Condensation on Windows and a Yearly Checkup

Row of new houses with finished exterior walls and windows.

On a humid week after a storm in Austin, every window in the house can fog or bead, and the running record window installation austin tx love my cc holds shows that most of those calls turn out to be condensation, not a leak. The skill is telling the two apart, because the fix for each is different.

Interior condensation

Front view of a brick building facade with sash windows and a wooden bench.

Moisture on the room side of the glass means indoor air is damp and the glass is cold. It shows after showers, cooking, or a night with the air conditioner running hard against humid weather. It wipes off. A double pane unit with a low e coating runs warmer than old single glass, so this is less common than it used to be, but it still appears on an aluminum window, which conducts cold, and in rooms with poor ventilation.

Fog between the panes

Contemporary A-frame house with large glass windows on a sunny day, surrounded by greenery.

Haze or droplets trapped between the glass layers of insulated glass cannot be wiped away. That means seal failure, where the edge spacer has let moist air in and the argon fill has leaked out. The unit stops insulating well and usually needs a new glass pack or a new window. It is not a leak into the wall, and it does not mean the opening was installed badly.

A true leak

A leak shows up outside the glass, at the sill, jamb corners or trim, and often only in rain. Look for water stains, peeling paint, bubbled drywall, a musty smell or a wet stool after a storm. Water on the wall below a window after rain at Zilker Park or along the Colorado River side of town points at flashing, sealant or weep holes, not at humidity.

The yearly walk around

Once a year, before spring storms, walk the outside with a flashlight. Check the sealant joints for cracks, open the weep holes with a soft pick, look at the sill for soft or darkened wood, and check the head for gaps where flashing should lap. Inside, run a hand along the stool and trim and look for stains, raised paint and swelling.

What to do with what you find

Small gaps in sealant can be recut and filled. A soft sill, or stains that keep returning, mean the wall needs to be opened and the cause traced. Window maintenance is mostly watching, and catching damp trim in Austin, TX early costs far less than replacing sheathing later. Keep a short note of what was checked and when, so a stain next year can be compared with this year.