- I totally get what you mean about butt joints looking dated. I tried miters in our living room and used just glue and nails too—one corner did separate a bit when it got muggy.
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Same thing happened to me. I’ve heard adding splines or biscuits helps with that, but I haven’t tried yet.“I did notice one corner open up just a hair last summer when it got really humid.”
- Foam tape seems risky for trim…feels like it’d squish and mess up the lines, especially if you’re going for crisp, modern corners.
- If you’re after clean lines, miters still look best to me, but they definitely need extra attention in humid spots.
- Been through both butt and miter joints in my 70s ranch—neither’s perfect, but miters look way sharper, especially if you’re after that modern vibe.
- Humidity’s the real enemy. I had a mitered corner pull apart just enough to bug me every time I walked past. Ended up re-gluing and adding a couple tiny brads... held up better, but still not flawless in July.
- Butt joints are definitely easier and more forgiving if your walls aren’t dead square (and let’s be honest, when are they?). But yeah, they can look a bit old-school, especially on painted trim.
- Tried biscuits once. Bit of a hassle for window trim, but it did help keep things tight. Not sure I’d bother unless you’re a perfectionist or have a lot of movement in your house.
- Foam tape? I’d skip it—seems like a shortcut that’ll haunt you later.
- If you want crisp corners, take your time with miters, use a good glue, maybe even clamp overnight. Caulk hides a lot, but only up to a point.
In my experience, nothing beats patience and a little wood filler for those inevitable gaps. Murphy’s Law applies to trim work too...
I’ve wrestled with this exact choice on my own place (1963 split-level, walls nowhere near square). Here’s how I usually break it down:
If you want the modern, “clean lines” look, miters are tough to beat. But man, they’re fussy. I’ve had corners split open after a humid summer, even after gluing and nailing. If you go that route, here’s what’s worked for me:
1. Dry-fit everything first—don’t trust your saw angles until you see it on the wall.
2. Use a decent wood glue (Titebond III has been my go-to) and clamp if you can.
3. Sink a couple finish nails or tiny brads through the miter to help hold it while it dries.
4. Once it’s up, fill any gaps with wood filler and sand smooth before painting.
Still, if your walls are wavy or out of square (mine definitely are), miters can highlight that in a way butt joints just don’t. Butt joints are way more forgiving—just square off one piece against the other and call it good. They’re not as “designer,” but they hold up well and are easier to fix if something shifts later on.
Tried biscuits too, but honestly felt like overkill for trim—maybe worth it if you’ve got a ton of movement or just want to impress yourself.
One trick I’ve picked up: after caulking, run a damp finger along the joint for a cleaner line. Doesn’t fix bad cuts, but hides little issues.
I still lean toward butt joints in rooms where nobody’s looking too close (like basement windows), and miters in the main living areas where I want things sharp—just gotta accept they might need touch-ups every now and then.
Humidity is always lurking... Murphy’s Law for sure. Anyone else have luck with pocket screws on window trim? Never tried it myself—wonder if that’d solve some of these headaches or just make more holes to patch later...
Butt joints are way more forgiving—just square off one piece against the other and call it good.
Man, I hear you on that. I’ve done mitered corners in some older houses and it’s like chasing your tail—one gap closes, another opens. Butt joints might not win beauty contests, but they don’t split on me every time the weather changes. Tried pocket screws once and just ended up patching more holes... felt like I was fighting the trim instead of installing it.
I get the appeal of butt joints—especially in older houses where nothing’s ever square and you just want to get the trim up without a fight. I’ve been there, chasing my own tail with those mitered corners that never seem to line up, especially when the walls have shifted a bit over the years. But I gotta say, after messing around with both, I still lean toward miters for most of my windows, even if it takes a bit more patience.
Here’s what changed my mind: I did a room with butt joints because I was in a hurry and figured “good enough.” Looked fine at first. Then, about six months later (after our first real winter), those joints started to show little gaps. Just hairline stuff, but enough for me to notice every time I walked by. Maybe it’s our crazy swings in humidity, but it bugged me. With miters, yeah, you’re fighting the angles and sometimes you’ve gotta break out the wood filler or caulk... but if you glue and nail them right and maybe even clamp them for a minute or two, they seem to hold together better when the trim wants to move.
Not saying miters are perfect—definitely not in an old house where nothing’s straight. Sometimes I cheat and use a bit of back bevel on the cut or scribe one piece to fit. It’s slower, but it gives a cleaner look when you’ve got guests over (or when my wife’s doing her “inspection”). Butt joints are easier to patch if things go south, though. I’ll give you that.
Pocket screws were a disaster for me too—made a mess of soft pine trim and I ended up filling more holes than I started with. These days, I just stick to glue and finish nails for corners.
Guess it comes down to what bugs you more: the work up front or the little gaps later on. For me, I’d rather curse at my saw for an hour than stare at open seams all winter... but ask me again after my next project and maybe I’ll be back on the butt joint train.
I totally relate to the frustration with old houses and their not-so-square corners. My place was built in the 40s, and it’s like every wall and window frame has its own personality—nothing lines up the way you’d hope. I’ve tried both approaches, and honestly, I keep going back and forth depending on my mood or how much patience I have that day.
Miters do look sharp when you get them right. I’ve had the same experience with butt joints looking fine at first, then those tiny cracks show up when the seasons change. Humidity here swings a lot too, and I notice the gaps more in the winter. I’ve started getting picky about how I glue and clamp miters, and sometimes I’ll even pre-fit all the pieces before nailing anything down. It’s a pain, but the joints seem to stay tighter that way.
That said, I don’t think butt joints are all bad. If you’re painting the trim and you’re okay with a little caulk now and then, they’re way less hassle up front. I did a rental unit with all butt joints just because I needed to bang it out quickly, and honestly, the gaps didn’t bother me as much since I knew I’d be touching up paint every couple years anyway.
I’ve never had much luck with pocket screws on trim either—seems like overkill for something that’s mostly decorative, and like you said, the holes are a pain to fill. I’ve had better luck just using a brad nailer and some good wood glue.
One thing I’ve tried that helped with old, out-of-square corners is making a test cut and sneaking up on the angle with a hand plane or sanding block. Takes a little more time, but it’s less frustrating than trying to force a perfect 45 onto a wonky wall.
In the end, I guess it’s about what bugs you more—the work or the little imperfections that pop up later. I’m usually more annoyed by gaps than by the extra time it takes to get miters right, but there are definitely days when I just want to get it done and move on.
I get where you’re coming from with miters looking cleaner, but I’ve gotta push back a bit on the idea that butt joints are always the quick-and-dirty option. In some of these old houses, especially when the walls are way out of square, I’ve actually found a well-fitted butt joint with a little back bevel holds up better over time. Less visible shifting, and honestly, easier to touch up with caulk or paint down the road.
“If you’re painting the trim and you’re okay with a little caulk now and then, they’re way less hassle up front.”
Exactly—sometimes practical wins out over perfect, especially if you know you’ll be repainting anyway. Miters look great, but I’ve had them open up more than butt joints when the humidity swings wild. Just my two cents from too many old window frames...
“Miters look great, but I’ve had them open up more than butt joints when the humidity swings wild.”
Couldn’t agree more about old houses and shifting walls. I’ve chased miter gaps with caulk every spring—never seems to last. Butt joints with a back bevel just ride out the movement better, especially if you’re dealing with plaster that’s seen better days. Sure, miters look sharp on new builds, but in a 1920s place like mine? Practical wins out every time.
- Had the same battle with miters in my 1948 place—especially on the north side where the sun barely hits.
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Yep, that yearly caulk routine gets old fast.“I’ve chased miter gaps with caulk every spring—never seems to last.”
- Tried switching to butt joints last time I re-did the trim in the laundry room. Honestly, way less hassle—no more staring at that hairline crack every time the weather shifts.
- Noticed with butt joints (back bevel helped), even when the wall flexed a little, the joint stayed tight. Miters just seem unforgiving if anything moves out of square.
- Only thing I miss is that sharp look miters give. But after patching and repainting for years, I’ll take “good enough” over perfect lines that don’t last.
- Anyone else tried splining or biscuits on miters? Wonder if that actually helps with movement or just adds work...
“I’ve chased miter gaps with caulk every spring—never seems to last.”
You’re not alone there. I spent a few years trying to keep miters tight around my kitchen windows—looked great for maybe a season, then the joints would open up just enough to bug me. Tried biscuits once, but honestly, it didn’t make much difference except for more work and sawdust. Butt joints aren’t as sharp-looking, but after a couple rounds of repainting, I started caring more about not having to fix things every year. Sometimes “good enough” really is good enough, especially in an old house where nothing’s square anyway.