Moisture problems in the winter on my windows.

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waynefishburn
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Joined: Thu May 29, 2008 1:58 pm

Moisture problems in the winter on my windows.

#1 Post by waynefishburn »

My question is why do I get moisture on the inside of my windows during the cold months? I do heat my ranch home with a wood burner and my windows are single pane, wood structure from 1986.

Thanks for your help,
Wayne

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Windows on Washington
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Joined: Fri Oct 27, 2006 11:23 am
Location: DC Metropolitan Area-Maryland/Virginia/DC

Re: Moisture problems in the winter on my windows.

#2 Post by Windows on Washington »

Air can hold varying amounts of water vapor or moisture. The warmer the air is, the more moisture it can hold. The amount of moisture in the air, expressed as a percentage of the maximum amount the air could hold at a given temperature, is called its relative humidity. For health and comfort, indoor air should contain some moisture. The relative humidity should generally be between 30% and 40% at normal room temperature.

The relative humidity of air can be increased by adding more moisture or by reducing the temperature. When the relative humidity reaches 100%, the air can hold no more moisture, and water begins to condense from it. The temperature at which this condensation occurs is called the dew point temperature of the air. When moist air comes in contact with a cold surface in a home, it may be cooled to its dew point temperature, resulting in condensation on the surface.

Single-glazed windows characteristically suffer from water condensation problems and the formation of frost on the inside surface of the glass in winter.

Windows don’t cause condensation, but historically they have been the first and most obvious place it occurs. This is because windows generally have lower thermal resistances than insulated walls, ceilings, and floors. As a result, their inside temperatures are usually lower than those of other surfaces in a home during cold weather. If the air in a home is humid enough, water will condense from it when it is cooled at a window surface.

Condensation is most often thought of as a cold climate winter problem. However, in hot, humid weather, moisture can condense on the outside surface of a poorly insulated window in an air-conditioned building.

Left unchecked, condensation can damage window frames, sills, and interior shades. Water can deteriorate the surrounding paint, wallpaper, plasterboard, and furnishings. In severe cases, it can seep into adjoining walls, causing damage to the insulation and framing.

The indoor air coming in contact with energy-efficient windows is less likely to be cooled to its dew point temperature because the inside surface temperatures remain higher during cold weather than do those of windows with single glazing, traditional metal spacers, and metal frames.

Condensation is even more likely to occur at window spacers and frames, which are usually less insulating than the corresponding glazings. With so many insulating glazing types available, efforts to prevent condensation have shifted toward the development of better insulating spacers and frames.

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