Condensation
Introduction
This information will review some of the causes of condensation and some helpful hints to relieve
the situation. Please keep in mind that the window or door is not the cause of the problem. The
cause is humidity.
Condensation is actually the result of high humidity levels in your home. It generally appears as
moisture or ice on the interior lite of glass. The problem is more visible on the glass of your
windows because the surface condenses more easily. This means that the glass has the lowest temperature
of any visibile surface in your home.
It needs to be noted that if moisture is visible here, it could be happening elsewhere as well.
Problems such as peeling paint, rotting wood, mildew and moisture spots are typical symptoms of condensation.
We have complied some helpful hints and possible solutions for your condensation problems. Please use your judgement
as to which solutions may apply to your home. Keep in mind that the windows are not the cause of condensation, they are simply
an indicator of a larger problem.
Humidity
Humidity is the amount of moisture in the air. It may come from various sources. Your home needs
a certain amount of moisture, but deciding how much you need is a critical decision.
The chart to the right will help you with the moisture level of your home; reducing humidity while maintaining comfort.
The chart is based on the inside relative humidity of a 70 degree indoor temperature.
Moisture
As stated before, moisture may come from a variety of sources. We have complied various activities and how
much moisture a family of four contributes to their living environment.
Average daily living activities can contribute more than 18 gallons of water per week for an
average 
family of four. As you can see, normal activities that you take for granted can greatly
contribute to the humidity levels in your home.
Condensation
Condensation is the fog that is evident on the glass of your windows. This is the same fog that
appears on the outside of a cold glass during the summer.
It's Cause
The cause of the condensation is extreme moisture in the air. When warm air meets a cooler surface, it condenses.
This creates the visible moisture you see on the surface of your windows. Condensation also occurs when
the flow of warm air is restricted from reaching window surfaces.
Too Much Humidity
If there is moisture on your windows, it is important to check your entire home.
Problem areas could reveal themselves as damp spots on ceilings and walls. The end result
could be the moisture passing through the walls, insulation, and to the exterior walls causing
peeling or blistering paint. This could eventually cause rotting of the frame of the house if left untreated.
Location and Time
Some regions are more prevalent to condensation than others. Generally areas that reach 35 degrees
Fahrenheit or below in the winter months are more suseptible to condensation.
Interior condensation is more likely in the winter months. This happens when moisture in the air
contacts a surface whose temperature is lower than the dew point (the temperature in which air manufactures dew).
Exterior surface condensation usually occurs on sultry, humid summer days. An example would be that
moisture forms on the outside of a window in the summer when an air conditioner is being used in the
home. This creates a surface temperature on the glass below the dew point.
New Home vs. Old Home
You tend to see less condensation in older homes. Years ago people were not so concerned about humidity levels
or energy efficiency in a home.
Newer homes are manufactured more air-tight. This leaves the moisture trapped or locked in the
home. This means that newer homes leave no outlet for the humidity to escape unless steps have been
taken to vent the moisture during construction.
Measuring Humidity
Although there are scientific measures to determine the humidity levels in your home, most homeowners do
not have access to such means.
An easier way for the average person to monitor humidity is to watch for the obvious signs in your residence.
When you see the start of condensation on your windows, this is a sure sign that your humidity is reaching
a level that could be too high.
Remember that watching the humidity level on the news has no bearing on the levels in your home.
This is a humidity reading for the humidity in the air outside.
Reducing Humidity
There are some steps that you, as a homeowner, can take to reduce your indoor humidity level.
One way is to make sure that all appliances requiring a vent are vented properly. This includes
items such as clothes dryers, gas heaters and exhaust fans. Exhaust fans are an excellent way to
increase the air flow and reduce humidity if installed correctly. Areas that would benefit most
would be bathrooms and kitchens.
Another option is to make sure that your home is properly vented. There are a couple of ways to
achieve this effect. One solution for more severe cases would be to open a window in each room for
a short period of time. This is a very temporary solution.
A more permanent solution would be to make sure that all areas such as attics and crawl spaces
have been vented. Many people cover attic vents or louvers for the winter thinking that they are
keeping the cold air out, not realizing that they are also keeping in moisture. For more specifics
on these and other ideas, we recommend a heating and ventilation contractor or other specialists.
Types of Windows
Some types of windows are more likely to condensate such as bow or bay type window units. These
windows are more exposed to the environment, and therefore, may be somewhat cooler in temperature.
Another consideration is the lack of air movement within a bow or bay unit. Due to the shape of the
unit, the air-flow is somewhat restricted. One solution to this problem is to make sure that the unit
is properly insulated upon installation. Contact your contractor or insulation specialist for further
details.
The other solution is promoting air circulation by the use of a fan. This will keep the air circulating
in the unit and the room.
Coverings
Another concern might be the type of window coverings that are being used. Remember, just as the windows are
not the cause of condensation, neither are the curtains nor the blinds. They are merely another contributing
factor to a condensation problem. Again, restricting the air-flow to your windows can contribute
to a possible condensation problem. The condensation is more likely to occur when window coverings are too close
to the windows, restricting the flow of warmer air.
Temporary
Your condensation problem may be only a temporary situation. Below, we have outlined three examples
of this.
The first is when a new home is built. A great deal of moisture is released from the building materials
such as wood or plaster. During the winter months, the moisture will be released into your home. This
circumstance usually occurs only during the initial heating season.
The second is during the initial heating months of the winter. This is simply humidity stored in
your home. This symptom should gradually dissipate during the season.
The third is a severe, rapid change in the temperature over a short period of time during the winter.
New Construction
When planning your new home, here are some helpful suggestions that should be considered:
1) Choose a wood window instead of a metal unit. Metal is a much poorer insulator than a wood
product.
2) Make sure that all attics or concealed spaces are properly ventilated.
3) Make sure that all appliances (such as dryers or exhaust fans) are properly ducted, sealed and
vented to the exterior of the home. Gas appliances should be a major concern. Water vapor is one
of the by-products of gas combustion.
4) Make sure that your contractor considers the most appropriate way to keep soil moisture from
permeating the basement or foundation.
5) Proper insulation, goes without saying, is one of the most valuable tools in any energy
efficient residence. But many people often forget their water pipes and cold air ducts. Any pipes
(such as cold water pipes) or ducts that condensates in the warmer months of the year, should be
covered. This should be done with an insulation that has an exterior vapor barrier.
Summary
We hope that this information is helpful in your quest for the answers to you condensation
questions.
This information is a general overview of the condensation problem and may not apply to every
person or situation. The main thing to remember is that condensation is caused by high humidity levels in
your home not bad windows.