Why Older Glendora Homes Have Window Problems

Mid-century sashes, original single panes, and decades of Southern California sun all take a toll. Here’s what’s normal for an older local home, what’s an easy fix, and what’s worth replacing.

Glendora, La Verne, Claremont, and the surrounding foothill towns are full of beautiful older homes — Craftsman bungalows, post-war ranches, mid-century tracts, and Spanish-revival classics. We love working on them. But the windows in these homes share a predictable set of problems, and after 37 years on White Avenue we can usually name the issue before we’re through the front door.

Here’s what’s going on with older home windows in our area, and how to think about each one.

Original single-pane glass

Many local homes still have their original single-pane glass. It’s not a defect — it just predates the energy codes that made double-pane standard. Single panes let more heat in during summer and out during winter, and they do little for street noise. The good news: you usually don’t have to replace the whole window to upgrade. Depending on the sash, we can often fit insulated or low-E glass into the existing frame. What that runs is covered in our 2026 glass replacement cost guide.

Seals that all fail at once

If a previous owner upgraded to double-pane windows in, say, the early 2000s, those sealed units are now two decades old — and they tend to fail in clusters, fogging up within a few years of each other. It looks alarming when three windows haze over in one summer, but it’s normal aging. Each one is usually a glass-only swap, not a full replacement; we explain how to tell in foggy double-pane windows: repair or replace?

Sticking and painted-shut sashes

Decades of repainting, humidity swings, and settling leave older wood sashes sticking, dragging, or painted shut entirely. Most of these are fixable — sometimes even a DIY job. We walk through the first things to try in stuck windows: 5 fixes to try first before you call anyone.

“Older windows aren’t disposable. Nine times out of ten we can save the window your house was built with.”

Worn balances, ropes, and hardware

The mechanical guts of an old window wear out: sash cords snap, spiral balances lose tension, crank operators seize, and latches stop catching. These are bread-and-butter window repairs — we keep common hardware on hand and can match a lot of the obsolete stuff, so a window that “they don’t make parts for anymore” often isn’t a lost cause.

Brittle, sun-rotted screens

Original screens on older homes are usually sun-baked to the point of crumbling. If the frames are still straight, a re-screen brings them back for a fraction of replacement — see re-screen or replace your window screens? for how to tell.

Repair or replace? It depends on the home

For a character home where the windows are part of the architecture, we lean toward preserving and repairing. For a home where the original windows are beyond saving — or where comfort and energy bills matter more than period accuracy — modern replacement windows are the better long-term value. There’s no one right answer; it depends on your home, your budget, and how long you plan to stay.

Older doesn’t mean hopeless

The windows in an older home are almost always more fixable than they look. Before you assume you need a full replacement, get a second opinion from someone who repairs as often as we replace. We’ve been doing exactly that for the East SGV’s older homes since 1989.