Do I Need a Permit? GTA Rules for Chimney, Roof and Venting Work

Why this question comes up so often

We get asked about permits on almost every chimney rebuild and roof replacement quote across the GTA. The honest answer is that the rules are not the same everywhere and they are not always intuitive. Some work that sounds major, like repointing an entire chimney, needs no permit at all. Other work that sounds minor, like adding a second flue liner for a new gas fireplace, can trigger both a mechanical permit and a TSSA notification depending on the municipality.

This guide separates the two systems that govern this work in Ontario: municipal building permits, issued under the Ontario Building Code by each city's building division, and gas/venting compliance, overseen provincially by the Technical Standards and Safety Authority under CSA B149.1. Getting the two confused is the most common reason homeowners either over-pay for permits they did not need, or skip one they actually did.

Roofing: when a permit applies

Most straightforward reroofing jobs, where the existing roof deck is sound and shingles are replaced like-for-like, are exempt from a building permit in Toronto and most surrounding municipalities. The moment the job involves structural changes, the picture changes.

• Reshingling over sound decking with no structural change: generally no permit required.
• Replacing damaged roof sheathing or rafters: permit required, because it affects the structural assembly.
• Adding a new roof penetration (skylight, vent stack, solar mount): permit required in most GTA municipalities.
• Raising a roofline, adding a dormer, or changing roof pitch: permit required, often with an engineered drawing.
• Flat roof recovering on a low-slope commercial or mixed-use building: permit required in nearly every case.

Chimney work: rebuild vs repair vs liner

Chimney permit rules trip up more homeowners than any other category on this list, because the difference between a permit-exempt repair and a permitted rebuild often comes down to how much of the structure above the roofline is being replaced.

Liner installation and gas appliance work under TSSA and CSA B149.1

Installing a new chimney liner, connecting a gas fireplace, replacing a gas water heater, or converting a wood-burning fireplace to gas are not municipal building permit matters in most cases. They fall under the Technical Standards and Safety Authority's oversight of fuel-burning appliances in Ontario, governed by CSA B149.1, the natural gas and propane installation code.

That means the work must be performed by a licensed gas technician (G2 or G3 depending on the appliance), and in many cases the contractor files a notification directly with TSSA rather than the homeowner applying to the city. A municipal permit can still apply if the liner installation is tied to a broader chimney rebuild that affects the structure, which is why these two systems frequently overlap on the same job.

Where the two systems overlap

A common example: converting a wood-burning fireplace to a gas insert often needs a new liner (TSSA/CSA B149.1 compliance, no municipal permit) and, if the firebox or hearth is being structurally modified, a building permit for that portion of the work. A competent contractor should be able to tell you, item by item, which parts of your project fall under which authority.

Who actually pulls the permit

In almost every case, the contractor pulls the building permit as part of the job, not the homeowner, because the permit application requires trade-specific drawings and the contractor's licence information. Homeowners doing the work themselves can pull an owner-builder permit directly from the municipality, but most GTA building divisions require proof of WSIB coverage or an owner-builder declaration and will scrutinize structural work more closely when no licensed contractor is listed.

• Contractor-pulled permit: standard for roofing, chimney rebuilds and structural work - the fee is usually included in your quote.
• Homeowner (owner-builder) permit: possible for many municipalities but requires more paperwork and does not remove your responsibility for code compliance.
• TSSA notification: filed by the licensed gas technician, not the homeowner, for gas appliance and venting work.

How the five biggest GTA municipalities differ

Every municipality in the GTA operates under the same Ontario Building Code, but each city's building division sets its own permit fee schedule, application process and typical review timeline. Requirements can also change year to year, so always confirm current rules with the specific municipality before assuming last year's answer still applies.

The real risk of skipping a required permit

Unpermitted work does not usually cause a problem the week it happens. It causes a problem later, at exactly the two moments homeowners can least afford it: selling the house and filing an insurance claim.

At resale

A structural roof repair, chimney rebuild, or added roof penetration done without a permit shows up during a buyer's home inspection or a status certificate review, and can require the seller to retroactively apply for a permit, pay a fine on top of the fee, and in some cases open a wall or roof section back up for inspection before the sale closes. Real estate lawyers across the GTA see this delay closings regularly.

With insurance

If a fire, water leak, or structural failure occurs and the insurer's adjuster finds the related work was done without a required permit, the insurer has grounds to reduce or deny the claim on the basis that the work was not done to code. This applies most often to chimney rebuilds and structural roof repairs, since those are the categories most closely tied to fire and structural safety.

A quick decision checklist before you start

1. Is the roof deck or structure being touched, or only the shingle/membrane surface? Structure touched means permit; surface only usually does not.
2. Is the chimney work above or below a certain percentage of the structure? Confirm the local threshold with the municipality.
3. Is a gas appliance or liner involved? Confirm the contractor's TSSA licence and ask what they are filing.
4. Is the project adding a new penetration, dormer, or structural opening anywhere on the roof? Assume a permit is needed and confirm.
5. Will you sell the home within the next five years? Keep every permit, inspection sign-off and TSSA notification in a folder regardless of whether it seemed necessary at the time.

Getting a straight answer for your project

The fastest way to know for certain is to describe the exact scope of work to your municipality's building division or to a contractor who pulls permits regularly in your city. A five-minute phone call before the work starts is far cheaper than an after-the-fact permit application with a fine attached.