Black mould results from simple physics

Re: Tenants battle black mould, Aug. 17 I read with interest your story. I am a Peterborough landlord with two apartment buildings. Every winter I get at least two calls about mould on the walls.

After 20 years of this, I know what to expect when I get to the apartment in response to the mould call. I will be met at the door by a woman wearing shorts and a halter top or a man wearing a muscle shirt, even though outdoors it’s -20 C. The temperature in the apartment will be 26 or 27 degrees. The humidity will be so high that a sheet of paper hangs limp like a wet rag.

When I try to explain about humid air condensing on cool exterior walls and forming a breeding ground for mould, I am met with blank stares. As for wearing a sweater and leggins indoors – maybe Anne of Green Gables had to do that ....

Running exhaust fans to keep down humidity, keeping windows open strategically, avoiding long steamy showers, keeping the room temperature to a health 20 or 21 degrees and occasionally cleaning the walls all go a long way to control mould.

The walls in older buildings are often not insulated to a standard that can cope with the air tight envelope that modern vinyl windows and doors seals can achieve. Warm moist air meeting a cool exterior wall will result in condensation. That is simple physics that most of my tenants understand and accept. Ernest Dyck Cameron Street