What I learned the hard way about swapping out old windows

I hear you on the mess - when I did my first window swap (1968 ranch, so similar era), I thought I was being careful but still ended up with splinters and a dust cloud that took days to settle. One thing I’d do differently is score the paint and caulk with a utility knife all the way around before even touching the pry bar. That helped a bit on my second window, less tearing of the drywall and trim.

About the foam, I made the same mistake... stuff just kept expanding and I had to chisel it off after it dried. Someone told me to use the “window & door” specific foam because it doesn’t expand as aggressively, but honestly, even that can get messy if you’re not super light-handed. Now I just use a little at a time, let it set, then add more if needed. Still not perfect, but at least I’m not scraping blobs off my walls anymore.

Lead paint is no joke either. I got paranoid and ended up buying a test kit - turns out only one window was positive, but better safe than sorry. Old houses really keep you on your toes.

Scoring the paint and caulk is a total game changer - I skipped that on my first window too, and regretted it once I saw how much drywall paper tore off. Now I always run a sharp blade around every seam, even if it feels tedious. With the foam, I’ve started using painter’s tape along the edges so any squeeze-out peels right off, but I still end up trimming a bit here and there. Lead paint freaks me out too... those test kits are worth every penny for peace of mind, especially with kids in the house. Old windows are never as simple as they look.

With the foam, I’ve started using painter’s tape along the edges so any squeeze-out peels right off, but I still end up trimming a bit here and there.

I’m with you on the lead paint paranoia - those swabs are a must in these old houses. Curious, have you found a foam that actually expands the right amount? I keep getting ones that overfill and push the jamb out of square, even with “window & door” types.

Painter’s tape is a solid idea for foam cleanup - wish I’d thought of that before my first attempt. I’ve tried a few “low expansion” foams, but honestly, even those seem to have a mind of their own. The DAP and Great Stuff Window & Door versions both still puffed out more than I expected, especially if the weather’s warm.

Here’s what’s worked for me:
- Shake the can less than you think you need to - seems to cut down on the pressure.
- Only fill the gap about halfway, then walk away. It really does expand more than you’d guess.
- Keep a utility knife handy for trimming once it cures, but go slow or you’ll gouge the frame.

And yeah, those lead paint swabs are a lifesaver. I used them in my 1968 place and found hot spots around the sills. Ended up wetting everything down and scraping super carefully - tedious but better than risking dust.

If anyone’s got a foam brand that *actually* stays put, I’m all ears.

Only fill the gap about halfway, then walk away. It really does expand more than you’d guess.

I learned that one the hard way too. The first time I used Great Stuff, I filled the whole gap and ended up with foam bulging out like some kind of expanding marshmallow. Took ages to trim it back, and I nicked the paint a couple times. Now I just do a quick pass and come back later to see how much it’s grown.

I haven’t found a brand that stays put perfectly either. Even the “minimal expansion” ones seem to have a mind of their own, especially if it’s humid. I tried Loctite’s version last fall, and it was a little more predictable, but still not perfect. Maybe it’s just the nature of the beast?

Curious - has anyone tried those foam gun applicators? I’ve only used the straw cans, but I keep hearing the guns give you more control. Worth the extra cost?

- Definitely been there with the foam overflow. It's wild how much it can expand, even when you think you're being careful.
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I tried Loctite’s version last fall, and it was a little more predictable, but still not perfect. Maybe it’s just the nature of the beast?

Yeah, foam’s a wild card - no matter how many times I’ve used it, there’s always a surprise. I agree, the gun applicators are a game changer once you get the hang of ‘em, but cleaning the thing is no joke if you forget even once. I’ve had to toss a couple over the years... not proud of that. For small jobs, I’ll still grab a straw can sometimes just to avoid dragging all the gear out. Trimming’s just part of the process - never seen a perfectly clean install without it.

Yeah, cleaning the foam gun is a pain if you forget - even just once and it’s toast. I’ve tried soaking the tip in acetone but that only works if you catch it right away. Still grab the straw cans for quick fixes, but man, they’re messy. Never found a way around trimming either... always a bit of a hack job.

Yeah, those straw cans are basically a one-time mess. I trashed a foam gun by forgetting to clean it - just sat there and turned into a brick. Acetone trick only worked for me once, after that it was game over. Trimming is always ugly too, no matter how careful I am. Anyone ever get clean lines with that stuff? I just end up sanding and patching like crazy.

Yeah, trimming that foam is always a pain. I’ve tried a few different blades and still end up with jagged edges or big gaps. The only time I got it halfway decent was when I let it cure overnight and used a super sharp utility knife, but even then… not perfect. I just slap on more caulk and hope the trim hides my sins.

That foam is a menace, I swear. First time I did a window swap, I figured “how hard can this be?” - famous last words. I ended up with blobs sticking out everywhere and a utility knife that looked like it’d gone through a war. Letting it cure definitely helps, but I still wind up hacking away at it and making a mess. My neighbor suggested one of those little Japanese pull saws, and it actually worked better than anything else I tried, but it’s still not perfect. I’ve pretty much accepted that the trim is my last line of defense against ugly gaps. There’s a reason old houses have such thick trim, right? Sometimes I wonder if anyone ever gets that stuff looking clean without a pro’s touch… or maybe we’re all just hiding our sins under layers of caulk and paint.

That expanding foam is wild, right? I did my first window replacement in our 70s ranch and figured I’d just squirt a bit in and trim it up - easy. Ended up with a lumpy mess, and honestly, I think more foam wound up on my hands than in the gap. I let it cure overnight, but when I tried to cut it, it was like wrestling a marshmallow glued to the wall. I’ve tried everything from serrated kitchen knives to a cheap drywall saw. The Japanese pull saw is a solid tip, though - I’ll have to give that a try next time.

I totally agree about thick trim being a lifesaver. I used the biggest casing I could find at Home Depot just to hide the carnage. And yeah, caulk and paint are my best friends now. I’m convinced nobody gets it perfect on their first go unless they’ve done a dozen of these already. At this point, I just tell myself as long as it’s sealed and looks decent from five feet away, I’m calling it a win.

Expanding foam is one of those things that seems like it should be idiot-proof, right? I thought I was just gonna fill a little gap, wipe my hands, and move on. Instead, I looked like I’d lost a fight with a can of shaving cream. That stuff sticks to everything except where you want it - my dog still has a little spot on his tail from when he wandered through my “work zone.”

I hear you on the trim. I swear, whoever invented wide window casing must’ve been a DIYer with shaky hands. My first window job, I went for the dainty little molding because I thought it’d look “classy.” Joke was on me - every uneven cut and blob of foam was right out in the open. Now it’s chunky trim or nothing. Caulk is basically my eraser at this point.

The Japanese pull saw is magic, but you gotta respect it. First time I used one, I got a little too confident and took a chunk out of the drywall. Live and learn... At least foam is forgiving once you cover it up.

Honestly, I’m convinced window replacement is like cutting your own hair - looks easy till you’re halfway through and realize you have no idea what you’re doing. If you can get it sealed up and not drafty, call it good. Nobody’s crawling around with a magnifying glass checking your work anyway... unless your in-laws are extra nosy.

Anyway, glad I’m not the only one who’s had expanding foam adventures. Next project: figuring out how to get dried foam off your hands without losing half your skin.

- I get the appeal of wide trim, but honestly, I’ve had better luck with the narrow stuff - just takes a bit more patience and a sharp utility knife for cleanup.
- For foam, I switched to the low-expansion type. Less mess and easier to control, especially on older, uneven frames.
- Not sure if everyone skips the backer rod, but it’s saved me from overdoing the caulk and foam a few times.
- Agree, nobody inspects your work up close... but I still notice my own mistakes every time I walk by that window.

Narrow trim does look cleaner, but I swear it tests my patience every time. My old house has frames that are anything but square - lining up the narrow stuff took a few choice words and a lot of caulk. I’m with you on low-expansion foam though. The regular kind once pushed my jambs out of alignment… not my finest hour. Backer rod’s one of those things I didn’t use at first, but now I keep a roll handy. Makes the caulk go further and keeps things tidy. Still, every time the sun hits that one corner just right, I see my less-than-perfect miter.

That’s the thing with older homes - nothing’s ever square, and narrow trim really does magnify every imperfection. I’ve learned to dry-fit everything twice, but even then, a little creative caulking is inevitable. Backer rod was a game changer for me too. Those miters always seem perfect until the light hits just right... but honestly, most folks will never notice.

You nailed it - old houses just don’t play by the rules. I always expect to spend more time shimming and scribing than actually setting the window. Even with laser levels, you end up splitting the difference between plumb and what looks right from the street. I’ve found that using wider trim can help hide some of those wavy plaster lines, but sometimes you just have to embrace a little “character.” And yeah, backer rod plus flexible caulk is my go-to for those gaps that seem to grow overnight. Funny how you notice every tiny flaw during install, but a week later it all blends in.

Wider trim definitely helps, but I’ve had spots where even that wasn’t enough - ended up feathering out joint compound to fake a straight line. Ever tried using corner bead or anything else to deal with those extra wonky walls?

Ever tried using corner bead or anything else to deal with those extra wonky walls?

Yeah, I’ve wrestled with some pretty uneven plaster in my 1950s place. Wider trim helps hide the worst of it, but sometimes you hit a spot where nothing sits flush - no matter how much you wish it would. I’ve actually used metal corner bead once, but honestly, it felt like overkill for a window opening unless the wall was *really* out of whack. I usually end up doing what you did: feathering joint compound and hoping nobody looks too closely.

One trick that worked for me on a particularly bad window was scribing the trim to fit the wall. It’s a pain - lots of back and forth with a pencil and block plane - but it beats having a massive gap or a mountain of mud to sand down later. Still, there’s always that one spot where the caulk gun is your best friend...

Old houses keep you humble, that’s for sure.