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 following chart will help you with the moisture level of
your home; reducing humidity while maintaining comfort. The chart is based on the inside
relative humidity for a 70° indoor temperature.
As stated before, moisture may come from a variety of sources. We have compiled various
activities and how much moisture a family of four contributes to their living environment.
· Normal Breathing
---1/2 pints per hour
· Cooking (3
meals a day) --- 4 to 5 pints per day
· Showering ---
1/2 pint each
· Plants --- 1
pint per day/per plant
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.
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
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 & Time
Some regions are more prevalent to condensation than others. Generally areas that reach
35° Fahrenheit or below in the winter months are more susceptible 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 of the glass
below the dew point.
New Home vs. Old Home
You tend to see less condensation in older homes. People were not so concerned about
humidity levels or energy efficiency of a home years ago.
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.
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.
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 profit 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 desired 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 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 moving.
Another concern might be the type of window coverings that are being used. Remember that
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 tight to
the windows- constricting the flow of warmer air.
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
discharged in to your home. This circumstance usually occurs only during the initial
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
Just as the windows did not create the condensation, there is little you can do to the
windows to stop the problem. Like stated above, it could be a sign of a much larger
problem. Remember- the glass in your windows is just an indicator.
However, adding a good storm sash that provides an escape for moisture or changing the
glass to a double paned unit will increase the temperature of the inside lite of glass,
therefore decreasing the chance of condensation. Do not forget that other parts of the
home may also have the same problem, just not as visible or obvious.
When planning your new home, here are some helpful suggestions that should be considered;
· Choose a wood window
instead of a metal unit. Metal is a much poorer insulator than a wood product.
· Make sure
that all attics or concealed spaces are properly ventilated.
· 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.
· Make sure
that your contractor has considered the most appropriate way to keep soil moisture from
permeating the basement or foundation.
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
We hope that this has been helpful in your quest for the answers to your condensation
If you have tried the suggestions listed on the previous pages such as proper ventilation
and reduction of humidity levels in your home and have been unsuccessful, contact a
professional heating contractor about other humidity reducing ideas.
This 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 high humidity levels in
your home- not bad windows.
thanks to Lincoln Windows and Artec Interiors for their help with this issue.
Check out their websites for more information.