The Cause of Backdrafts

Published on September 24, 2018


What is this smoke billowing over my fireplace?

Some of your home’s problems are more obvious than others, but that doesn’t always make them easier to decipher. Take those blackened smoke stains above your woodstove, or your fireplace, as an example – or that strange white substance that is forming on top of your water heater. These could be symptoms of backdraft (no, not that movie from ‘91 about firefighters – although, backdrafting has become synonymous with explosions and out of control fires). Still, there’s something we can’t see that’s also a dangerous by-product of backdraft, and that’s carbon monoxide. This is why finding the cause of backdrafts in a home is crucial to your health and safety.



The Cause of Backdraft

Many appliances in a home, such as a gas water heater, boiler, furnace, woodstove and fireplace, use combustion to function. During combustion, carbon monoxide is produced and released to the outside through a flue or a chimney. However, if there’s more air being pushed out through the home elsewhere, such as an open window, an exhaust fan, or leaks in the ceiling of your top floor, your home will naturally try to replace that air by drawing more in – including from the chimney or flue – in an attempt to balance the indoor pressure.


If you have recently renovated your home by improving your insulation and air sealing, you may have actually made it too tight for your mechanical systems to do their job properly. Consulting with home renovation experts will help you avoid this potential issue. To counteract this, you need to make sure your air exchange system, whether it is an HVAC, HRV or ERV, is working to keep the indoor air pressure balanced. If your home has been made air tight, your system may now be too powerful; if your home is too leaky, your system may not be powerful enough (note: it’s better to have a well-insulated, air tight home with the right sized system than a leaky home with an overworked system). Even in a new home, you may run into backdrafting for the same reason.



Backdraft Prevention

It might seem like there’s no way to win, but there are ways to fight backdraft. In some cases, backdraft can be due to a malfunctioning valve, which could be easy to fix. However, in many cases, you need to find the hidden source of the problem. The process involves an exhaust device depressurization test. This test pinpoints the exact reason for backdraft be occurring in your home, and will help you determine exactly how to solve it. Backdrafts are harmful and dangerous to yourself, your family, your pets (yes, they are often considered to be family too!), and your home.


If you’re seeing symptoms of backdrafts, it’s better to at least have a consultation with a professional to determine if it should be looked into. Barrier Sciences Group has licensed energy advisors that can speak with you about the cause and effects of backdraft, perform an exhaust depressurization test to find its source, and help you put an end to your home backdraft woes. They’re also available as your personal Home Renovation Experts to help you prevent it from happening if you’re planning to renovate your home.


Call 1-866-333-3920 or fill out the contact form to get started today.

The Canada Greener Homes Grant offers home efficiency renovation grants up to $5,000.

Homeowners Canada-wide are eligible for the Canada Greener Homes Grant, announced on May 27, 2021. This new incentive offers up to $5,000 in grants for home efficiency retrofit renovations, plus a $600 reimbursement for pre- and post-work EnerGuide evaluations. Eligible retrofit scopes include home insulation, heating, doors, windows, photovoltaic solar panels, resiliency measures, and thermostats.

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