Shed Permits and Snow Loads in Canada

Building a shed in Canada is the same job as building one in the US: the same 2x4 studs, the same 4x8 sheets, the same feet and inches on the tape. Two things change, and both decide what you can build. A shed permit in Canada is set in square metres, usually 10 m² or 15 m², by your city. And the snow your roof has to carry comes from the National Building Code of Canada, in kilopascals, and in much of the country it is heavier than the numbers US plans assume.

This guide covers both. The first half shows where the permit line sits in six Canadian cities, with the shed sizes that fit under 10 m² and 15 m². The second half turns the code’s snow data into a roof load you can type into the shed designer, with a table for 58 cities. For the general picture of permits, zoning and setbacks, start with our shed permit basics.

Do you need a permit for a shed in Canada?

There is no single national rule. The National Building Code of Canada is a model code: provinces and territories adopt it, with or without changes, and cities run the permits. The NBC itself tells builders to ask the province or territory which building code applies. So the answer to “do I need a shed permit in Canada” is always a local one, and the cities below show how far apart they can be.

Toronto and Ottawa: up to 15 m²

The City of Toronto says a shed under 15 m² does not need a building permit, and it quotes the code text behind that rule: the shed must be no more than 15 m² in gross area, one storey, not attached to any other building or structure, used only for storage for the main building on the lot, and without plumbing. Other accessory buildings, such as a detached garage, workshop or cabana, need a permit above 10 m². Toronto also says that zoning still applies when no permit is needed.

Ottawa uses the same 15 m² line for one-storey detached accessory buildings without plumbing and gives it as 162 sq ft, while Toronto writes 161 sq ft. The exact figure is 161.5 sq ft, so plan for 161 and do not build to the last inch.

Calgary and Edmonton: 10 m²

The City of Calgary requires a building permit for a shed, gazebo, greenhouse, workshop or similar accessory building larger than 10 m² (107 sq ft). Under 10 m², a permit is typically not needed, but the building still has to follow the Land Use Bylaw’s rules on where it sits and how it is built.

Edmonton draws the same 10 m² line (it writes 108 sq ft) and spells out the conditions: not attached to the house, no electricity, plumbing or gas, the roof midpoint no higher than 4.3 m, and 0.6 m from an interior side property line. Kits and pre-assembled buildings over 10 m² need a permit too.

Montreal: it depends on the borough

The City of Montreal handles sheds borough by borough. Its page says a permit may be needed and asks you to contact your borough before you buy or install a shed. On the same page, several boroughs allow a shed of up to 15 m² without a permit, with their own height and distance rules, while others ask for a certificate of authorization for any shed at all. Pick your borough on montreal.ca before you plan the size.

British Columbia: 10 m² in Richmond

The City of Richmond, next to Vancouver, lets you build a shed of up to 10 m² (107 sq ft) without a building permit, and says the minimum setbacks still apply. We could not read the City of Vancouver’s own page for this guide, so if you build in Vancouver, confirm the number with the city before you rely on Richmond’s.

Which shed sizes fit under 10 m² and 15 m²

Shed plans are sold in feet, so convert before you pick one. One square metre is 10.764 sq ft, which puts 10 m² at 107.6 sq ft and 15 m² at 161.5 sq ft. Here are the sizes from our free shed plans:

The named size is the frame of the shed. Siding and trim add a little on every side, and a 10x16 at 14.9 m² has almost nothing to spare. Ask your city how it measures gross area before you build right at a limit. The 10x12 gable shed is the classic size that lands between the two lines: permit-free in Toronto, a permit in Calgary.

Permit or not, zoning still applies

Every city above says the same thing in different words: a shed that needs no building permit still has to meet the zoning bylaw. Setbacks from the lot lines, height, lot coverage and where on the lot a shed may sit are all zoning rules, and they apply at any size. Services matter too: the Toronto, Ottawa and Edmonton exemptions all require a shed without plumbing, and Edmonton’s also rules out electricity and gas.

Snow loads: why Canadian sheds need a bigger number

The designer starts at 30 psf of snow. By the code’s formula that covers Toronto, Calgary and Vancouver, and it falls short in Ottawa, Montreal and Quebec City. You can choose from 20 to 80 psf, and this section shows how to find the right number for your city.

How the code turns ground snow into a roof load

The National Building Code of Canada 2020 lists two numbers for each place in its Table C-2: Ss, the ground snow load with a 1-in-50 chance of being exceeded in any year, and Sr, the rain that can fall on that snow. For houses and small buildings (Part 9 of the code), Article 9.4.2.2 turns them into a roof load:

S = Cb x Ss + Sr

Cb is 0.55 for most roofs and 0.45 when the entire width of the roof is 4.3 m (about 14 ft 1 in) or less. The result is never less than 1 kPa. The table below uses 0.55, the larger factor, because it is the safer starting point and it does not depend on how your building department measures a roof’s width. Ask them whether your roof qualifies for 0.45.

From kilopascals to psf

The designer works in pounds per square foot. One kilopascal is 20.885 psf, so multiply. The code’s minimum of 1 kPa is 20.9 psf, which is why the table below never shows less than that, and why even Toronto rounds up to the 30 psf option.

Snow loads for 58 Canadian cities

Pick your city to see the roof load and open the designer at the matching setting. The designer option is always the next one up, never down.

The largest value in this list is 55.0 psf, for Corner Brook and Gander. Across all the rows we read from Table C-2, 611 of 680 places come out at 50 psf or less and 673 at 80 psf or less.

A worked example: Quebec City

Table C-2 gives Quebec City Ss = 3.6 kPa and Sr = 0.6 kPa. The roof load is 0.55 x 3.6 + 0.6 = 2.58 kPa, and 2.58 x 20.885 = 53.9 psf. The next designer option is 60 psf.

Try it on a big shed. A 16x20 gable shed with rafters at 24 inches on center gets 2x6 rafters up to 50 psf, and the designer moves it to 2x8 rafters at 60 psf. At 16 inches on center the same shed keeps 2x6 rafters all the way to 80 psf. Open the 16x20 at 60 psf to see the span check and the lumber list change.

When your town is not on the list

The table above is a selection. Table C-2 lists design data for over 600 places, and the code warns against interpolating between them in complex terrain; for places not in the table it points to Environment and Climate Change Canada. Mountain towns in British Columbia sit far above our range: by the same formula Revelstoke works out to 84.8 psf and Whistler to 127.9 psf, past the designer’s 80 psf limit. If your number is over 80 psf, have the roof designed for you.

Rafter sizes at Canadian snow loads

The NBC has its own span tables, and one of the species groups in them is Spruce-Pine-Fir: they list rafter spans for SPF No. 1 and No. 2 at specified snow loads from 1.0 to 3.0 kPa. The designer does its own math with US design values for SPF No. 2: your snow load plus 10 psf of roof dead load, the bending strength of the board, and a sag limit of the span divided by 180 (240 on a lean-to at 3/12 or flatter). It tries 2x6, then 2x8, 2x10 and 2x12, and keeps the first one that passes.

How the designer compares with the NBC span table

We checked the designer against the NBC 2020 tables for every size from 2x4 to 2x12, at 12, 16 and 24 inches on center and at all five snow loads. In every cell the designer’s span is equal to the table’s or shorter: between 82% and 100% of it. Here is the 2x6 rafter at 16 inches on center (the NBC column is 400 mm):

So the designer is a little more cautious than the Canadian table, never less. It is still a planning aid: the NBC tables come with their own conditions, and the code your province adopted is the one your inspector will use. The shed rafters guide explains how the span check works.

What changes at heavy loads

On most shed sizes the rafters do not change at all: every one of our 20 plans keeps 2x6 rafters at 16 inches on center even at 80 psf. What changes first is a wide opening in a wall that carries the roof. A lean-to carries its whole roof on the front and back walls, so a wide door there gets a deep header, and at the heaviest loads a very wide door in a deep lean-to cannot be framed with a doubled 2x12. The designer then tells you to narrow the opening or move it to a gable end wall.

Building your shed in Canada with the designer

Everything else in the designer is the same in Canada. Walls are framed with 2x4 studs at 16 or 24 inches on center, sheathing and siding come in 4x8 sheets, and the cut list and shopping list are in feet and inches. Set the snow load from the table above, set the size under your city’s permit line, and the plan follows. The 8x10 gable shed is a size that stays under 10 m² anywhere on our list.

For the whole build, from the base to the roof, read how to build a shed. Before you dig, ask your utility locate service to mark the lines. And before you buy lumber, make one call to your municipality: ask for the permit limit, the zoning setbacks and the snow load they want you to design for.