried those self-adhesive foam tapes for gaps? I’ve had mixed luck. Sometimes they hold up through a couple of seasons, but other times they peel off or compress too much and stop doing their job. I keep going back to old-school wood shims and caulk for anything that actually matters.

Have you noticed any particular spots in your house that are always drafty no matter what you do? In my experience, it’s usually the meeting rails and the corners that give people the most grief. I’ve even seen folks try those shrink-wrap window kits in older homes - some swear by them, others say it just looks tacky. Curious if anyone here has found a long-term fix that doesn’t involve full replacement.

I get the “good enough” mentality, but sometimes I can’t help but think about what’s hiding behind the trim... rot, nests, who knows what else. Ever opened up a window you thought was fine and found a bigger mess than expected?

Ever opened up a window you thought was fine and found a bigger mess than expected?

Oh man, yes. Last spring I went to fix a squeaky sash and wound up pulling off some trim - there was a whole mess of old wasp nests tucked in there, plus some crumbly insulation that basically turned to dust. I’ve tried those foam tapes too, but like you said, they just squish down after a while. Caulk’s been my go-to for the corners, but it’s definitely not perfect. Meeting rails are the bane of my existence... I swear there’s always a tiny draft no matter what I do.

I get what you mean about caulk not being a magic fix, especially around those meeting rails. But does anyone else feel like sometimes the foam tape gets a bit of a bad rap? I used some thicker weatherstripping tape on our oldest window (the one that sticks every time it rains), and it actually held up okay through the winter. Maybe it depends on the brand or how tight the sash is?

About the crumbly insulation - did you just vacuum that out and leave it, or did you try to replace it? I keep finding these weird gaps behind my trim, but I'm never sure if stuffing more insulation in there actually helps with drafts or if it's just making a mess for next time.

Honestly, I’m still not convinced caulk is worth the mess for anything but obvious cracks. Feels like I spend more time cleaning up than sealing out cold air. Anyone else try something totally different?

I’ve always wondered if we’re all just a bit too quick to reach for caulk when it comes to old windows. I mean, yeah, it’s great for big gaps, but I’ve had more luck with rope caulk in the past - especially for seasonal fixes. It’s not permanent, but it keeps drafts out and peels right off when you need to open things up again. Less mess, for sure.

With those gaps behind trim, I used to shove fiberglass in there thinking more was better, but honestly, sometimes it just creates weird lumps or pushes the trim out. Lately, I’ve tried using low-expansion spray foam in small doses. The trick is not to overdo it or you’ll end up with a bigger mess (and possibly warped wood). Can’t say I’ve found a perfect solution, but it definitely cut down on cold spots this winter.

As for weatherstripping tape, totally agree - it gets a bad rap. Some brands are junk, but others stick around for years if you prep the surface right. Maybe it’s more about matching the thickness and material to the window than anything else.

You’re spot on about rope caulk - it’s massively underrated for old sash windows. I used to be a “caulk everything” person, but it’s a pain if you want to open the window before spring. Rope caulk is easy to remove and doesn’t leave that sticky mess behind. On the spray foam, I’ve learned the hard way that less is more... once had to pry a piece of trim off because it bowed out from too much foam. Weatherstripping tape is hit-or-miss, but like you said, surface prep makes all the difference. Sometimes I think half the battle with old windows is just picking your battles.

Sometimes I think half the battle with old windows is just picking your battles.

Ain’t that the truth. I’ve lost count of how many times I’ve stood in front of a wavy-glass sash window, wondering if it’s worth another round with the weatherstripping - or just give up and call it “historic character.” Rope caulk’s a solid call, but does anyone else find it gets brittle if you leave it in too long? I’ve pulled out stuff in the spring that crumbled like old Play-Doh.

About spray foam, I’m with you there. Folks always think more is better, but that stuff expands like it’s got a mind of its own. Ever see someone use the “big gap” kind in a 1/4" crack? Suddenly the trim’s sticking out like it’s trying to escape the wall. Learned that lesson on a 1920s bungalow - never again.

Curious, have you tried those silicone weatherstrips? I’m skeptical, but a client swears by them. I just worry they’ll peel paint or leave marks. Or maybe that’s just my luck with “miracle” fixes…

Funny you mention silicone weatherstrips - I’ve installed them a handful of times, mostly in homes where the owners wanted something less visible than felt or foam. They do seal well, but I’ve seen them pull up paint on older sashes, especially if the surface wasn’t prepped right. Sometimes they just won’t stick if there’s any dust or old finish left. I still lean toward interlocking metal for longevity, though it’s a pain to retrofit. Has anyone tried those magnetic strips? I’ve heard mixed reviews but never seen them in action on a double-hung.

- I actually had better luck with silicone on my 1930s windows than with metal interlocks. The metal ones were super draft-proof but made the sashes stickier, and I hated the scraping noise.
- Silicone strips did peel a bit of paint, but only where I rushed the prep. Sanding and a quick wipe-down made a big difference.
- Magnetic strips - tried them once on a rental. They sealed well but looked clunky on double-hungs and didn’t last through a winter of opening/closing.
- For me, silicone’s the sweet spot between stealthy and easy to replace. Metal’s great, just not for my patience level...

Funny, I had the opposite issue with silicone - mine kept slipping in the summer humidity and left a gummy mess when I tried to reposition. Maybe I just got a cheap brand?

Silicone strips did peel a bit of paint, but only where I rushed the prep. Sanding and a quick wipe-down made a big difference.

Did you notice any long-term issues with paint around the sash after a couple seasons? I keep worrying that the constant flexing will eventually crack the paint no matter how careful I am. Metal interlocks drive me nuts too, but at least they’re predictable... unless you miss a nail and end up with a bent piece.

I’ve actually had better luck with the foam weatherstripping, even though everyone seems to swear by silicone. The foam’s not as invisible, but it’s way easier to replace if it gets messed up or peels paint. I get what you mean about worrying over the paint flexing - I had a spot where the sash kept sticking after a few months, and sure enough, the paint started cracking right along the edge. I prepped pretty carefully too, but maybe old paint just doesn’t like being flexed that much.

Metal interlocks are a pain for me too, especially since my windows aren’t exactly square anymore. I bent two pieces before I gave up and just lived with a little draft. Have you tried the felt strips? They’re not perfect for big gaps, but they don’t seem to mess with the paint as much in my place. Just curious if anyone else has found something that holds up without making a mess or needing a ton of prep every year.

I’ve actually used the felt strips on a couple of our old casement windows, and they’ve held up better than I expected, though they do get kind of grimy after a couple years. The foam ones were easier to put in, but I had that same issue with paint peeling when I tried to pull them off. Silicone looked great at first but it started coming away in places where the window frame wasn’t totally flat - old house problems, I guess. Have you ever tried those V-shaped vinyl strips? I was tempted, but not sure if they’d just pop out with all the shifting in winter.

Have you ever tried those V-shaped vinyl strips? I was tempted, but not sure if they’d just pop out with all the shifting in winter.

I’ve actually messed around with those V-shaped vinyl weatherstrips on my 1930s double-hungs, and honestly, they’re a bit of a mixed bag. On the plus side, they give a pretty tight seal right off the bat - way better than the old felt stuff in terms of blocking drafts. But yeah, you’re right to be suspicious about them staying put. If your frames swell and shrink a lot (which mine do every time the humidity changes), you might find corners popping out or the strip sliding a little. It’s not a total dealbreaker, but it does mean you’ll probably be nudging them back into place every now and then.

One trick I found helpful: I ran a tiny bead of clear caulk underneath the strip before pressing it in. Not enough to glue it down forever, just enough to give it some grip. It made a big difference last winter - less shifting, and I didn’t have to keep fiddling with them every other week.

But I’ll be honest, nothing’s perfect for old windows. The foam ones are definitely easier to install, but like you said, they can be a nightmare to remove if you ever need to repaint or do repairs. I had paint peel off in sheets once - learned that lesson the hard way.

If you’re already dealing with uneven frames, I’d say give the vinyl a shot on one window first and see how it holds up through a season. They’re not super expensive, so it’s not a huge loss if they don’t work out. At least you won’t have to scrape off sticky residue like with foam.

Funny thing is, after all these experiments, I sometimes think good old-fashioned rope caulk is the most forgiving for weird gaps - ugly as sin, but it comes off clean in spring.

Old houses definitely keep us on our toes...

I’m with you on rope caulk being ugly but practical - I used it for a couple seasons and yeah, it’s not winning any beauty contests, but it does the job. I actually tried the metal spring bronze strips once too, thinking they’d be more “authentic” for my 1920s sashes. Honestly, installing those was a pain - lots of tiny nails, and my frames weren’t exactly straight to begin with. Ever mess with those, or are they just more trouble than they’re worth for most folks?

Yeah, I’ve tangled with the spring bronze strips before - thought they’d be a slam dunk for my 1915 windows. The reality was, let’s just say, a lot more fiddly than I hoped. My frames were a little warped too, so getting the strips to actually stay flush was an exercise in patience. I kept second-guessing if I was even doing it right. They do look pretty sharp once in, but honestly, for the time and hassle, sometimes I wonder if just sticking with the “ugly” options like rope caulk is the smarter move, at least for drafty spots you don’t see much. Anyone actually get those bronze strips in without a headache?

I get where you’re coming from, but honestly, I’d take the bronze strips over rope caulk any day. I’ve tried both, and while the strips are definitely a pain to get right - especially with old, uneven frames - once they’re in, they’re good for years. Rope caulk just never lasted for me. It always looked rough and needed redoing every season. The initial hassle with bronze is annoying, but I think it pays off in the long run. Maybe I’m just stubborn, but I’d rather wrestle with it once than mess with drafts every winter.

That’s been my experience, too - bronze strips are a pain at first, but I barely think about them once they’re in. Curious, though: have you ever had issues with condensation after sealing up tight? I noticed one of my old sashes started sweating a bit more after I did all the windows. Not sure if that’s just my drafty house or something with the strips themselves.

Funny you mention condensation - I've actually had the opposite happen in my 1920s place. After I put in the bronze strips, the drafts dropped off, but so did the window sweating. I wonder if it has more to do with how humid your house is overall? Sometimes sealing up too tight can trap moisture inside, especially if ventilation isn’t great. Did you notice any difference in other rooms, or just that one sash?

- Really interesting point about the humidity.
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Sometimes sealing up too tight can trap moisture inside, especially if ventilation isn’t great.