I've never tried the painter's tape trick, but it sounds interesting. Usually, I just stick with rubber glazing blocks because they're pretty foolproof. One thing I've learned the hard way—make sure your window opening is actually square before you start shimming. Measure diagonally corner-to-corner first; if it's off, you'll be fighting it the whole time. Ask me how many windows I installed crooked before figuring that out...
"Usually, I just stick with rubber glazing blocks because they're pretty foolproof."
Rubber glazing blocks are solid, but honestly, I've found composite shims even easier to work with. They don't compress or shift over time like rubber sometimes can, especially in hotter climates. Learned that after a few callbacks from customers noticing gaps later on... Also, totally agree about checking diagonals first—nothing worse than realizing halfway through that your opening's off-square.
Interesting point about composite shims, hadn't thought of that angle before. Have you ever run into any issues with them being a bit brittle in colder temps? I remember helping a buddy install some windows last winter, and a couple composite shims snapped on us—granted, could've just been our luck or the brand we used. Rubber blocks might compress a bit, sure, but at least they're forgiving when things aren't perfectly aligned... Thoughts?
"Rubber blocks might compress a bit, sure, but at least they're forgiving when things aren't perfectly aligned..."
Yeah, that's a solid point. I've used composite shims quite a bit and haven't had many issues myself, but I can definitely see how cold weather could make them brittle—plastics and composites tend to get finicky in freezing temps. Rubber blocks do have that nice "give" factor, especially if you're working solo and can't always nail alignment perfectly the first try. Might be worth keeping both handy depending on conditions...
I've done a fair share of vinyl window installs myself, and honestly, rubber blocks saved my sanity more than once. Composite shims are great when everything's cooperating, but if you're dealing with an older house (like mine) where nothing's ever square, that little bit of flex from rubber can be a lifesaver. Just make sure you don't over-compress them—snug is good, squished flat isn't. Learned that one the hard way...
"Just make sure you don't over-compress them—snug is good, squished flat isn't."
Haha, been there myself. Rubber blocks are definitely underrated, especially with older houses. Another thing that's saved me a ton of headaches is keeping a small pry bar handy—sometimes you just gotta gently persuade things into place. And when nothing's cooperating, stepping away for a coffee break has probably preserved my sanity more than any tool in my box...
Good call on the pry bar—definitely a lifesaver. Another thing I've found helpful is dry-fitting the window first and marking any tight spots with a pencil. That way, you can sand or shim exactly where needed before committing to the install. And don't underestimate the power of a good level—checking multiple times as you go can save you from having to redo things later. Trust me, nothing worse than stepping back and realizing it's slightly off... been there, done that.
Dry-fitting saved me a ton of headaches too, but one thing I learned the hard way: don't trust your eyes alone. Last summer, I thought everything looked great after marking and sanding down tight spots, but the window still felt off when I went to install it. Turns out my frame was slightly warped—barely noticeable until I grabbed the level. Had to backtrack and shim more than I'd planned...lesson learned. Anyone else run into sneaky issues like that?
Yeah, been there myself. One thing I've learned is to always check diagonals, not just level and plumb. Had a similar issue where everything looked spot-on until I measured corner-to-corner and realized the frame was slightly out of square. Ended up having to shim and tweak way more than I wanted. Now I always double-check diagonals before committing—saves a lot of frustration later on.
Good call on the diagonals—I overlooked that once and paid for it later. Another thing I've found helpful is dry-fitting the window first without any sealant or screws. Just pop it in place, shim lightly to hold it steady, and then check everything—level, plumb, diagonals, even how it opens and closes. If something's off, you'll catch it early and save yourself from scraping off caulk or pulling screws later... trust me, that's no fun.