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Can you name the 3 main causes of basement moisture?

There are over 9 million residential basements in Canada. Experts say between 30 and 50 per cent of these basements - 4 to 4.5 million of them - have moisture problems.


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October 8, 2015 by DMX Plastics Inc.

This is a Sponsored Post courtesy of DMX Plastics, Canadian manufacturers of the DMX 1-Step Underlayment system and the DMX AG Air Gap Membrane.

Studies show that between one-third to one-half of all Canadian residential basements (some 9 million structures) have moisture issues. That’s a market of 3 to 4.5-million homeowners with potential needs for basement moisture control.

But basement moisture problems – which can range from the health hazards of mould to major structural damage – usually come from three common sources. Here’s a really quick primer on where that moisture and mould is coming from.

Bulk Water is the most obvious cause of basement water ingress. “Bulk water” is a fancy term for water that you can see and measure. Basement bulk water drives from (a) Rain and snowmelt  (b) Plumbing leaks and (c) Groundwater (water table / sump pump problems). The first two of these are a plug-the-leak issue, time-consuming and finicky, but totally solvable. The third of these, water table issues, can be very serious and we will discuss them later in this series of articles.

Water Vapour – or high humidity – is the second most common cause of basement moisture problems. Warm, moist air in the house will form condensation on walls and floors, and especially behind joist space vapour barriers, and underneath laminate or on the underside of carpets. Many of these condensation issues can be solved by improving ventilation and/or air circulation and/or providing dehumidification.

Capillary Water or “Wick Water” occurs when water moves through porous materials like masonry concrete and stone. The water moves because there is a sort of suction effect from the tiny tube-like structures in these materials. Concrete slabs-on-grade are perfect materials to wick moisture into basements. Taping a 300 x 300 mm square of 3-mil poly to the concrete, and leaving it for 48 hours to see if moisture gathers, will tell you if your concrete is wicking water.