Guide
Re-roofing permits in Ontario
Whether a flat roof job needs a permit depends on the municipality and the scope of work. This guide shows how to find out, rather than guessing.
Why there is no single answer
Building rules in Ontario are set at several levels, and each municipality runs its own building department. Work that is routine in one city may need a permit, a drawing or an inspection in another. Whether you need one can depend on the type of work (a repair or a full replacement), whether the structure or insulation changes, whether the building is a house or a larger building, and whether it is in a heritage area.
The safe approach is to ask. A short call or email to the building department of your city or township gets you an answer for your address.
How to find out what applies
Find your building department
Search your municipality’s website for "building permits". In large cities there may be a district office for your area.
Describe the work clearly
Say what you plan: repair, coating, replacement of the membrane only, replacement with new insulation, or a change to the structure or slope.
Ask three questions
Is a permit needed for this work? What drawings or documents do you need? Are inspections required?
Ask about related rules
Some roof changes touch other rules: heritage districts, energy requirements for added insulation, drainage onto neighbouring land and fire rules for hot work near combustible walls.
Write down the answer
Save the email, the name and the date. Share it with the contractor before you sign.
What the City of Toronto says
Toronto is the one municipality where the rule was checked for this guide. The City’s building permit page lists "replacing existing roofing material, provided no structural work is required" among the work that does not need a building permit. Structural work, rooftop storm-water retention systems and green roofs are on the list of work that does. Check the City’s page for the current wording before you rely on it.
Toronto’s Green Roof Bylaw applies to new development and additions above a stated floor area (more than 2,000 square metres of gross floor area); the City’s page does not describe it as applying to ordinary re-roofing. For any other municipality, from Ottawa to Thunder Bay, do not assume Toronto’s answer. Ask the local building department.
Things that often come up
Number of layers on the roof
Adding a new membrane over old ones adds weight and may hide problems. Some jurisdictions and manufacturers limit layers. Ask the roofer how many are there. See repair or replace.
Insulation changes
Adding insulation or tapered layers may bring energy or structural questions. See tapered insulation.
Structural repairs
Replacing joists or large amounts of deck is usually a different level of work than replacing the membrane.
Hot work and fire safety
Torch-on work beside wood framing carries fire risk. Many contractors use cold-applied or self-adhered systems where a torch is unsafe. Ask the building department or your insurer if there are rules for your building.
Roof drains and downspouts
Changes to where roof water goes may be regulated. See roof drains and scuppers.
Condo and rental buildings
The corporation or landlord has its own approval steps in addition to any municipal ones. See condo roof planning.
Incentives that need approval first
Toronto has run an Eco-Roof Incentive Program with funding for cool roofs: $5 per square metre for a new reflective membrane or $2 per square metre for a coating over an existing roof, up to $50,000 per project, at the time this guide was written. The membrane has to meet the program’s reflectance standard, and approval must come before work begins. These are program figures, not roofing prices. Funding may be available, so check eligibility on the City’s site before you sign or start. Other cities have their own programs, or none.
Who applies and who pays
The permit applicant is typically the owner or an agent such as the contractor, and the owner remains responsible for the property. Agree in writing who will apply, who pays any permit fee and who books inspections. A contractor who says "no permit is needed" should be able to tell you who confirmed it, and for which city.
If a permit is required and the work is done without one, it can cause trouble when you sell, refinance or claim insurance. Checking first is cheap.
What to have ready when you call
The property address, roof size, the type of building, the current roof type and layers if known, and the work planned. Photos help. The details you gather for a quote are the same ones the building department will ask for; see preparing for a roof quote.
If the answer is "no permit needed"
Even without a permit, the work must still be safe and follow the manufacturer’s instructions. Ask the contractor how they will handle fire safety, drainage and layer limits, and whether the work could affect an insurance condition on your policy.
Keep the building department’s reply on file. If the rules change, or a later buyer asks, you will have a dated answer rather than a memory.
Questions about permits
Does a small repair need a permit?
Often not, but it depends on the municipality and the work. Ask before you assume.
Does the roofer handle the permit?
Some do, some do not. Settle it in the written scope. See hiring a flat roofer.
Does a coating need a permit?
It depends. Coatings are often treated differently from replacements, but the answer is local. Ask your building department.
Leak, damage or an old flat roof?
Send a few details and photos. We reply by email with next steps and a written quote.