What condensation is actually telling you
Condensation forms when warm, moist air contacts a cold surface. When it appears on the interior surface of your windows, it means the air inside your home is too humid for the temperature conditions. The windows are just the messenger — they're the coldest surface in the room, so that's where you see it first.
Condensation between panes is a different issue: it means the sealed unit has failed and the inert gas has escaped. That is a window problem, and replacement or resealing is the right call. But if the moisture is on the interior glass surface, the window is likely fine.
Replacing windows to fix interior condensation is like replacing the thermometer to fix a fever. The real issue is excess indoor humidity — from cooking, bathing, occupants, or inadequate ventilation — and the fix is usually mechanical: better exhaust ventilation, an HRV, or a dehumidifier.
What actually causes high indoor humidity?
Newer, tighter homes trap moisture that older, leaky homes used to exhaust through gaps. If your home has been recently air-sealed, insulated, or had new windows installed without adding mechanical ventilation, humidity will rise. BC building code requires heat recovery ventilators (HRVs) in new construction for exactly this reason.
Lifestyle matters too. Cooking, showers, plants, and even breathing all add moisture to the air. A family of four generates roughly 10–15 litres of moisture per day through normal activity. If that moisture has nowhere to go, it shows up on your windows.
How to tell which problem you actually have
A Home Performance Report will model your home's air tightness, ventilation rates, and likely moisture loads. If the condensation is a ventilation problem, the fix might be as simple as running your bathroom fans longer, or adding an HRV — far less expensive than replacing windows that don't need replacing.
Not sure whether your condensation points to a window problem or a ventilation issue? A Home Performance Report will give you a clear answer before you spend anything.
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