If you've ever woken up to foggy or wet windows, you've probably wondered whether it's a problem or just normal. The answer depends entirely on where the condensation is forming.
Condensation
on the Outside of the Glass This is a good sign. Exterior condensation forms when the glass surface is cooler than the outdoor dew point — typically on cool, humid mornings after a warm night. It means your windows are doing their job. It will evaporate on its own as the sun rises. No action needed.
Condensation
on the Inside of the Glass This is a humidity problem in your home, not a window problem. Interior condensation forms when warm, moist indoor air contacts a cool glass surface. Common causes in DFW homes include cooking without exhaust ventilation, long hot showers in poorly ventilated bathrooms, humidifiers set too high in winter, and new construction releasing moisture. Improve ventilation, run exhaust fans, or use a dehumidifier. The windows themselves are fine.
Condensation Between the Panes This
is a window failure. If you see fog, haze, or moisture trapped between the two panes of glass — and it doesn't wipe away — the hermetic seal has broken. Moisture has entered the insulated glass unit (IGU), and the argon gas fill has escaped. This cannot be fixed by cleaning; the glass unit must be replaced. In Texas, this is the most common type of window condensation because our extreme temperature swings put enormous stress on window seals year after year.
How to Tell the Difference Run
your finger across the glass. If the moisture wipes away, it's on the surface. If the glass is completely dry to the touch but still looks foggy, the moisture is between the panes.
What to Do About Failed Seals Contact Apex Windows at (214) 263-3008 for a free assessment. We replace only the glass unit — not the entire window frame — saving you up to 70% compared to full window replacement.
Serving the entire Dallas-Fort Worth metroplex — find foggy window repair near you or call (214) 263-3008 for a free estimate.
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About the Author
Alvin Paulson
Co-Owner & Lead Technician, Apex Windows & Glass
Alvin Paulson co-founded Apex Windows & Glass and brings over 30 years of hands-on expertise in foggy glass replacement, insulated glass unit (IGU) repair, and energy-efficient window upgrades. Born and raised in North Texas, Alvin has personally assessed and repaired thousands of windows across the Dallas-Fort Worth metroplex — from historic McKinney homes to new-build subdivisions in Frisco and Prosper. He is a licensed glazier and holds certifications in Low-E glass installation and argon gas window systems. Alvin's philosophy is simple: replace only what's broken, save the homeowner money, and back every job with a 10-Year IGU manufacturer warranty + Apex 1-Year workmanship warranty.