mould growing around ducts in attic

Here at Nusite Group Contractors, we get dozens of calls every month in Toronto and the surrounding GTA for mould removal in the attic.  The homeowner usually notices a leak or musty smell in the attic and discovers, to their horror, an entire eco-system of mould that has been growing and spreading throughout their attic.  There are several reasons you may have mould growing in your attic, here are a few reasons it may be growing in yours.

What’s Mould Doing in the Attic?

Mould is a fungus that populates our basements, homes and attics by releasing spores into the air. Because it’s a living creature like all other animals and plants, it can’t survive for long without moisture. When you discover black mold in your attic it’s a sure sign that dampness is coming in from somewhere. But why is this happening? When you have the answer to that question, you’re halfway through getting rid of that nasty mould.

attic leak in Toronto attic

The Biggest Single Cause

The number one reason for your problem is inadequate roof space ventilation. By this, we mean the space above your ceiling beneath the roof itself. This causes moist air to accumulate in motionless air pockets. When this happens, the humidity condenses, and falls like light rain onto the ceiling below.

There are a variety of different ways to improve air circulation in roof space, ranging from passive roof vents to extraction fans. Installing these is hardly a job for an amateur. At best you may not solve the problem. At worst, you could cause a severe leak. Consider finding a roofing expert to help you solve the problem instead.

How Moisture Enters Attics

If the moisture’s entering from outside, you’ll know about it soon enough when you start noticing ceiling stains. It’s far more likely to be filtering up from the rooms below. Moist hot air rises and ceilings are seldom airtight. All you need is the dishwasher, washing machine or dryer running while the central heating’s on, and nature will do the rest.

To fix the problem you need to do two things. Sit in the attic at night with all the lights switched on below, and look for chinks of light. These will mostly be around the lights, unless some coving has worked loose too. When you’ve identified the problem area, you can seal it off with paintable caulking from below.

mould growing around ducts in attic

More Tips

If closing any gaps does not solve the problem, then your ceiling material is permeable and letting moisture through. This can be solved with attic floor insulation acting as a moisture barrier. Just make sure you don’t leave the slightest gap, or your efforts may be for nothing.

Because mould loves warmth as well as damp, an inadequately insulated hot water heater can encourage mould to take hold too (especially if ceiling is not properly insulated either). When walking around and investigating areas like this, be sure to take a face mask with you, and watch your step.

Practical Limitations

Over and above the danger of inhaling mold spores and setting of chronic bronchial infections or even an asthma attack, being in an attic is potentially dangerous because it’s a long way down if you trip and fall. Moisture-proofing roof space is also quite a complex task, because you have to get into inaccessible corners.

It can take a deal of time to establish the root causes of your problem. While some smaller problems can be fixed yourself, be aware that if you do see mould, it is likely growing in other areas also. If you have a busy schedule and there are other things that you’d prefer to do, it could make more sense to find a certified mould removal specialist to do the job.  Have questions?  Contact us here!

mould in Toronto attic


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Waterproofing & Foundation Specialists at Nusite Contractors Ltd
As a family-owned waterproofing and foundation repair business with over 30 years of experience in Toronto, we are proud of our work and stand by it with a full warranty. We’re a service company, working for you. We make sure our customers understand the entire building and repair process, and ensure that our work is done properly and made to last.

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