Removing an unused chimney is a common decision during thermal modernization or roof replacement in Toronto, Mississauga, Oakville and other cities in 2026. Removing an unnecessary element improves the aesthetics of the house and eliminates the risk of leaks.
What to do with an unused chimney? Two proven methods of removal
Modern heating systems, such as heat pumps, often make traditional brick chimneys redundant. An unused chimney is not only a waste of space, but also a potential source of heat loss (a so-called thermal bridge) and a risk of leaks in the flashing.
If you plan to get rid of your chimney, you have two main solutions to choose from. Each has its advantages and depends on the scope of the planned renovation.
Option 1: Securing the chimney above the roof (the “slab” method)
This solution is most often chosen when we do not plan to replace the entire roof covering in the near future.
What it involves: The chimney remains in its current external form. It is cleaned and then sealed from above with a concrete cover plate or a special steel cap.
Advantages:
Low cost: No interference with the roof structure or roofing work is required.
Speed: The work can be completed in one day.
Building aesthetics: The shape of the house remains unchanged, which is important for houses with traditional architecture.
Important: Remember to leave a small ventilation opening inside the unused flue to prevent moisture condensation.
Option 2: Demolition below the roof line (“full concealment” method)
This is the most aesthetic and technically “clean” solution, ideal when replacing tiles or shingles.
What it involves: The chimney is demolished down to the attic level (below the rafters). The resulting hole in the roof is patched up – missing patches, a membrane, and new roofing (tiles or shingles) are installed in this area so that the chimney site becomes completely invisible.
Advantages:
No thermal bridge: You can thoroughly insulate the chimney site, keeping the heat inside the house.
No more leaks: You eliminate the most critical point of the roof, i.e., the flashing around the chimney.
Modern look: The roof becomes a uniform, smooth surface.
Important: This method requires spare roof tiles or matching new shingles, which may differ slightly in color from those that have been exposed to the sun for years.
Which method should you choose?
If your roof is in good condition and you don't want to incur high costs, choose the panel (Option 1).
However, if you are planning to renovate your roof or want to forget about chimney maintenance once and for all and improve the energy efficiency of your building, demolition below the roof (Option 2) will be the best investment.
Need help choosing or pricing the work? Contact us! We will professionally assess the condition of your roof and help you make the best decision.
We provide services in three cities: Mississauga, Oakville, Toronto.
