"Understanding Your Home" by Building Inspector Mark Visser
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Window condensation

Preventing window condensation
Excessive window condensation will lead to rotting window sash and/or frames. There are several ways to prevent or eliminate window condensation:
- Don't block hear registers
- Improve ventilation
- lower settings on furnace humidifier

If the humidity is too low it will cause skin irritations, static electricity when touching another person and loose furniture joints. If humidity levels are too high it will have a negative impact on all organic materials in your home and may even lead to mildew and mold.


Preventing Window Condensation
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Moisture condensation on windows is a common problem for homeowners. Condensation is caused by a number of factors, including the temperature of the window surface and surrounding air, and the relative humidity of the indoor air. Condensation can occur even on well sealed multiple glazed windows under extreme conditions - for example, when the outdoor temperature is unusual low or when the indoor humidity is very high.
Window condensation on older single glazed windows with storms is a common problem. It is caused by several factors, including the temperature of the window surface and surrounding air, and the relative humidity of the air.
Condensation on the exterior window pane or storm is a sure indication that warm moist house air is escaping past leaky interior panes. A good interior air-sealing job should solve this problem.
The best way of sealing the window unit is by adding on interior storm. Adding interior storms also will save big on energy costs.
The most common methods are:
- Rigid acrylic. It is magnetically sealed and fastened to the window frame.
- Flexible plastic, which is attached with double sided tape and heat shrunk into place.
Condensation on the interior window pane is a sign of high humidity levels. Window surfaces should be kept warm by good heat distribution and air circulation. Don't block heat registers with furniture, carpets or heat deflectors. Relative humidity levels can also be controlled by making sure that the humidifier on the furnace is adjusted to the outdoor temperature, see chard. For more information about humidifiers click here

The recommended settings may vary
from home to home.
It is important to change the settings
daily as suggested.

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