Almost nobody replaces a window a moment too early — they replace it about five years too late, after paying for two repairs that were never going to hold. The signs you need new windows are usually there long before the decision gets made. They just get filed under “that’s always been like that.” After 36 years of working on windows across the San Gabriel Valley, we’ve learned that homeowners rarely need convincing to replace — they need someone honest enough to tell them which problems are worth fixing and which ones aren’t.
Here are the seven that point to replacement, the three that don’t, and how to tell which camp your window falls into before you spend anything.
The 7 signs you need new windows
1. Fog or moisture sealed between the panes
If your dual-pane window looks hazy from the inside and wiping does nothing, the insulating seal has failed and moisture is living in the gap. That window has stopped doing the job it was built for, and there’s no sealing it back up in place. The good news is you may only need the glass unit replaced, not the whole window — we walk through both routes in foggy double-pane windows: repair or replace?. If it’s happening to several windows at once, the whole set is aging out together.
2. It won’t open, won’t stay open, or won’t lock
A window that fights you is more than an annoyance — it’s an egress and security problem. Plenty of sticking windows are a cheap fix: dirty tracks, tired balances, a warped screen frame, a lock out of alignment. Try the five fixes for a stuck window first. But when the sash itself has racked out of square, when the frame has bowed, or when the hardware is a discontinued 1970s part no one stocks, you’re maintaining a window that has already given up.
3. You can feel the draft — and hear the street
Stand next to a closed window on a windy evening and hold the back of your hand near the edges. Air movement means the seal or the frame has opened up. Noise is the same signal in another form: single-pane glass barely slows sound, so if you’ve started noticing traffic, leaf blowers, or the 210, the glass is telling on itself. New weatherstripping buys you a season. If you’ve replaced it twice, the frame is the problem.
4. Rot, soft wood, or crumbling putty in the frame
Press a screwdriver handle into the wood at the bottom corners of the sash and the sill. If it gives, that window is past repair — and the damage often runs into the framing behind it. Older stucco-and-wood homes here are especially prone to it, which is one of the recurring themes in why older Glendora homes have the window problems they do. Metal frames don’t rot, but they pit and corrode, and the result is the same: nothing left to seal against.
5. The sun-facing rooms cook every afternoon
If the west side of your house runs five to ten degrees hotter than the rest of it from 3 p.m. on, your glass is a big part of why. Old clear single-pane glass lets solar heat pour straight in. That doesn’t automatically mean replacement — solar screens, film, and shade are cheaper first moves, and we cover the full ladder in how to keep your house cool in SoCal heat. But if you’ve already done those and the room still cooks, the glass itself is the ceiling on your comfort. Our take on whether the upgrade pays is in are Low-E energy-efficient windows worth it?
6. You still have original single-pane aluminum
Homes across Glendora, San Dimas, Covina, and Azusa built between the 1950s and the early 1980s are full of aluminum sliders with a single sheet of glass in them. Aluminum conducts heat and cold beautifully — which is exactly the problem — and the frames sweat on cold mornings. These windows aren’t broken so much as obsolete, and swapping them is the single biggest comfort change most of these houses can make. What that conversion actually buys you is laid out in single-pane to dual-pane.
7. The glass keeps breaking, or it’s broken now
One broken pane is an accident, and replacing the glass is usually the right answer. A pattern is different. Glass that cracks without impact — a clean line appearing overnight, or the same window failing twice — is often a frame under stress: settled, out of square, or pinching the glass. Replacing the pane in a frame like that is buying the same problem again in six months.
A fast field test
Ask two questions about the window in front of you. Is the frame sound and square? Does the hardware still exist? If both answers are yes, almost everything else is repairable — glass, screens, rollers, balances, weatherstrip. If either is no, you’re patching a window that has already reached the end of its life.
3 problems that are not replacement signs
These come up constantly, and none of them require new windows:
- Condensation on the room-side surface of the glass. That’s humidity in your house meeting cold glass, not a broken window. Only moisture trapped between the panes indicates failure — the three-way diagnosis is in window condensation: inside, outside, or between panes?
- Torn, saggy, or missing screens. A screen is a consumable part, not a window. Re-screening a frame is one of the least expensive things we do — see re-screen or replace? before you let anyone quote you a window over it.
- A patio door that drags. Nine times out of ten that’s worn rollers and a dirty track, not a dying door. Start with sticky sliding door roller fixes.
The right question isn’t “how old is this window?” It’s “is the frame still sound, and can I still get parts?”
Repair or replace, side by side
| What you’re seeing | Usually a repair | Usually a replacement |
|---|---|---|
| Fogged dual pane | New insulated glass unit in a sound frame | Multiple windows fogging + aging frames |
| Hard to open | Tracks, balances, rollers, hardware | Sash or frame out of square; no parts available |
| Drafts and noise | Weatherstrip, re-glaze, re-seal | Gaps at the frame itself, or single-pane glass |
| Damaged frame | Surface repair on sound wood | Soft or rotted wood; corroded metal |
| Broken glass | Cut and install a new pane | Repeat breakage from a stressed frame |
What replacing a window actually involves
There are two paths, and the difference matters more to your budget than the brand on the sticker. A retrofit (or insert) replacement sets a new window inside the existing frame, leaving your stucco and interior trim alone — faster, cleaner, and the right call when the frame is sound. A full-frame replacement takes everything back to the rough opening; it costs more and touches the finishes, but it’s the only honest answer when there’s rot or water damage behind the frame.
You don’t have to do the whole house at once, either. Doing the sun-facing or worst-performing elevation first is a completely normal way to spread the work out. And where safety glazing is involved — near doors, in bathrooms, close to the floor — building code can require tempered glass in the replacement even if what’s there now isn’t; your city’s plan checker has the final word.
We don’t publish a flat per-window price, because a 3-by-4 retrofit slider and a full-frame picture window are not the same job. Size, type, glass package, and frame condition all move the number — the same variables we walk through in our glass replacement cost guide. Text a photo of the window to (626) 335-2900 and we’ll tell you honestly whether it’s a repair or a replacement before anyone measures anything.
The bottom line
Windows rarely fail all at once. They fog, they stick, they leak air, and then one day you realize you’ve been living around them for years. If you’re seeing one of the seven signs above, get an opinion — and if you’re seeing three or more on the same window, you already have your answer.
Glendora Window has been repairing and replacing windows in this valley since 1989, out of our shop at 1782 N White Ave in La Verne. We do window repair, glass replacement, and new window installation for homes in Glendora, La Verne, San Dimas, Claremont, Covina, Azusa, Pomona, and Upland — and we’ll tell you when a repair is the better buy. Request a free estimate or call (626) 335-2900.
