- Totally agree on the aluminum flashing—used it myself and it works great, just gotta watch those edges.
- Another handy trick I've found is using old credit or gift cards as shims. They're thin, sturdy, and easy to trim down with scissors.
- Composite shims are solid too, but sometimes they're a bit thick for my liking. Cards or flashing can really help dial in that perfect fit without fussing around too much.
I've used aluminum flashing too, and yeah, those edges can bite if you're not careful. Learned that the hard way—still got a scar on my thumb from a rushed job years ago. The credit card shim trick is clever; wish I'd thought of that before tossing out a stack of expired gift cards last spring.
One thing I've done in a pinch is use strips cut from plastic milk jugs. They're thin enough to layer easily, and you can trim them down with regular scissors. Plus, they're flexible enough to slide into tight spots without cracking or splitting. Not as sturdy as composite shims, obviously, but for minor adjustments they've saved me more than once.
Composite shims are great for heavier windows or doors, but I agree they can be a bit bulky when you're trying to finesse something delicate like an older wooden window frame. Sometimes simpler really is better...
Milk jug strips, huh? Never thought of that one. I usually have a stash of old plastic blinds slats kicking around—those things are surprisingly handy for shimming smaller gaps. Easy to cut, flexible enough, and they're already flat. But now you've got me curious... anyone ever tried using old vinyl flooring scraps? Got a bunch left over from the kitchen remodel, seems like they'd be sturdy enough without being too bulky.
Vinyl flooring scraps might do the trick, but I'd worry they're a bit too thick or rigid for smaller gaps. Still, worth a shot if you've got 'em laying around anyway... worst case, back to blinds and milk jugs, right?
Vinyl flooring scraps could work in a pinch, but I agree they might be a tad too stiff for really tight spots. When I tried something similar, the rigidity was actually the problem—it didn't compress enough to really fill tiny gaps, and it just kinda sat awkwardly. Ended up looking more like a DIY mess than a clever hack, haha.
Honestly, for smaller shims or gap fillers, I've had better luck with old credit cards or gift cards. They're thinner, flexible enough to wedge into tight gaps, and you can stack 'em up if you need more thickness. Plus, who doesn't have a drawer full of expired cards lying around collecting dust?
Speaking of blinds and milk jugs... funny story—my neighbor once used cut-up pieces of an old plastic laundry detergent bottle as shims for his window install. I thought he was nuts at first, but surprisingly, it worked pretty well. The plastic was just flexible enough yet held firm once he tightened everything down. Looked a bit weird at first, but once trimmed and hidden behind the trim boards, you'd never know.
Another underrated hack I've found useful is using playing cards. They're thin enough to slide into the smallest gaps easily, and you can layer them precisely to get the exact thickness you want. Plus, they're dirt cheap and easy to trim to size.
I guess it really comes down to what you've got handy and how visible the gap is gonna be after you're done. If it's hidden behind trim or casing anyway... might as well get creative with whatever scraps you've got laying around.
"Honestly, for smaller shims or gap fillers, I've had better luck with old credit cards or gift cards."
Credit cards can work, but personally I've found they tend to slip out of place over time, especially if there's any temperature fluctuation. For tight spots, I prefer using strips cut from composite shims—they're flexible enough to compress slightly and hold their shape well. A bit pricier than playing cards, sure, but worth the peace of mind in the long run.
"Credit cards can work, but personally I've found they tend to slip out of place over time, especially if there's any temperature fluctuation."
Have you tried adding a dab of silicone caulk or adhesive to keep them from shifting around? I recently installed my first set of windows (total newbie here...) and ended up using some leftover plastic loyalty cards with a tiny bit of silicone. Worked surprisingly well, even through some pretty drastic weather changes. Composite shims sound great too, though—might give those a shot next time.
Silicone can work, but honestly I prefer painter's tape—just fold a small piece over the edge of the card to create friction. Holds surprisingly well, and it's easier to adjust later if needed. Silicone can be a pain if you ever need to reposition things...
Painter's tape is alright, but honestly, silicone isn't as bad as you're making it sound. I've used it plenty of times, and if you apply it sparingly, repositioning isn't that big of a deal. Plus, silicone gives you a tighter seal and better insulation in the long run—especially important if you're dealing with drafts or moisture issues. Painter's tape might be easier to adjust, sure, but it doesn't hold up as well over time. Had a window last winter where I tried the tape trick, and after a few months, it started slipping and peeling off. Ended up redoing the whole thing with silicone anyway. Just my two cents, but I'd rather spend a bit more time upfront and not worry about it later.
I've had mixed luck with painter's tape myself. A few years back, I tried it on a bathroom window that always fogged up and got drafty in winter. It seemed fine at first, but after a couple months, moisture started creeping under the tape and it peeled right off. Ended up redoing it with silicone, and it's held up great ever since. Silicone can be messy if you're not careful, but honestly, once you get the hang of applying it sparingly, it's worth the extra effort.