Acme FAQ’s

To Measure Width:  With the window open, measure the distance between the left jamb and right jamb. Inside the track where the window sash slides up and down.

To Measure Height: With the window open measure from the lowest point of the bottom of your window sill to the top of the window opening (header) inside the top of the frame.

When an interior window leaks warm moist air, moisture condenses on the tighter end of the window sill on the cooler storm.

“Steam” (Condensation) occurs when invisible water vapor in the air condenses on the cool glass. Windows and metal window frames tend to be the coolest surfaces in our homes so moisture forms there first – just like condensation beads up on the outside of your ice-cold lemonade glass in the summertime.

Condensation requires a cool surface and moisture in the air. This moisture is measured as a percent of the total amount that the air will hold at a specific temperature, and the percentage is known as relative humidity. Warmer air holds more moisture and cooler air holds less moisture.

Windows fog up in the early morning because lower overnight temperatures cool the glass below the dew point. When the outside temperature rises later on the day, the glass warms and condensation disappears as visible moisture evaporates into invisible air vapor.

This normally occurs on the inside of the storm windows. Prevailing wind creates pressure on the side of your home facing the wind and creates a negative pressure on the downwind side. (The same principle causes high and low pressure around an airplane wing and creating lift).

If windows are not a perfect fit, it can leak some air. Windows facing the wind tend to allow cold, dry exterior air to leak in. This keeps these storm windows dry.

On the downwind side, warm and moist interior air tends to leak from the inside window and can be trapped by the cold storm. The moist air condenses on inside of the storm. (This is the window you want to keep slightly open to ventilate your home because the air will always push out without a draft.)

All storm windows should have “weep holes” at the lowest point of the window frames to allow condensation to drain from between the windows. These small weep holes can also ventilate the space and reduce condensation. Sealing the interior window will help eliminate condensation on the storm windows.

For some lucky homeowners, window condensation is just a temporary annoyance. A few weeks after the heating season begins, interior air dries and condensation stops forming on windows.

In other homes, though condensation continues, becoming a  serious problem. Water runs off the windows and damages wood surfaces. Ice may form on windows and frames. Storm windows remained fogged up and icy all winter as water ponds between the frames. This serious condition needs to be addressed before it rots wood, supports mildew grown, and damages the home structures.