Condensation

• About Condensation
• Measuring a Home’s Humidity Level
• Excess Moisture: Causes and Cures
• Condensation – Information from the Better Business Bureau

About Condensation

During cold winters, there is a great temperature difference between the inside of a house and the weather outside. When the temperature drops outdoors, the glass on your windows and doors tends to have lower temperatures than other surfaces in your house, and is the first place that you’ll notice condensation in your home. This is not due to any defect in your window or door; it’s simply a sign of high humidity in your home.

Warmer air is capable of holding much more moisture than cooler air. The temperature for vapor filled air goes down when it gets close to cooler surfaces, and so does its ability to hold moisture. When the temperature reaches its dew point, the moisture condenses, attaching to the nearest cool surface. The first surfaces where you’ll notice this happening is the glass on windows and doors.

Condensation is an unsightly problem. The last thing you want on your windows is a fog blocking the view. But the problem goes deeper than that—if condensation is a chronic occurrence in your home; chances are that you have excessive humidity. If water is accumulating on glass, chances are it is accumulating on other harder to see surfaces such as wall and roof cavities. If left uncontrolled, excess moisture can have serious consequences, including:

• Mold or mildew

• Wood rot and warping

• Roof ice build-up

• Damp, ineffective insulation

• Discolored, blistered or bubbling paint

• Damaging moisture inside walls and attic

Excessive humidity is more likely to occur in newer or recently remodeled homes with tight, energy efficient construction, causing a build up of moisture to the interior. There are ways you can reduce humidity in your home. Please consult Measuring a Homes Humidity Level and Excess Moisture: Causes and Cures for tips on identifying and eliminating sources of excess moisture in your home.

Measuring a Home’s Humidity Level

You can determine how much moisture is in your home with an inexpensive Hygrometer that can be purchased from your local hardware store.

Place the Hygrometer in your home for a few days and record the readings each day. Compare your data to the chart below.

As outside temperatures drop, the indoor relative humidity level of your home should decrease. For homes with windows equipped with insulating glass, the University of Minnesota Agriculture Extension Service reports that the following humidity levels can be maintained in the home without causing window condensation.

If your home’s relative humidity is higher than this chart, please consult Excess Moisture: Causes and Cures for tips on identifying and eliminating sources of excess moisture in your home.

If you are experiencing condensation on your Marvin windows or doors, and your relative humidity is within the ranges shown on the table above, please contact a Marvin retailer near you and request that a service representative visit your home to assess the problem. Please keep your recorded humidity data handy, as this is important information needed by the service representative.

Excess Moisture: Causes and Cures

Cause: Inefficient windows with extremely cold glass surfaces

Cure: Install energy-efficient windows and doors. High-performance windows, such as those made with Low E II coatings with Argon gas, make the most of the sun’s heating rays during cold months and maintain a remarkable temperature difference between the indoor and outdoor panes of glass.

Cause: Inadequate ventilation of windows

Cure: Keep window coverings open during the day to allow air circulation and make sure patio doors have heat vents beneath them.

Cause: Moist air trapped in attic

Cure: Seal around indoor light fixtures to prevent warm, moist air from rising to the attic. Install soffit vents to prevent attic rot, making sure to keep vents clear of dirt and garden debris.

Cause: Radiator or kerosene heat

Cure: Use dryer sources of heat such as gas or electric furnaces.

Cause: Cooking and dishwashing

Cure: Vent stove range hoods and dishwashers to the outside. Cover pots while cooking.

Cause: Stale, damp air

Cure: Install an air-to-air heat exchanger to vent moist air outside. Some air quality systems recover up to 97% of the existing warmth and energy to heat incoming fresh air.

Cause: Showers and baths

Cure: Make sure bathroom exhaust fans are vented to the outside and use fans regularly.

Cause: Ironing, washing and drying laundry

Cure: Make sure the clothes dryer is vented to the outside and/or install an exhaust fan in the laundry room.

Cause: Dirt floor crawl spaces

Cure: Vent crawl space and/or cover dirt with plastic to create a vapor barrier that will prevent moisture in the soil from rising into the home.

Cause: Groundwater seeping through foundation

Cure: Install gutters, flashing and downspouts and grade dirt to channel water away from the home’s foundation. (Minimum 6" slope over a 5' run.)

Cause: Indoor plants

Cure: Use small fans to circulate air.

Cause: Excessive humidifier use

Cure: Keep indoor air quality to optimum humidity levels. Hygrometers are available at most hardware stores, and can be used to measure home humidity levels.

Cause: Damp basement allows ground moisture into home

Cure: Running a dehumidifier in the basement can reduce musty odors and mold.

Cause: Unseasoned firewood

Cure: Minimize indoor firewood storage.

Cause: New wood, plaster, cement, and other building materials

Cure: Building materials contain a great deal of moisture. As soon as the heat in the home is turned on, this moisture will flow into the air and settle on windows and other cool surfaces. Plan for extra ventilation for the first few years in a new home or newly remodeled home.

Condensation – Information from the Better Business Bureau

Condensation is visible evidence of excessive moisture in the air. It may appear as water, frost, or ice on the room surface of windows and doors. The warmer the air, the more water the air can hold, which means that the air in the center of any given room will hold more water than the air adjacent to the window or door walls, since this area is always cooler. When the warm, moisture laden air moves toward the cooler window or door wall it becomes cooler and cannot hold the moisture it held when it was warmer. Therefore, the moisture is dropped and appears as water on the glass and frames of windows and doors. This occurs more frequently during the winter months because of the extreme difference during the winter months, when the average outdoor temperature drops to 35 degrees or less. It would be wise to maintain a 25 to 30 degree relative indoor humidity.

Ventilation is a very effective way to remove excessive moisture from the air, which is why old, poorly insulated houses with single glazed windows, often times do not have condensation problems. This is because the air is changed by infiltration around the windows, doors, vents and other openings. Newer homes, which are constructed to meet current insulation standards and energy conservation requirements, or older homes, which have been newly insulated through the addition of attic and basement insulation, and installation of primed windows with dual or triple glazed glass, are now so air-tight that they present a new problem.

Condensation may be the result of one of three occurrences:

• New Construction or Remodeling -- Building materials contain a great deal of moisture. As soon as the heat is turned on, this moisture will flow out into the air and settle on windows, etc. This will usually disappear following the first heating season.

• Humid Summers -- During humid summers, houses absorb moisture. This will be apparent during the first few weeks of heating. Then the house should dry out.

• Temperature Change -- Sharp, quick and sudden drops in temperature, especially during the heating season, will create temporary condensation problems.

If you have an existing moisture or condensation problem, do not count on correcting it merely by installing new windows. An insulated window should help relieve the situation. You must remember - windows do not cause condensation. Therefore, windows cannot cure condensation.