Mississauga Accessory Structure Site Plan for Permit

A shed, gazebo, or detached garage can make a Mississauga property more useful by adding storage, covered outdoor space, vehicle parking, or workshop space. Before purchasing a prefabricated structure or preparing a concrete foundation, however, homeowners need to confirm that the proposed building will fit within the property’s zoning and permit requirements.

A clear Mississauga accessory structure site plan for permit shows the proposed structure in relation to the property lines, existing house, driveway, other buildings, setbacks, easements, landscaping, and drainage. It helps the City understand what already exists on the lot, what is being proposed, and whether the project appears to comply with the applicable rules.

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SitePlans.ca prepares clear residential site plans for sheds, gazebos, detached garages, pergolas, workshops, and other backyard structures. Plans can show property lines, setbacks, lot coverage, access, easements, grading, and existing versus proposed construction.

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Important illustration note: The dimensions shown in the image are examples, not universal Mississauga requirements.

The illustrated lot measures approximately 30.48 metres by 22.86 metres, giving it an area of about 696.8 square metres. Because that is less than 750 square metres, Mississauga’s general accessory-structure table normally allows:

a maximum of 10 m² for each accessory building or structure;
a combined maximum of 30 m² for all accessory buildings and structures;
a maximum height of 3.0 metres; and
a minimum 0.61-metre setback from interior side and rear lot lines when the structure is in the rear yard.

The illustrated 7.2 m² shed fits the general individual-size limit. The illustrated 12.9 m² gazebo exceeds that general 10 m² limit and would need to be resized or reviewed for a property-specific zoning provision or other planning approval.

The detached garage is reviewed under separate garage rules. Its illustrated 42 m² area is below the general 75 m² garage maximum and below 10% of the illustrated lot area. The actual property zone and any exception provisions must still be confirmed.

What Is an Accessory Structure?

An accessory structure is a secondary building or structure that supports the main residential use of a property.

Common examples include:

storage sheds;
garden sheds;
gazebos and pavilions;
pergolas and arbours;
greenhouses;
workshops;
pool cabanas;
outdoor fireplaces;
other freestanding backyard structures.

Mississauga’s Zoning By-law treats a detached garage separately from ordinary accessory buildings and structures. The rules for garage area, height, lot coverage, setbacks, and distance from the house are therefore different from the rules that apply to a shed or gazebo.

For a broader overview of Ontario permit drawings, review our Ontario site plan services guide.

Which Accessory Structures Need a Building Permit?

The building-permit threshold depends on the type, size, use, and construction of the structure.

Project	General Mississauga permit guidance
Storage shed	A shed smaller than 15 m² may be exempt when it is freestanding, one storey, used only for storage, and contains no plumbing. A larger shed or any shed containing plumbing requires a permit.
Gazebo	A gazebo greater than 10 m² requires a building permit. A gazebo of 10 m² or less is listed as permit-exempt, but zoning still applies.
Detached garage	A detached garage requires a building permit.
Other structure	A building or structure other than a qualifying shed generally requires a permit when it exceeds 10 m² or contains plumbing.

Permit exemption does not mean zoning exemption. A small shed or gazebo must still comply with the City’s rules for location, area, height, setbacks, lot coverage, and any property-specific zoning provisions.^[1]

Check the Property’s Zoning Before Choosing a Structure

Mississauga does not apply one identical accessory-building rule to every property. The City advises homeowners to review both:

the general residential provisions in the Zoning By-law; and
the regulations and exception provisions for the property’s specific zone.

Where a property-specific zoning rule conflicts with a general provision, the property-specific rule applies.^[2]

The zoning review may affect:

whether the structure is permitted;
maximum structure area;
combined accessory-building area;
lot coverage;
maximum height;
permitted yard;
interior and exterior side-yard setbacks;
rear-yard setback;
distance from the main house;
greenland-zone setbacks;
driveway and parking arrangements.

The City’s property-information tool can be used to identify the applicable zoning designation and related regulations.

General Shed and Gazebo Size Rules

Mississauga’s general accessory-building table divides residential lots into two size categories.

Lots Smaller Than 750 m²

For a lot smaller than 750 square metres, the general limits are:

maximum area per accessory structure: 10 m²;
maximum combined area: 30 m²;
maximum height: 3.0 m;
rear-yard side and rear setback: 0.61 m.

Lots of 750 m² or Larger

For a lot of at least 750 square metres, the general limits are:

maximum area per accessory structure: 20 m²;
maximum combined area: 60 m²;
maximum combined accessory-structure coverage: 5% of the lot;
maximum height: 3.5 m;
rear-yard side and rear setback: 1.2 m.

These provisions apply to ordinary accessory buildings and structures such as sheds and gazebos. A detached garage has its own rules.^[3]

The Illustrated Shed

The shed shown in the image measures approximately 3.0 metres by 2.4 metres:

3.0 m × 2.4 m = 7.2 m²

Because the illustrated lot is smaller than 750 m², the general individual accessory-structure limit is 10 m². The illustrated shed therefore fits within that general size limit.

It may also qualify for Mississauga’s storage-shed building-permit exemption because it is smaller than 15 m², provided that it is:

freestanding;
one storey;
used only for storage;
without plumbing; and
otherwise compliant with zoning.

The 1.2-metre setbacks shown around the shed are larger than the general 0.61-metre rear-yard setback for a lot under 750 m². A homeowner may choose a larger setback to provide better maintenance access, drainage, and separation from fences or landscaping.

The Illustrated Gazebo

The gazebo shown in the image measures approximately 3.6 metres by 3.6 metres:

3.6 m × 3.6 m = 12.96 m²

That creates two separate issues:

The gazebo is larger than 10 m², so a building permit is required.
On the illustrated lot, the general zoning provision limits an individual accessory structure to 10 m².

Obtaining a building permit does not automatically solve a zoning non-compliance. The permit application must also comply with zoning, or the design may need to be revised or reviewed through an appropriate planning process.

A practical standard design for this illustrated property would generally keep the gazebo at or below the permitted zoning area unless the property’s particular zone allows something different.

Detached Garage Rules Are Different

Mississauga regulates detached garages separately from sheds and gazebos.

Under the general garage table, a detached garage may be subject to the following limits:

maximum floor area: 75 m²;
maximum garage lot coverage: 10% of the lot area;
maximum sloped-roof ridge height: 4.6 m;
maximum flat-roof height: 3.0 m;
maximum eave height: 3.0 m;
minimum distance from the dwelling: 1.2 m.

A detached garage is not permitted between the front wall of the dwelling and the front lot line under the general provision.

For a detached garage situated in the rear yard, the usual minimum interior side and rear setbacks are:

1.2 m where the lot area is at least 750 m²;
0.61 m where the lot area is less than 750 m².

The exterior side-yard and some interior side-yard requirements depend on the regulations of the property’s applicable zone.^[3]

The Illustrated Detached Garage

The detached garage shown in the image measures approximately 6.0 metres by 7.0 metres:

6.0 m × 7.0 m = 42.0 m²

The illustrated lot is approximately 696.8 m², so 10% of the lot is approximately 69.7 m². The 42 m² garage is below both the general 75 m² floor-area limit and the general 10% garage-coverage limit.

The 1.2-metre property-line setbacks shown in the image are larger than the general 0.61-metre rear-yard setback for a lot under 750 m².

The site plan must also show at least 1.2 metres between the garage and the existing dwelling. That distance is not clearly labelled in the illustration and should be added to a real permit submission.

Can a Property Have Both an Attached and Detached Garage?

Mississauga’s general residential garage provisions permit only one attached garage or one detached garage per lot, except in certain residential zones specifically identified by the bylaw.

A homeowner whose house already contains an attached garage should not assume that a second detached garage is permitted. The current property zoning and any applicable exception schedule must be checked before the project is designed.

Where Can an Accessory Structure Be Placed?

Ordinary accessory buildings and detached garages are generally not permitted between the front wall of the dwelling and the front lot line.

Most projects are therefore located:

in the rear yard;
in a permitted interior side yard; or
in another location specifically allowed by the property’s zone.

On a corner lot, the boundary beside the second street is an exterior side lot line. The exterior side-yard rules of the applicable zone apply, and they may require a greater setback than an ordinary interior side boundary.

The site plan should label every yard and street frontage clearly. A box placed somewhere behind the house without setback dimensions is not enough.

What Must a Mississauga Accessory-Structure Site Plan Show?

Mississauga provides a detailed site-plan checklist for sheds, gazebos, and detached garages. Drawings must clearly distinguish existing conditions from proposed construction, use metric dimensions, and be prepared to scale.^[4]

The site plan must include:

metric drawing scale;
north arrow;
municipal address;
legal description, including lot and plan numbers;
dimensioned property lines;
existing buildings and accessory structures;
proposed structures, hatched and clearly labelled;
overall dimensions of each proposed structure;
setbacks from every property line;
rights-of-way and easements;
landscaped areas;
driveways, walkways, patios, and other hard surfaces;
lot area and frontage;
lot coverage in square metres and percent;
a breakdown of the areas included in coverage;
driveway width and property-line setback;
driveway surface treatment;
walkway dimensions;
established-grade calculation and calculation points.

For a broader overview of the purpose of this type of drawing, see our Canada site plan guide.

Property Lines and Legal Description

Setbacks must be measured from the property lines, not from a fence, hedge, lawn edge, driveway, or neighbouring structure.

An old fence may be:

inside the property boundary;
partly on the neighbouring property;
located within an easement;
unrelated to the legal boundary.

A property survey prepared by an Ontario Land Surveyor can be useful where:

the proposed structure is close to a lot line;
the boundary cannot be confidently located;
the property is irregularly shaped;
an encroachment may exist;
the City requests survey-based information.

A drafted site plan can show the proposed project layout, but it does not replace a legal survey when a boundary must be established or certified.

Show All Existing Structures

The site plan should show every existing structure that affects zoning, setbacks, access, or lot coverage.

Examples include:

the main house;
attached garage;
detached garage;
existing sheds;
gazebos and pergolas;
covered decks and porches;
pool cabanas;
greenhouses;
other accessory buildings.

Do not omit a small existing shed simply because it did not require a building permit. Its area may still be included in the combined accessory-structure or total lot-coverage calculation.

Lot Coverage

Lot coverage compares the applicable building area with the total lot area.

The site plan should show:

total lot area;
house footprint;
attached garage area;
detached garage area;
each shed, gazebo, and accessory-structure area;
other covered structures included by the zoning definition;
total proposed coverage in square metres;
total proposed coverage as a percentage.

The applicable zone’s maximum lot coverage includes the combined area of accessory buildings and structures as well as a detached garage.

For lots of at least 750 m², the general accessory-structure table also limits the combined area of ordinary accessory buildings and structures to 5% of the lot. Detached garages have a separate general 10% garage-coverage limit.

Because several calculations can apply at once, showing only one total percentage may not provide enough information.

Combined Accessory-Structure Area

For the illustrated lot, the shed and gazebo together occupy approximately:

7.2 m² + 12.96 m² = 20.16 m²

That is below the general combined 30 m² limit for a lot smaller than 750 m². However, the gazebo still exceeds the separate 10 m² maximum for each individual accessory structure.

This is a good example of why both individual structure area and combined structure area must be shown.

Height and Established Grade

Accessory-structure height is measured in relation to grade. A structure that appears to meet the height limit on a manufacturer’s brochure may exceed it once placed on a raised base, concrete curb, platform, or sloped yard.

Mississauga asks permit applicants to provide:

the established-grade calculation;
the points used for that calculation;
finished-floor levels;
height to the eaves;
height to the highest roof ridge;
roof shape and slope.

The general maximum height for an ordinary accessory structure is:

3.0 m on a lot smaller than 750 m²;
3.5 m on a lot of at least 750 m².

A detached garage may be higher under the separate garage rules.

Setbacks Should Be Measured to the Correct Part of the Structure

The wall footprint, roof overhangs, eaves, gutters, posts, and foundations may not all occupy the same area.

A site plan should clearly show:

outside wall dimensions;
post locations for a gazebo or pergola;
roof-overhang dimensions;
foundation or slab dimensions;
setback dimensions to the relevant building edge.

The construction drawings should match the footprint shown on the site plan. A permit reviewer should not see one set of dimensions on the site plan and a different set on the floor or roof plan.

Greenland-Zone Setbacks

Additional setbacks may apply where a residential property is beside land zoned Greenlands.

Mississauga’s general residential provisions require buildings, structures, parking areas, and pools to be set back the greater of:

5.0 metres from land zoned G1 or G2; or
the otherwise required yard or setback.

Homeowners beside ravines, woodlands, valleys, watercourses, or other protected lands should check the zoning map before choosing a backyard location.

Rights-of-Way and Easements

Mississauga’s site-plan checklist requires rights-of-way and easements to be shown.

A property may contain registered areas for:

storm drainage;
sanitary sewers;
water services;
hydro or telecommunications;
access;
maintenance;
other municipal or private purposes.

An open section of backyard is not necessarily available for construction. A permanent shed, garage foundation, gazebo footing, or concrete slab may interfere with access to underground infrastructure.

The registered document should be reviewed when the proposed structure is within or close to an easement.

Driveway and Garage Access

A detached garage site plan should show the complete vehicle route between the street and the garage.

Include:

driveway width;
distance between the driveway and adjacent property lines;
driveway surface;
garage-door location;
parking or manoeuvring space;
walkways connected to the driveway;
gates and fences;
street, sidewalk, curb, and boulevard where relevant.

Mississauga also limits the number and maximum width of driveways in many residential zones. A garage proposal should not assume that additional pavement or another driveway will automatically be approved.

Pedestrian Access

Sheds and gazebos also need practical pedestrian access.

The plan may show:

a side-yard walkway;
gate location and width;
path from the house;
clearance in front of doors;
stairs or changes in grade;
nearby retaining walls and fences.

A structure may fit within the required setbacks but still be inconvenient if tools, lawn equipment, furniture, or construction materials cannot reach it.

Drainage and Roof Runoff

A shed, gazebo, or garage adds roof area and can change how water moves through the backyard.

The completed project should not direct runoff toward:

the neighbouring property;
the house foundation;
a neighbouring building;
a public sidewalk;
a low area where water may pond or freeze.

The site plan and elevations may show:

roof-slope direction;
eavestroughs;
rainwater leaders and downspouts;
surface-drainage arrows;
swales;
existing and proposed grades;
permeable landscaped areas.

Mississauga specifically asks for rainwater leaders and eavestroughs on the permit elevations for accessory structures.

Trees, Landscaping, and Hard Surfaces

The City’s site-plan checklist requires landscaped areas and hard surfaces to be identified.

The drawing may show:

lawn and planting beds;
existing trees;
trees near the proposed foundation;
driveways and walkways;
patios and concrete slabs;
retaining walls;
construction access.

A project should be positioned so excavation, concrete placement, and equipment access do not unnecessarily damage trees or block established drainage routes.

What Other Drawings Are Required?

The site plan explains where the structure will be placed. It does not replace the detailed construction drawings.

Depending on the project, Mississauga may also require:

floor plan;
foundation plan;
roof plan;
structural framing information;
elevations for every side;
building sections;
door and window sizes;
foundation and footing specifications;
roof-slope and ventilation details;
exterior cladding and flashing information;
exposed-building-face calculations;
engineering where applicable.

The City requires drawings to be submitted through its online ePlans process and may request additional information during review.^[4]

Can a Shed or Garage Be Used as Living Space?

A standard shed, gazebo, or garage approval does not authorize the structure to be used as a separate dwelling, bedroom, rental unit, or garden suite.

Habitable use can trigger different requirements for:

zoning and permitted use;
building height and area;
fire-department access;
plumbing and servicing;
energy efficiency;
fire separation;
windows and emergency exits;
parking;
municipal addressing.

A homeowner planning a detached residential unit should follow Mississauga’s additional-residential-unit process instead of applying for an ordinary storage shed or garage.

Common Accessory-Structure Site Plan Mistakes

Permit applications are often returned because the site plan is incomplete or because a generic rule was applied to the wrong property.

Common mistakes include:

using 1.2 m as the universal setback for every structure;
not checking whether the lot is above or below 750 m²;
showing a gazebo larger than the zoning maximum;
confusing the shed rules with the detached-garage rules;
not showing the distance between a garage and the house;
omitting existing sheds and gazebos from the combined-area calculation;
not showing lot coverage in both square metres and percent;
using a fence as the property line;
forgetting roof overhangs;
leaving easements off the plan;
not showing the driveway and garage access route;
failing to provide established-grade information;
using dimensions that conflict with other drawings;
submitting an unscaled aerial screenshot.

If an application has already been returned, our guide to correcting missing site plan information explains how to address unclear property lines, setbacks, proposed work, access, easements, and coverage calculations.

When Might You Need a Survey or Engineer?

A standard drafted site plan may be suitable for many residential projects, but additional professional information may be required when:

the property lines cannot be verified;
the structure is very close to a boundary;
an easement or encroachment is involved;
the yard has a significant slope;
a retaining wall or substantial fill is proposed;
the structure has unusual foundations or framing;
the gazebo or garage exceeds prescriptive construction limits;
certified grades or elevations are required;
the City requests engineering or survey information.

SitePlans.ca can prepare a clear site-layout drawing, but it does not replace a legal survey, zoning approval, architectural design, structural engineering, grading design, or municipal review when one of those services is required.

What Information Should You Provide?

To prepare a Mississauga accessory-structure site plan, it is helpful to provide:

the property address;
legal description, if available;
an existing survey;
lot width, depth, and area;
structure length and width;
wall, eave, and roof-ridge height;
roof-overhang dimensions;
preferred placement;
distances to the property lines;
distance from a detached garage to the house;
manufacturer or construction drawings;
photos of the yard;
a sketch or marked aerial image;
existing shed, garage, gazebo, and deck dimensions;
driveway and walkway information;
known easements and utility information;
City comments, if the application has already been reviewed.

The more reliable the starting information is, the more accurately the finished site plan can represent the proposed project.

Get a Mississauga Accessory Structure Site Plan

A good accessory-structure site plan does more than place a few shapes in the backyard. It explains how each shed, gazebo, or detached garage relates to the property lines, house, setbacks, applicable size limits, combined structure area, lot coverage, height, access, easements, landscaping, and drainage.

SitePlans.ca prepares clear residential plans for Mississauga homeowners, contractors, shed suppliers, garage builders, designers, and permit applicants.

Review our site plan drafting services for additional information about available plan options.

Ready to Prepare Your Mississauga Site Plan?

Send us your property address, structure dimensions, preferred placement, survey, photos, sketch, easement information, and any comments received from the City.

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Official Sources

Building-permit thresholds, zoning provisions, exception zones, setbacks, lot coverage, fees, and application requirements can change and can vary by property. Confirm the current zoning and permit requirements with the City of Mississauga before purchasing a structure, installing foundations, or beginning construction.