Things I wish I knew before swapping out old windows for vinyl

I underestimated how much mess the old caulk would make... if you haven’t started yet, drop cloths are your friend.

Yeah, the caulk dust gets everywhere—still finding bits months later. Something else I wish I’d known: those old brick sills aren’t always level, so shims are a must. I tried skipping them once and paid for it with a sticky window.

Funny you mention sticky windows—had the same issue, but I’m still not convinced shims are the magic bullet. On one window, even after shimming, it took some serious adjusting to get it to open smoothly. Did you notice the vinyl flexing a bit if the sill was really uneven? Sometimes I wonder if there’s a better trick for old brick houses...

Man, you nailed it with the vinyl flexing on uneven sills. I’ve seen those frames do a little dance if the brick’s out of whack—sometimes it feels like wrestling a pool noodle into a square hole. Shims help, but in these old brick houses, nothing’s ever actually level, right? I’ve had better luck sometimes using a combo of shims and those composite sill extenders, but even then, there’s usually some “creative persuasion” involved. Makes me miss the old wood windows... at least they creaked in a predictable way.

- Totally get the “creative persuasion” bit—sometimes it feels like you need a third hand just to hold everything in place while you shim.
- I’ve tried those composite sill extenders too, but in my 1920s place, the old brick just eats them up unless I backfill with spray foam or extra shims.
- Vinyl’s flex is wild compared to wood. At least with wood, you could sand or plane for a snug fit… vinyl sort of just bows and hopes for the best.
- Ever deal with water pooling under the new frames after install? I had one window that needed a custom sloped pan flashing just to keep things dry.

That water pooling issue is the stuff of nightmares—been there, wrestled with that. On my last window swap, I thought I’d done everything right, but a week later after a rain, there was a tiny lake under the sill. Ended up pulling the frame and adding a self-adhesive flashing membrane, then built up a slope with extra backer rod and sealant. Not perfect, but way better. Vinyl’s flexibility is a double-edged sword; you get some forgiveness on out-of-square openings, but it’s so much trickier to dial in a tight, weatherproof fit compared to wood. Hang in there—once you get the hang of all these little tricks, it gets (slightly) less maddening.

Man, I had that same “indoor pond” issue the first time I swapped to vinyl. Thought my caulking job was solid—turns out gravity and a bad sill angle had other plans. I swear, vinyl’s like wrestling a rubber snake. Wood at least gives you a fighting chance with shims.

That’s exactly it—vinyl just doesn’t play nice if you’re not 100% level. I remember thinking “how hard can it be?” and then spent half a day fighting to get the thing to sit flush. My old wood windows at least let me fudge things a bit with shims, but vinyl? Nope, it’s all or nothing. Still, I will say the maintenance is way easier now... just wish someone warned me about needing a laser level and a lot more patience.

I get where you’re coming from, but I’ve gotta say, I didn’t find vinyl quite as unforgiving as you did.

“vinyl just doesn’t play nice if you’re not 100% level”

Totally agree about the zero-painting perk—honestly, that alone made me forgive a lot of the quirks. I did find the leveling thing a bit trickier than with wood, but maybe my old house is just extra crooked. Ended up spending way more time shimming and double-checking than I expected. Still, once they were in, the drafts were gone and my energy bill actually dipped a bit. Worth the hassle, at least for me...

Funny you mention the shimming—my place is from the 1940s and I swear nothing’s square. Did you notice any issues with the trim after installing? I had to fudge a few corners, but like you said, no more painting and the house feels way less drafty now. Worth it, quirks and all.