Tackling new windows: where do you even start with DIY tutorials?

I’m curious if your windows are original to the house or if they’ve been replaced before. Sometimes you pull off the trim and find all sorts of weird stuff - like shims stacked with old newspapers or even hidden rot. Did you already poke around to see what you’re up against, or are you waiting until you’re ready to start?

Sometimes you pull off the trim and find all sorts of weird stuff - like shims stacked with old newspapers or even hidden rot.

I get what you mean, but honestly, I think it’s risky to start poking around too early unless you’re ready for a project to spiral. I waited until I had all my tools and supplies lined up, just in case I ran into rot or insulation issues. My house is 1960s, so I expected the worst, but surprisingly, the framing was solid - just a ton of random filler material. Sometimes you can overthink it and end up opening a can of worms before you’re ready.

I hear you - sometimes it’s tempting to just dive in, but man, one loose piece of trim and you’re suddenly patching drywall or tracking down weird insulation from the 70s. I always keep a shop vac handy just for the mystery debris. Having everything ready makes those surprises way less stressful, for sure.

I always keep a shop vac handy just for the mystery debris.

I’ve seen more weird window frames than I care to admit - old houses are like a box of chocolates, except half the chocolates are just rot and mystery nails. You’re right about needing a second set of hands for the heavy lifting, especially if your windows are big or on a second floor. I usually prop up the new window with shims and a bucket or two when I’m solo, but it’s a bit of a circus act.

For tutorials, I actually like “This Old House” on YouTube. They’re not perfect, but they tend to show the ugly stuff - like dealing with wavy plaster or frames that aren’t even close to square. It’s not always step-by-step, but you see enough real-world mess to get the gist.

Biggest tip: measure everything three times, and expect to find something gross behind the trim. Oh, and keep a pry bar handy - you’ll need it.

That’s the thing about old houses - there’s always some surprise hiding in the walls or under trim. I’ve had to deal with window openings that were so out of square, I started questioning if my level was broken. “This Old House” is solid, but sometimes I’ll skim forums or Reddit for those weird real-life curveballs you never see in polished tutorials. And yeah, shims are your best friend…unless you drop one out a second-story window, which I may or may not have done more than once.

Man, you nailed it about old houses throwing curveballs. I thought I was ready for anything after watching a pile of “This Old House” episodes, but nothing preps you for a window opening that’s off by almost an inch on the diagonal. My 1920s place had me second-guessing every tool in my kit, and yeah, shims are non-negotiable. Dropped a couple myself - one even landed in the neighbor’s flowerbed, which was a fun conversation to have.

I get what you mean about polished tutorials glossing over the weird stuff. Most of them never mention what to do when you pull off the trim and find half the framing is just... missing. That’s where forums like this are actually useful - real people with real messes.

One thing I’d add: don’t stress if you end up with a little extra caulk or trim to cover gaps. Square is kind of a myth in these old places. As long as the window operates and you get decent insulation, it’s a win. I spent way too long chasing “perfect” and realized good enough is sometimes all you get.

If you haven’t already, check your local code about egress or tempered glass requirements, especially for basement or bathroom installs. I got tripped up on that once - ended up swapping a whole unit after the inspector flagged it.

Anyway, you’re definitely not alone with the shims or the surprises. It’s half the fun, right? Or at least, that’s what I keep telling myself when I’m prying off 80-year-old lath for the third time...

Man, the “square is a myth” line cracked me up - truer words. My place is a 1938 “fixer-upper” (translation: everything’s wonky), and I swear every window install turns into a geometry pop quiz. I’ve learned to just keep a bucket of shims handy and not sweat it when things don’t line up like the YouTube pros say they should. Half the tutorials make it look like you’re working with fresh lumber and laser levels, not 80-year-old timber that’s seen some things.

You nailed it about caulk and trim being your best friends. I used to obsess over every tiny gap, but after my third window, I realized nobody’s crawling around with a square checking my work except maybe the cat. As long as it’s draft-free and opens without a crowbar, I call it a win.

Had to laugh at the code bit too - been there. Failed an inspection once because I didn’t realize the bathroom window needed tempered glass. That was a fun redo... not. Sometimes it feels like these old houses are just trolling us for fun.

Yeah, those YouTube folks always seem to be working in houses built last week, don’t they? I swear, if I had a dollar for every time I tried to follow a “simple” window tutorial only to realize my opening is more parallelogram than rectangle, I could probably pay someone else to do the work.

You’re spot on about shims and caulk. I used to think shims were just for pros, but now I treat them like seasoning - add ‘em until it tastes right. And don’t even get me started on trim. Whoever invented wide trim deserves a medal. Covers a multitude of sins.

I hear you about the code stuff too. I once got dinged for not having the right egress size in a basement window. Had to rip the whole thing out and start over. It’s like the house and the inspector are in cahoots just to keep us humble.

Honestly, I think the best lesson with these old places is learning to let go of perfection. As long as it keeps the weather out and doesn’t look like a funhouse mirror, that’s a win in my book. The only “square” in my house is the one on my tape measure - and even that’s questionable.

Funny thing, though, the quirks start to grow on you after a while. I used to curse every crooked stud, but now I kind of like that nothing’s cookie-cutter. Makes it feel like a real home, not just another box. Probably helps to have a sense of humor (and a forgiving cat).

Man, the first time I tried to put a new window in my own 1920s place, I thought I was losing my mind. Nothing was level, nothing was plumb, and I swear the opening was shaped like a potato chip. Those “easy” YouTube demos must be filmed in houses where the wood still smells like the lumber yard. Shims basically became my best friend - sometimes I think there’s more shim than frame in my kitchen window. And you’re right about wide trim... covers up a lot of “creative” problem solving. Honestly, as long as it opens and closes and keeps the rain out, I call it a success.

“Shims basically became my best friend - sometimes I think there’s more shim than frame in my kitchen window.”

That line about shims is hitting a little too close to home. I swear, after tackling two windows in my place (1927 bungalow, so you know the drill), I started to wonder if the house was built by someone who’d never heard of a level. I get what you mean about YouTube tutorials - do any of those folks ever show what to do when your rough opening looks like it was carved out with a hatchet? I always watch those videos and think, “Where’s the bit where everything goes sideways and you have to run out for more shims or, worse, new trim?”

Here’s what gets me: how do you really know when “good enough” is actually good enough? I mean, yeah, the window closes, no rain leaks in, but then winter hits and suddenly there’s a breeze strong enough to rattle your teeth. Is that just par for the course with old houses, or did I miss some secret step? I’ve tried all kinds of caulk and foam, but it still feels like patchwork sometimes.

And about that wide trim - funny how “historic charm” usually means “let’s cover up the evidence.” But I guess that’s part of the fun? Or at least, it keeps things interesting. Wouldn’t mind knowing if anyone else just kind of shrugs and calls it done once it passes the basic tests. Or am I just getting lazy in my old age...

“Here’s what gets me: how do you really know when ‘good enough’ is actually good enough? I mean, yeah, the window closes, no rain leaks in, but then winter hits and suddenly there’s a breeze strong enough to rattle your teeth.”

Man, I hear you on that one. I’ve got a 1910 rowhouse and the first time I replaced a window, I spent way too long fussing with the level, then finally just gave up and made friends with a mountain of shims and a tube of Great Stuff. It looked okay until January, then it was draft city. Turns out, the “good enough” test for these old places is a moving target.

What helped me was picking up a cheap infrared thermometer and checking for cold spots around the frame after installation. If I found a big temp drop, I’d go back and hit it with more low-expansion foam or tack on some weatherstripping. Doesn’t always look pretty under the trim, but it actually made a difference.

I’m convinced that wide trim isn’t just for style - it’s the original DIY hack for hiding sins. If the window opens, closes, and you don’t feel a breeze, that’s honestly a win in my book. Maybe not perfect, but these houses weren’t ever really airtight to begin with.

That’s actually a really clever idea with the infrared thermometer - I hadn’t thought of that. I just finished my first window swap last month, and honestly, I kept second-guessing every step. The videos make it look so straightforward, but in real life, nothing’s square and the gaps are just… everywhere.

Here’s what I did: after getting the new window in and shimming it until it looked level-ish, I ran a bead of caulk outside and used low-expansion foam inside. But I wasn’t sure how much foam was too much, or if I was missing spots. The trim does hide a lot, but I still worry about cold sneaking in behind the scenes.

I’m starting to think “good enough” is less about perfection and more about not feeling a draft or seeing water stains after a storm. Still, I wonder if there’s something I’m missing - like, should I be sealing the sill differently, or is there some trick to making old frames less wonky? Every tutorial seems to gloss over those weird problem spots. Maybe that’s just old houses for you...

Yeah, those tutorials always skip the weird, crooked spots that make old houses such a pain. I’ve seen so many “just shim and foam” videos, but nobody talks about what to do when the sill is bowed or the frame’s out of plumb by half an inch. Did you use any sill pan or flashing under the window? That’s one thing I see missed a lot - water will find its way in eventually if the sill isn’t sealed right. As for foam, less is usually more; too much can actually bow the frame. I usually run a bead and then check after it sets - sometimes you have to top it up, sometimes you have to trim it back. It’s a lot of guessing, honestly. Old houses just don’t make it easy…

I’ve seen so many “just shim and foam” videos, but nobody talks about what to do when the sill is bowed or the frame’s out of plumb by half an inch.

That’s exactly the problem I ran into with my 1920s place. The sill was so uneven I ended up ripping some shims down to weird angles just to get the window to sit level-ish. I did use a sill pan - honestly, after seeing how much water damage was under the old window, I didn’t want to risk it. It’s not pretty, but at least it should keep things dry. Foam is such a pain too… I always end up trimming way more than I expected.

That’s the part nobody warns you about - old houses just don’t play by the rules. I had to deal with a sill that dipped almost 3/8" in the middle, and honestly, it made me wonder how much air I was losing in winter before I fixed it. Did you notice any drafts after installing? I found that even with foam, if the frame’s really out of whack, there are still little gaps unless you’re super careful. Makes me question if those “quick install” videos ever deal with real-world houses or just new construction...

Honestly, I’ve found that with older homes, sometimes you just have to accept a little imperfection. Foam works, but if the sill’s really out of level, I’ll sometimes use a backer rod or even custom-cut shims to get a tighter seal. Quick install videos rarely show the messier realities - like when you pull out an old window and half the frame crumbles or nothing’s square. Still, with enough patience and a few tricks, you can usually get it pretty airtight. It just takes more time than those tutorials suggest.

I get what you’re saying about embracing a bit of imperfection, but I’m not sure I’d settle for “pretty airtight” if you’re already going through the trouble of replacing windows. There are some newer expanding tapes (like illbruck or Rothoblaas) that can compensate for uneven gaps and irregular frames way better than foam or just shims. I tried them on my 1920s place - nothing was square, and the old brick was a nightmare - but the tape compressed into all the weird voids and didn’t crumble like foam sometimes does when things shift.

Also, I know it’s tempting to just fill gaps and move on, but if the sill is really far out of level, sometimes it’s worth biting the bullet and rebuilding part of it. Otherwise, you’re just sealing in problems that’ll show up later. It adds time, yeah, but I’d rather do that than deal with drafts or water leaks down the line.

DIY videos definitely gloss over that stuff. The “just slap in some foam” approach doesn’t always cut it, especially in old houses where nothing is standard. Anyone else tried those tapes or gone all-in on sill repairs?

Expanding tapes are a huge step up from foam, especially in old houses where every frame seems to have its own personality. I’ve used the illbruck stuff - pricey, but honestly worth it for weird gaps. Still, even the best tape won’t save you from a crooked sill. I’ve had to bite the bullet and rebuild more than one, and yeah, it’s a pain, but fixing water damage later is way worse. DIY videos make it look like a five-minute job... they never show the three hours with a chisel and a level.

Yeah, those DIY videos crack me up - blink and suddenly the window’s square, sealed, and trimmed. Meanwhile, I’m on my third trip to the shed for another tool I didn’t know I’d need. I’ve tried expanding tapes too (not illbruck, but similar), and they do help with the weird gaps in these old frames. But if the sill’s warped, no amount of tape is gonna fix a draft. I learned that the hard way after a winter where my living room felt like a wind tunnel. Sometimes you just gotta accept it’s not a quick fix.