What to do with Water and Mould?

What to do with Water and Mould?

Steve Weir July 10, 2017

With summer upon us, rain for many across the country, and cottage season in full-swing, Bryan addresses a few questions relating to mould issues in a cottage and leaky chimney flashing. 

Hi, Bryan. My cottage has a mould problem. It was built in 1955, 1,000 square feet with a crawl space approximately 10 inches from the ground to the bottom of the joists. The concrete block foundation has a single 6-by-8-inch vent on each side of the structure. If I extend my arm with a camera down through a vent I can see a white mould on the underside of the floor/joists. I understand that Amazon has a product, aerosol can type, that you can fumigate an area with, but will it do the job? - Al B., Brooklin, Ont.

Hi Al, and thanks! Based on the age of the cottage, and limited access into the crawl space, I’d be willing to bet my lunch money that it’s not insulated properly, and there’s no vapour barrier — which will cause condensation to build up on the underside of the subfloor. In my experience, there isn’t an aerosol product that would be an effective solution in this situation.

My suggestion would be to create a proper access into the crawl space so you can get someone in there to inspect the damage. Typically, anything more than about nine square feet of mould calls for a licensed environmental contractor to come in and clean it up safely and thoroughly. If the crawl space isn’t heated, the floor above should have an effective vapour barrier and at least R20 insulation. If the crawl space is heated, the exterior walls should be insulated to at least R20, and a continuous vapour barrier on the ground to prevent moisture from coming up from the soil.

Hi Bryan. The chimney on our two-storey, brick house has needed expensive repairs more than once, because of spalling and cracking of the bricks and consequently a little water leaking into the main floor family room ceiling below. In the last repair, the chimney was pretty much rebuilt and a cement cap put on. Recently, we noticed a little water leaking from the family room ceiling again. I checked the chimney and found more cracking and spalling just above where the outside perimeter of the roof meets the chimney. What should we do? -Allan B., Oshawa
Hi, Allan. It sounds like a flashing issue to me. If you’re planning to replace the wood-burning fireplace with a gas unit, you don’t really need a masonry chimney — you can likely direct the vent through an exterior wall. If you plan on removing the chimney altogether, I’d recommend getting an experienced contractor in to have a look at it. Besides, actually removing the masonry, you’ll need to repair and replace the section of the roof, soffit and fascia that it passes through. The only way to remove a chimney safely is brick by brick, with proper support and safety precautions, so be sure whoever you engage has experience to avoid any further issues or liability.

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