Following the floods that wreaked havoc on so many Calgary homes, the damage is obvious. Streets lined with soggy drywall and waterlogged flooring are visible proof of how widespread the damage was.

But for some the damage was less apparent. On the edges of the floodwaters, the impact may have consisted nothing more than a damp carpet. However, despite appearances, residents should take care to ensure there are no potential dangers lurking out of sight.

“I just [inspected] a house a couple days ago and they had a little bit of water and they thought they had it all,” said Kevin Sixsmith, building inspector with AmericSpec Inspection Services. “I went in and I showed them a bunch more spots they needed to rip out. They thought they had it completely but they had low lying areas under the floor and in the basement, and it sucked up into the drywall.”

According to Sixsmith, who has already seen an upswing in demand for his services since the flooding, said hidden trouble spots such as underneath flooring and behind drywall can lead to big problems if not detected right away.

“Mould is the big problem. You get wet, you get mould. If you get wet carpet, it never really dries out properly. So you always run into problems if it’s not done properly and professionally,” he said.

Mould can cause serious long-term health risks for homeowners, such as respiratory disease and allergic reactions. People with mould allergies or compromised immune systems are most at risk of potential illness. Additionally, mould can also cause damage to building materials long after a flood.

Alberta Health Services advises cleaning all walls in a flooded house, even those that are on floors above the water line, since they will have been exposed to excessive humidity for long enough to start mould growth. This growth is often difficult to see without special instruments and techniques, so don’t assume surfaces are alright because they are one floor above the obvious problem zone.

When flooding backs water into the insides of walls and the cavities between ceilings and floors, hidden materials usually become waterlogged and contaminated with dirt or other organic materials. If these cavities are not opened, then cleaned and thoroughly dried, bacterial and mould contamination may become severe, leading to serious health problems for occupants.

One of the ways Sixsmith said homeowners can help ensure there are no hidden dangers developing in their home is with the use of moisture meters and a thermal camera. By scanning a surface with a thermal camera, the temperature difference created by the presence of moisture will appear differently than the surrounding area. Designed to measure the moisture content of various building materials, such as insulation, drywall, plaster, wood and fiberglass, moisture meters an be used to determine whether a material is moist enough to allow mould to grow. While influenced by other factors, mould will generally begin to accumulate on surfaces that contain approximately 20 per cent moisture.

“The big thing is going to be the hidden water underneath the flooring and in behind the drywall,” said Sixsmith. “If they’re carpets were wet and they didn’t do anything in behind the walls and the drywall, water is going to seep up in behind them and it won’t really dry out.”

For information on how to deal with mould in your home, visit the Alberta Health Services website at or contact a qualified home inspector in your area.