Window Frequently Asked Questions
Is condensation or fog on my windows bad?
Foggy windows or windows with condensation on them are signs to reduce indoor humidity before it causes hidden, costly problems elsewhere in your home, such as peeling paint, rotting wood, buckling floors, insulation deterioration, mildew, even moisture spots on ceilings and walls.
Do windows cause condensation?
Windows do not cause condensation. However, windows are often the first places where condensation can be seen. You’re probably not surprised when your bathroom mirror becomes fogged during a hot shower or bath. And you’re probably not surprised when your car or truck windows fog up in humid weather or when you have several passengers in your vehicle during the winter. Your bathroom mirror and vehicle windows don’t cause the condensation, and neither do your home’s windows. Again, these are just the first places you actually see condensation.
What causes condensation?
Condensation forms when warm, humid air contacts a cold surface. Moisture is in the air all around us. Warmer air can hold more moisture. As air cools, it contracts and its moisture condenses. When the temperature drops, the first place you will see any condensation is on the windows. Your windows are the coldest surfaces indoors. During colder months, indoor air is much warmer and holds more moisture than outdoor air, which is colder and dry. Warm, humid indoor air cools and contracts as it contacts the cooler windows, and the moisture condenses on the glass.
Why is indoor air so humid?
Indoor humidity is caused by everyday living. Showers, baths, cooking, washing dishes, doing laundry, and cleaning all add moisture to the air in your home — as much as four gallons or more per day in some homes. Additionally, we exhale moisture into the air as we breathe. Today’s energy-efficient, well-insulated homes tend to keep down heating and cooling costs. But the same things that block outdoor air from entering our homes also keep moisture from venting to the outdoors.
Can humidity cause health problems?
It was once believed that winter use of humidifiers helped people stay healthy, but studies have shown this to be untrue, particularly for healthy people. In fact, humidifiers can actually create health problems. While manufactures maintain that humidifiers can benefit plants and furniture, the Association of Appliance Manufacturers states that no evidence exists to associate humidifier use with any medical benefits.
What kind of health problems can humidity cause?
Mold and mildew thrive in moist areas with plenty of organic material, such as wood, plaster, and some types of insulation. Many types of mold easily become airborne, which is often their means of reproduction. When inhaled or ingested, molds are known to cause local or systemic allergic reactions, sinus and nasal irritations and infections, chronic respiratory problems, dizziness, lethargy, and can trigger attacks in people with asthma.
What kind of structural damage can humidity cause?
Nature, as usual, will find a way to maintain balance. Because humid indoor air tends to be under higher pressure than outdoor air, indoor air constantly pushes its way outward to the area of lower pressure — right through wood, plaster, insulation, and concrete. This process can cause insulation to deteriorate; paint to blister and peel; unsightly stains on walls and ceilings; and rotting of floors, wall supports, and other structural supports, including foundation damage.
I have condensation on my double-glazed windows. How can I tell if it’s from bad seals or indoor humidity?
Before calling for service, try this easy test. Run your finger through the area where the condensation has formed. If your finger gets wet and leaves a trail through the condensation, the condensation is on the room side of the glass. This tells you that condensation has appeared because of excessive indoor humidity and is not due to a faulty seal.
What is a seal failure?
Whenever you have water spots or dirt in between your glass panes and not on the panes’ surface, you have a failed seal. The easiest way to tell is if you cannot clean off the spots from the inside or outside. A seal failure occurs when the glass has pulled away from its spacer, or the adhesive has loosened. All that is needed for a seal failure to occur is a gap the size of pinhole. Then air and moisture can get into the chamber between the two panes of glass.
What do I do if I have a seal failure?
If you have a seal failure, please give us a call. If it is a window installed by Mr. Window Inc., we can usually order a new sash or glass pack for you by phone. You can change the sash yourself or have Mr. Window do it for a service charge or without charge if you are within the coverage terms of our free service agreement (which is two years for customers who fill out a customer service questionnaire upon completion of the Mr. Window product installation; one year otherwise).
My old windows did not have condensation problems. Why do my new windows?
If your old windows were drafty, those cracks allowed excess moisture to escape outdoors, when the wind wasn’t blowing in. Your new windows are better insulated, so indoor humidity can’t escape. Windows do not cause condensation, nor can they eliminate condensation. Your new windows are alerting you to excess humidity in your home.
How can I reduce indoor humidity?
There are a number of measures for increasing ventilation and controlling indoor moisture to help eliminate indoor humidity. You can increase ventilation by:
- Opening a window in each room for just a few minutes, letting stale, humid air escape and fresh, dry air in. Your heat loss will be minimal. Please note that this is a temporary solution if you have an acute problem.
- Venting all gas burners, clothes dryers, etc., to the outdoors.
- Installing kitchen and bathroom exhaust fans to draw steam outdoors.
- Keeping attic vents open and clear.
- Installing storm windows to keep interior glass warmer.
You can control indoor moisture by:
- Setting your humidifier at the level recommended below for winter temperatures.
|Outside Temperature||Inside Relative Humidity|
|-20°F||15 — 20%|
|-10°F||15 — 20%|
|0°F||20 — 25%|
|+10°F||25 — 30%|
|+20°F||30 — 35%|
- Checking indoor humidity with a humidity monitor or regulating indoor humidity with a humidistat, available at most building supply stores or home centers.
- Grouping indoor plants in one sunny room and avoid watering excessively.
- Waterproofing basement floors and walls. Run a dehumidifier if needed.
- Insulating under the seat and head of bay and bow windows where condensation forms to keep window glass warmer. Run an electric fan near the window to increase air circulation.
I lifted my double-hung sash out of the frame to clean it. Now that I put it back in, it does not work properly. What should I do?
The homeowner can usually resolve this problem quite easily. First, if the sash was tilted in, while all the way down, the pins have come out of the “shoe.” If you take the sash out, you will notice two metal pivot pins sticking out of it. If you then look at the sides of the window frame where the sash came from, you will notice a plastic shoe on either side of the window. The pins from the sash must slip into these shoes, so you will have to use a flathead screwdriver or pry bar to move the shoes up past the sill so that the pins will slide into them. Now close your window and test to see if it is functioning correctly by moving it up and down. You’ve solved the problem!
If you lifted the sash out while the sash was raised past the sill, take the sash out and look at the shoes in the frame. Make sure both are level and that you are putting in the sash above them. This is so the metal pivot pins will slide into the shoes that guide and hold the window. Failure to do this may cause the sash to be hard to open or close, or the sash may come crashing down.