Moisture Building Up?

October 24, 2006

It never fails, folks. Every Fall I start getting calls about condensation on windows, mold on the walls in the bedrooms, stains behind bedroom dressers, stains on ceilings and it goes on and on. Some homeowners stress the fact that they have just put in new windows; so why the moisture? Well let it be known you have tightened your home up a few notches so lets go back a few steps.

1. What have you done all summer long to vent you home i.e.: Basement or Crawl Space?

2. What improvements have you made to your home windows, doors, ventilation, siding, roofing, insulation etc.

3. What have you done to compensate for these changes in exhaust ventilation, heat recovery ventilation, continual flow furnace motors ? Oops! None of these? Not even crawlspace or basement ventilation ?

The moisture you are now fighting with in most cases has been with you all summer, locked in the basement or crawlspace waiting for you to start up the heating system. Incidentally, this holds true for those of you who have radiant heat as well. Now, you’re heating air containing moisture, expanding it many times, and now it is looking for a way out of your home. So vent the crawlspace or basement with a Humidex System or use a bathroom fan controlled by a dehumidistat or open a window with your summer furnace blower activated or even use your range hood fan in the kitchen.

When you see signs of moisture you must start venting to reduce the relative humidity to a level below dew point. Purchase a humidity indicator to control moisture levels.

There should be a guide on the dehumidistat for the recommended inside humidity setting that is acceptable for the outside air temperature.

Summer Temperatures = 50% Humidity Setting

0 to -12C = 40% humidity setting
-12 to -18C = 35%
-19 to -25C = 25%
-25 to -30C = 20%
-31 or below = 15%


For information on this call Resources Canada 1-800-387-2000 and order the book Consumers Guide to "Keeping the Heat In." It’s Free!! It’s Just That Easy Folks.

Following is a link to their website and I encourage you to visit it to learn ways that you can make your home more energy efficient, healthy and comfortable. www.oee.nrcan.gc.ca