The short version

Season
Coldest weeks of winter, worst on still, frigid mornings
Where
Bedroom and bathroom windows, north walls, rooms with closed blinds
Cause
Indoor humidity condensing on the coldest surface in the room
Fix
Lower indoor moisture, warm the glass, and clean or replace damaged materials

Why the Front Range still gets wet windows

Colorado air is dry, so window condensation surprises people. But indoor air picks up moisture from showers, cooking, sleeping bodies, houseplants and humidifiers, and on a single-digit morning the inside surface of older glass and aluminum frames can be far below the dew point of that air. Water forms on the glass, runs down, and pools on the sill.

Many Wheat Ridge ranches still have original aluminum sliders or early replacement windows with metal spacers, both of which run cold. Heavy curtains and closed blinds trap moist air against the glass and keep it from being warmed by the room. Bedrooms with the door closed overnight are the classic spot.

Where to look for damage

  • Black spotting in the corners of the glass and on the frame gasket
  • Swollen, soft or gray wooden sills and stools
  • Peeling paint or dark streaks on the drywall below the window
  • Mold on the back of curtains or blinds
  • Stains on carpet along the wall under the window
  • Mold inside the window track on sliders

Matching the fix to what you find

  • IfOnly the glass and frame surfaces have small spotsClean them and reduce humidity. This is normally a small homeowner task.
  • IfThe wooden sill is soft or dark through the grainReplace the sill or trim piece and check the framing below.
  • IfDrywall below the window is stained or bubbledCheck the cavity with a meter. Condensation can run inside the wall, and exterior leaks can mimic it.
  • IfSeveral windows in the house are affectedMeasure indoor humidity and look at ventilation before replacing any windows.

Reducing condensation

  1. Measure

    A basic hygrometer shows whether winter humidity is unusually high. Colder outdoor temperatures call for lower indoor humidity.

  2. Vent moisture at the source

    Run bath fans during and after showers and use a range hood that vents outside when cooking.

  3. Let the glass warm

    Open blinds during the day, leave a gap at the bottom of curtains, and keep supply registers near windows open.

  4. Turn down humidifiers

    Whole-house or room humidifiers often run higher than needed in very cold weather.

  5. Upgrade when practical

    Windows with insulated frames and warm-edge spacers run warmer on the inside surface.

Common questions

Is condensation between panes of glass a mold risk?
Fogging between panes means the seal has failed. It affects clarity and insulation but is not usually a mold source inside the room.
Can I clean window mold myself?
Small areas on glass and frames can be cleaned with detergent and water while wearing gloves and an N95. Larger areas or damaged drywall are better assessed first.

General information for Wheat Ridge, not a quote or professional advice. In an emergency, call 911.