Weekly Maintenance for your Home

June – Week 26

Just like preventative maintenance on your car, if you take care of a few small items around the house every week, you can avoid many emergency breakdowns and expensive repairs.

Basement Humidity

High humidity in a basement can be a serious problem. It can rust tools, cause books to become musty and can grow serious quantities of mould that can affect your health. It is not good for office equipment and tends to make printers grab more than one sheet at a time. Once mould has begun to grow, it takes much less humidity to keep it growing. So why do houses get humid in the winter and basements get humid in the spring and summer?

Humidity itself is not a problem until it causes condensation, and that happens when humid air comes into contact with cold surfaces. In the winter, the cold surfaces are above ground. Because most basement have less air flow than the rest of the house, and are generally much cooler than the rest of the house in the summer because of the protective layer of soil around the basement, they tend to have both higher humidity, and more cold surfaces once the furnace is turned off.

The spring time is humid more because of excess moisture from the spring run-off than because of cold walls. Keeping the run-off water away from the house is the first step to keeping a healthy basement. But once we get into the summer, it is ordinary hot humid air that is depositing water on cold surfaces in the basement. The best defence is to fully insulate the basement and use a continuous vapour barrier to keep the moisture away from cold surfaces. Cold water pipes may need to be insulated as well to prevent sweating. Having no cold surfaces in the basement means that higher humidity will not cause condensation and will not cause mould.

Exhausting air from the floor of the basement to the outdoors certainly helps to control moisture, but this will rarely get the general level to below 60% RH. Resent research has begun to give credibility back to using de-humidifiers during the summer time in a basement as they can often get it down to 50% RH, and that is enough to stop a lot of problems in a less than perfectly insulated basement.

Don't forget to avoid stacking boxes tightly up against basement walls or directly on concrete floors. This creates a lack of air circulation and just helps to trap moisture against the cold surface. And boxes are organic, so they give the mould lots to eat.

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