Trying to decide how to tackle the window trim in my 1960s ranch, and I keep going back and forth between mitered corners and just doing simple butt joints. I know miters look a bit fancier and “finished,” but I also hear they can open up over time, especially if your house shifts or the wood moves with the seasons (which mine definitely does—old house problems…). Butt joints seem kind of basic, almost like cheating, but I’ve seen some craftsman-style homes where they actually look intentional and pretty cool.
I’m not super experienced with trim work, so I’m worried about getting those miter cuts perfect. But at the same time, I don’t want my corners looking sloppy a year from now. Is one method really better for durability? Or is it just about looks? Also, does caulking or using wood filler actually keep miters from gapping, or is that just a temporary fix?
If you’ve done this before—especially in an older home—what worked for you? Any regrets or things you’d do differently?
I’m right there with you on the house shifting thing—my place is from the ‘50s and those walls definitely have a mind of their own. I tried miters in my dining room last year, and they looked awesome at first…but by winter, I was seeing gaps in a couple corners. I did use caulk, but it only hid things for a while before the cracks came back. Not sure if that’s just my bad luck or what.
I’ve been thinking about butt joints for my next room because, like you said, sometimes simple just works—especially with craftsman trim. But here’s what keeps bugging me: does the wood quality make a bigger difference than the joint type? Like, would using pre-primed finger-jointed pine hold up better than solid wood in an old house that moves? Or is movement just movement, no matter what?
Curious if anyone’s had better luck with one type of wood or maybe even a different trim profile that hides gaps easier…
I totally get what you mean about the shifting—my place is a '60s ranch and the walls are never quite square. I went with butt joints in my bedroom last fall, using pre-primed finger-jointed pine, and honestly, they’ve held up better than the miters in my living room. I think the finger-jointed stuff flexes a bit more, so the cracks aren’t as noticeable. Solid wood looked great at first, but I had more movement and separation over the winter. For me, the craftsman profile hides the gaps way better too. Not perfect, but less stress every season when things move around.
I hear you on the butt joints being more forgiving, especially with finger-jointed pine. But I’ve actually had better luck with miters—if I take the time to glue and pin them, then run a small bead of flexible caulk in the seam before painting. My house is late '70s, so nothing’s truly square either, but I like how miters look when they hold up. The trick for me has been using a coping saw on inside corners and pre-painting everything. Maybe it’s just my climate (lots of humidity swings), but butt joints sometimes still open up on me, especially if the trim isn’t perfectly flush with the wall. Anyone else notice that caulked miters can last longer if you prep right?
I’ve noticed the same thing with seasonal movement—my 1958 place gets wild humidity swings, and the miters on my north-facing windows still opened up even after caulking. I wonder if the insulation or air leaks behind the trim make a difference? Maybe butt joints are just less prone to telegraphing those shifts, but they do look a bit plain unless you really lean into that craftsman vibe. Anyone ever try using backer rod behind trim to help stabilize things? I keep wondering if that’s overkill.
I wonder if the insulation or air leaks behind the trim make a difference? Maybe butt joints are just less prone to telegraphing those shifts, but they do look a bit plain unless you really lean into that craftsman vibe.
Yeah, I’ve run into the same issue with miters opening up in my 1960s place. North side gets hammered by wind and moisture, and even after stuffing some insulation behind the trim and caulking, those corners still split in winter. I do think air leaks and drafty spots behind the trim play a part—every time I pull off old casing, there’s gaps and cold air coming through.
Tried butt joints on one window as a test. They’re definitely less fussy about movement, but you’re right—they don’t have that crisp look unless you really commit to a certain style. Haven’t used backer rod behind trim... seems like a lot for what’s basically a cosmetic crack, but maybe it’d help with bigger gaps.
Honestly, the only thing that made a real difference for me was using flexible caulk instead of painter’s caulk. It moves more with the wood and hasn’t cracked (yet). Still not perfect, but better than before.
I do think air leaks and drafty spots behind the trim play a part—every time I pull off old casing, there’s gaps and cold air coming through.
That’s been my experience too, especially in older homes where the original builders didn’t really worry about air sealing. I’ve pulled off trim in a couple of rooms and found everything from big gaps to random bits of newspaper stuffed in there. One spot behind my living room window was letting in enough cold air that you could feel it if you stood close during January.
I’m with you on flexible caulk helping more than painter’s caulk. The regular stuff just seems to crack right along with the wood, especially when temps swing a lot. But even with flexible caulk, I still get some movement at the mitered corners. I wonder if it’s partly because the wall framing itself shifts a bit—my house is from the late ‘50s and nothing is really square anymore.
I tried butt joints on a basement window, mostly because I was tired of fussing with miters that never lined up after a season or two. They’re definitely less obvious when they move, but I agree—they don’t have that “finished” look unless you’re going for something pretty utilitarian or craftsman-y. I’ve seen some folks add a little detail molding over the joint to dress it up, but then you’re adding more seams.
Has anyone tried using foam tape or something similar behind the trim before reinstalling? I’ve only used spray foam for bigger gaps, but it can be messy and hard to control. Backer rod feels like overkill unless you’re dealing with a huge gap, but maybe there’s a middle ground.
Honestly, I think a lot of it comes down to how much effort you want to put into sealing up those drafts versus just accepting a little seasonal movement. My partner jokes that our house “breathes” more than we do, and honestly, she’s not wrong...
I hear you on the seasonal movement, but honestly, I still lean toward miters—at least for the main living spaces. Yeah, they can pull apart a bit, but I’ve found if you take the time to really square things up and use a good wood glue at the joint (not just caulk), they hold up better than folks give them credit for. Butt joints are easier, but to me they always look like a shortcut unless you’re matching existing craftsman trim. Foam tape behind the trim sounds interesting, but I’d worry it might make the casing sit proud or feel spongy. I guess every house has its own quirks, though...
Funny, I’ve seen both joints go sideways when the humidity swings, but I’m with you—miters just look cleaner in most rooms. I did my sister’s living room last winter, and even after a year, the miters are still tight. Used biscuits and Titebond, which helped a ton. Butt joints always remind me of quick rental flips... not really my vibe unless it’s original to the house. Never tried foam tape behind trim—seems like it’d mess with the fit more than help, honestly.
I hear you on the miters looking cleaner. I did all the window trim in our den with miters a couple years ago, and they’ve held up pretty well—though I did notice one corner open up just a hair last summer when it got really humid. I used glue and brad nails, but didn’t mess with biscuits. Butt joints just remind me of those old 70s houses, honestly… not my favorite look unless you’re matching existing trim. Foam tape seems like it’d make things too squishy and maybe even harder to get a crisp line.