new windows leaking - bad install job or faulty windows?

Had something similar happen a couple years back when we replaced ours. Windows looked great, seemed solid, but first heavy rainstorm and boom - water pooling right on the sill. Turned out the installers rushed the flashing and sealing around the frames. Honestly, even high-quality windows can leak if the install isn't spot-on. I was skeptical at first too, thinking maybe the windows themselves were faulty, but after having another crew redo the sealing properly, haven't had a single drop come through since.

Not saying factory defects don't happen - they definitely do - but from what I've seen and heard, installation issues are way more common. Might be worth having someone else take a quick look before you go chasing warranty claims with the manufacturer.

Had a similar headache myself last spring. Thought I'd bought lemons because the windows were pricey and supposedly top-notch, but nope - it was all about the flashing and sealing. Installers skipped steps on the waterproofing membrane around the frames, and water found its way in pretty quick. Once we got someone else to redo it properly, problem solved. I'd definitely get a second opinion on the install before assuming it's the windows themselves... installation shortcuts are way more common than faulty products, unfortunately.

"installation shortcuts are way more common than faulty products, unfortunately."

Yeah, totally agree with this. When we replaced our windows a couple years back, I was convinced we'd gotten defective units because of some leaks during heavy rain. Turns out the installers had rushed through sealing the top edges and corners - basically skipped proper flashing altogether. Had another contractor come out to inspect, and he pointed out exactly where they'd cut corners. Once we got that sorted, zero issues since.

One thing I'd add is to check if your warranty covers installation errors or just product defects. Ours didn't cover poor workmanship, so we ended up paying extra to fix someone else's sloppy job... frustrating, but lesson learned. Anyway, definitely worth getting a second set of eyes on it before blaming the windows themselves.

Had a similar issue last spring. Here's what I'd do first: grab a hose and spray around the window edges from outside, starting low and working upward slowly. Have someone inside watching closely to pinpoint exactly where water comes through. If it's around the frame or corners, probably installation. If water somehow seeps through the glass or sash itself, could be defective windows. But yeah, installers cutting corners is way more common.

One thing I’d add before the hose test: take photos or video during the next real storm, then have the installer inspect the exterior drainage paths. I once had water coming through because the weep holes were blocked, not because the glass or seal failed. An incorrectly sloped sill pan can also send water indoors. I’d give the installer written notice and let them inspect before anyone alters the flashing, since that may matter for the workmanship warranty.

Before anyone opens up the flashing, could the installer provide:

- The manufacturer’s installation instructions for that specific window model.
- A written diagnosis stating whether the leak is through the window unit, or through the sill pan, flashing, weep holes, or surrounding seal.
- Photos of any failed or missing waterproofing details.

Since blocked weep holes and a badly sloped sill pan can look like a defective window from inside, having that documented should help separate a product warranty issue from workmanship. It may also prevent the installer from simply resealing the visible edge without finding the actual water path.