Every November the calls start: “My windows are dripping wet every morning — is something wrong?” Sometimes yes, sometimes no. Window condensation is your home’s way of telling you something; the trick is knowing how to read it.

Condensation on the Inside Surface

Water beading on the room-side glass means indoor humidity is meeting a cold surface — the same reason a cold drink sweats in July. Common in winter when we cook, shower, and run humidifiers with the house sealed tight. Light morning fog that burns off is usually a humidity-management issue, not a window issue: run bath fans longer, crack the kitchen fan when cooking, and keep indoor humidity around 30–40% in cold weather.

But persistent pooling water on sills leads to mold, ruined paint, and rotted wood. If towels on the sill are part of your winter routine, the glass surface is staying too cold — a hallmark of single-pane windows and old aluminum frames that conduct cold straight through.

Condensation Between the Panes

Fog or moisture trapped between the layers of a double-pane window is different: the sealed unit has failed. The insulating gas is gone, moisture has taken its place, and no amount of wiping will ever reach it. The window’s insulating value is largely lost. The good news: in many cases we can replace just the glass unit rather than the entire window.

Condensation on the Outside

Dew on the exterior glass on cool mornings is actually a compliment — it means your window is insulating so well that the outer pane stays cold. No action needed.

The Rule of Thumb

• Inside surface, occasional: manage humidity.
• Inside surface, daily puddles: your windows are too cold — upgrade candidates.
• Between panes: failed seal — call us for a glass unit replacement quote.
• Outside surface: relax, that is a good window.

Ready for honest answers about your windows, doors, or glass? Schedule a free in-home estimate with our award-winning team. Call us in the Tri-Cities at (509) 586-1177, in Walla Walla at (509) 529-5110, or request your free estimate online.