Maintenance & Lifespan

7 Signs It's Time to Replace Your Windows

The Peaks & Valleys field teamWritten by the crews and inspectors on the roofs

Guide4 min readLast reviewed August 7, 2026How we research

The short answer

The tells are fog or condensation between the panes (a dead seal), drafts and cold glass, rot or soft frames from our damp, sashes that stick or are painted shut, outside noise, and rising heating bills. In the PNW, single-pane or foggy double-pane is usually worth replacing — but flashing and the sill pan matter as much as the unit.

Part of our guide to The PNW Roof Maintenance Calendar: What to Do, When, and What It Buys You.

Windows are easy to ignore until a January draft or a foggy pane makes them impossible to. In the Pacific Northwest, where the rain is constant and the heating season is long, a failing window quietly leaks heat and lets moisture work at the frame around it. The trick is reading the warning signs before the damage spreads into the wall. Here are the seven that mean it’s time to look hard at replacement.

1. Fog or condensation between the panes

This is the clearest tell there is. If you see haze, fog, or moisture trapped between the panes of glass — not on the inside surface you can wipe — the sealed insulated glass unit has failed and the insulating gas has leaked out. The window’s insulation value is gone, and no amount of cleaning brings it back. The good news: on many windows the sealed glass unit can be replaced without touching the frame or trim, so this doesn’t always mean a whole new window.

2. Drafts you can feel and cold glass

If you can feel air moving with the window shut, or the glass itself is cold to sit next to in January, the unit is leaking heat. Single-pane and failed double-pane windows can shed a real share of your heating spend. Sometimes a draft is just worn weatherstripping or a tired caulk joint — fixable on its own. But persistent drafts plus cold glass on an older window usually point at the unit itself.

3. Rot or soft frames from our damp

Press on the frame at the sill and the lower corners. If the wood gives, feels soft, or looks stained and swollen, Northwest rain has found its way in through tired glazing or failed flashing. Caught early it’s a localized repair; ignored, the rot spreads into the wall and forces a full replacement. This is the failure our climate produces more than any other, and the sill is where it starts.

4. Sashes that stick or are painted shut

Windows that won’t open, won’t stay open, or have been painted shut aren’t just an annoyance — a stuck bedroom window is an egress safety issue. Broken cranks, dead sash balances, and seized locks are often a hardware repair. But when the sash is binding because the frame has swelled or racked out of square, the frame is telling you it’s near the end.

5. Outside noise living inside

If road, traffic, or flight-path noise has become a roommate, your glass is thin. Modern laminated and multi-pane glass cuts perceived noise noticeably — genuinely sleep-changing on a busy street. Noise alone isn’t a failure, but if you’re already replacing for another reason, it’s a strong argument for a better glass package on the rooms that need it.

6. Rising heating bills with no other cause

If your heating bills are climbing and nothing else explains it, a leaking building envelope is a prime suspect, and old windows are a common weak point. Windows won’t be the whole story — but single-pane and seal-failed units are usually part of it, and they’re the part you can see and test.

7. Condensation on the inside — the wrong side

Some interior condensation in winter is normal humidity. But heavy, persistent sweating and frost on the inside surface of the glass often means the glass edge is running cold — a sign of an old conductive spacer or a failing unit — and that moisture, left to run down onto the sill day after day, is exactly what rots the frame from step 3. Wipe it, then watch where it collects.

The part most people miss: flashing and the sill pan

Here’s what matters as much as the window itself — how it’s set into the wall. In our rain, water will find the opening, and whether it drains back out or soaks into the framing comes down to the flashing and sill pan around the unit, not the glass. A great window gap-and-caulked into a crooked, unflashed opening will fail here; a modest one set square, insulated, and properly flashed will last. That’s why we don’t just swap glass — we look at the opening. Here’s how we handle window replacement, and when it’s genuinely a fix instead, here’s the repair-first approach. If you want to compare frame materials first, we walk through vinyl vs. fiberglass here, and you can see everything we do with windows.

Seeing any of these on your windows? Book a free assessment — we’ll tell you honestly whether it’s a repair or a replacement, and check the flashing while we’re there. See the window replacement service.

Questions homeowners actually ask

My windows fog up between the panes — can that be cleaned or fixed?

No. Fog or haze between the panes means the sealed insulated glass unit has failed and moisture is trapped inside where you can't reach it. Cleaning does nothing, and the insulating value is already gone. The glass unit needs replacing — though on many windows the sealed unit can be swapped without replacing the whole frame and trim.

Can a failed seal be repaired, or do I need a whole new window?

It depends on the frame. If the frame is sound and square, a foggy or failed insulated glass unit can often be replaced on its own for a fraction of a full window — that's a repair, not a replacement. When the frame itself is rotted, racked out of square, or the hardware is shot too, replacing the whole unit is the honest call. We'll tell you which yours is before you spend the big number.

Are drafts always a sign I need new windows?

Not always. A draft can be worn weatherstripping, a caulk joint that gave up, or a sash that no longer seals — all fixable long before the whole window is done. But a draft you feel from across the room on a single-pane or failed double-pane window usually means the unit itself is leaking heat, and that's a replacement conversation.

Do new windows really lower heating bills?

In this heating-dominated climate, replacing single-pane or failed double-pane windows with a good insulated glass package sealed into a tight opening does cut heat loss and makes rooms more comfortable. What we won't do is promise a specific dollar savings or payback year — that depends on your current windows, your home, your heating system, and utility rates, and anyone quoting a precise number is guessing.