Where do you even begin with swapping out old windows?

I swear, old houses are like time capsules for weird stuff.

No kidding—just last month I pulled a window from a 1920s bungalow and out dropped a handful of marbles and what looked like an ancient cigarette tin. Never dull. The “held together with rusty nails and optimism” bit is pretty spot-on; I’ve seen frames where the only thing keeping them up was a thick coat of paint.

When you start swapping out windows in these older places, the surprises are almost guaranteed. I always tell folks to expect at least one curveball—hidden nests, mystery wiring, or framing that’s not even close to today’s standards. The trick is to go slow and check everything as you peel it back. If you rush, you miss rot or pest damage, and then you’re doubling your work later.

One tip: measure everything twice, then measure again. Old houses rarely have square openings anymore. And don’t get me started on the insulation—sometimes it’s newspaper, sometimes it’s...well, whatever critters have dragged in.

Still, there’s something satisfying about bringing those drafty frames up to snuff, even if it takes a few more hours (and stories) than planned.

Can confirm, nothing’s ever square in these old places. I’ve seen window openings off by almost an inch from top to bottom. You really do have to check for rot and weird framing before you even think about putting in the new unit. Sometimes I end up rebuilding half the sill just to get a solid fit. And yeah, insulation’s a wild card—pulled out a wad of 1960s coupons once. Take your time, and don’t assume anything’s standard.

That’s wild about the 1960s coupons—closest I’ve come was a handful of ancient insulation that looked like it belonged in a museum. I swear, every time I think I’ve measured right, the frame throws me a curveball. Is it just me, or do these old houses seem to shift over time? I ended up having to custom order one window because nothing off the shelf would fit. Part of me loves the character, but wow, it’s never straightforward.

Totally get what you mean about those old houses throwing curveballs. I’ve been through it more than once—measure three times, still manage to be off by a hair because the frame’s out of square or the walls have settled just enough to mess with things. It’s like the house is actively resisting change sometimes. And yeah, they definitely shift over time. I read somewhere that even humidity swings can nudge things just enough to make a tight fit suddenly not-so-tight.

When I did my kitchen windows last fall, I hit that same wall—literally and figuratively. The opening was almost half an inch smaller at the top than the bottom, so even though I thought I was being super careful with measurements, nothing standard would fit. Ended up going custom too, which cost more and took longer than I’d hoped. But honestly, after wrestling with shims and caulk on other projects, it was worth it for the clean install.

If you’re tackling another window soon, here’s how I try to keep myself sane: first, always measure in three spots—top, middle, bottom (and side-to-side too). Write everything down right away because it’s easy to mix up numbers. Second, check if the frame is actually square by measuring diagonally both ways. If those numbers are off by more than a quarter inch or so, you’ll probably need custom or at least be ready to do some creative trimming.

One thing I underestimated was how much old trim would splinter when I removed it. If you want to reuse any of that original woodwork (which looks awesome but is sometimes brittle as heck), go slow and use a thin pry bar. Sometimes the nails are so old they just snap.

I hear you on loving the character. There’s something about those quirks that makes the place feel alive, but man, it’s never just a pop-in-a-new-window-and-go situation. Sometimes I envy folks with newer builds...but then again, they don’t get to find weird stuff in their walls like 1960s coupons or ancient insulation. Guess it’s all part of the adventure.

Man, I swear my old place is actively plotting against any kind of energy efficiency. Every time I think I’ve sealed up every draft, some weird gap appears out of nowhere... usually right after a weather swing. You nailed it about the trim—mine basically exploded when I tried to pry it off. Still, nothing beats that feeling when you finally get a snug window in and realize your heating bill might not make you cry this winter. I’ll take the quirks over cookie-cutter any day, but yeah—it’s never boring.

I get the appeal of “quirks,” but honestly, after a few months wrestling with my 1940s windows, I’m starting to see the upside of cookie-cutter. You mentioned,

“nothing beats that feeling when you finally get a snug window in and realize your heating bill might not make you cry this winter.”

Honestly, I get where you’re coming from. Once I started pulling out my 1950s windows, it was a can of worms—out-of-square framing, rotted sills, even found some knob-and-tube wiring hiding in there. “Character” starts to feel like a euphemism for “surprise work” after a while. Still, there’s something satisfying about getting everything lined up and tight, even if it takes way longer than planned. But yeah... sometimes I envy folks with new builds and straight walls.

“Character” starts to feel like a euphemism for “surprise work” after a while.

That’s the truth. I’ve never pulled out an old window and had it go exactly as planned. You get into those sills and suddenly you’re dealing with rot, weird framing, or some ancient wiring that makes you stop and scratch your head. The out-of-square openings are a classic—sometimes you wonder if the house ever had a right angle to begin with.

Whenever I’m starting a swap on something pre-1960s, first thing I check is the condition of the framing and sill. If there’s any softness or visible water damage, you’re looking at extra work before the new window even goes in. And if you hit knob-and-tube, that’s its own can of worms—sometimes it’s best to bring in an electrician rather than risk anything.

I know new builds are tempting, but honestly, getting those old walls straightened out and tight feels pretty good when it’s done. Just gotta expect the unexpected and pad your timeline. Did you end up reframing any openings, or were you able to shim everything square? Sometimes I think shims are the unsung heroes of old house work...

Shims are lifesavers, no doubt. Last time I swapped out a 1940s double-hung, the opening was so far off I had to reframe half of it. Ended up air sealing the heck out of it, too—made a big difference on the drafts. Funny how a “simple” window job always snowballs.

That’s the thing with old houses—what looks like a quick swap almost always turns into a bigger project. I’ve run into those out-of-square openings more times than I can count. Sometimes you’re reframing half the wall before you even get to the window itself. Air sealing after install makes a world of difference, though—especially in these drafty old places. Honestly, shims and patience go hand in hand on these jobs... You do what you have to, and it always pays off when you feel that tight seal in the end.