Legal basements

What Drawings Are Required for a Basement Permit in Ontario?

The drawings usually prepared for an Ontario basement permit: floor plans, sections, egress, fire separation, HVAC and who can sign them.

By Residence Redefined · Ontario homeowner guide

The short answer

Most Ontario basement permit applications are supported by a set of scaled drawings: an existing and proposed floor plan, a building section, construction notes and details, and often a site or key plan. A basement apartment usually needs more detail, such as fire separations, exits, smoke alarms and ventilation. Your municipality sets the exact list, so check its application checklist before you submit.

Drawings start with accurate measurements of the existing basement: ceiling heights, windows, beams, ducts and stairs.
A second unit adds design questions a rec room does not, like fire and sound separation, exits and separate ventilation.
Drawings must be prepared by someone permitted under the Ontario Building Code, such as a qualified BCIN designer, architect or engineer, unless an exemption applies.

Basement living area illustrating a finished residential interior — A finished appearance alone does not establish approval as a separate dwelling.

Why the drawings come before everything else

A building permit application is reviewed against the drawings. The examiner checks what you propose to build, not what a contractor promises on site. Clear, complete drawings help the review and give every contractor the same scope to price.

If you are not sure whether your project needs a permit at all, read do you need a permit to finish a basement in Ontario first.

The core drawing set for a basement permit

Requirements vary by municipality and scope, but a typical residential basement set includes the sheets below.

Existing basement floor plan: walls, stairs, windows, mechanical equipment and measured ceiling heights.
Proposed floor plan: new rooms, doors, washrooms, labelled room uses and dimensions.
Building section: floor-to-ceiling heights, insulation, wall and floor assemblies.
Construction notes and details: framing, beams or headers where walls change, and wall assemblies.
Site or key plan where the municipality asks for it, often for a new entrance or exterior change.
Supporting forms, such as designer information (schedule 1 under the Building Code) and HVAC design where required.

Explore our legal basement design & permit service →

Extra drawings for a legal basement apartment

A self-contained second unit is assessed as a separate dwelling, so the drawings need to show how it meets those requirements. See our guide on how to make a basement legal in Ontario for the wider process.

Expect the drawings to address the items below. The exact standards depend on the Building Code provisions that apply to your house.

Fire separation between units, including ceiling and wall assemblies and doors.
Exits and egress: the path out of the unit, and bedroom window sizes.
Interconnected smoke alarms and carbon monoxide alarms.
Sound separation between units.
Ventilation and heating layout, including any separate system or duct changes.
A separate entrance, if added, with its stair and landing details.

Measurements that decide what is possible

Many basement designs succeed or fail on a few numbers: ceiling height under beams and ducts, window sizes, and the stair. These are measured before design, so problems surface on paper, not after framing.

Zoning matters too. Whether a second unit is permitted, and parking or entrance rules, are set by your local zoning by-law. Check zoning before paying for full construction drawings.

Who can prepare and sign basement permit drawings?

In Ontario, designers who prepare permit drawings must generally be qualified and registered, for example a BCIN designer with the right category, an architect or an engineer. Some homeowners can design their own house. Our guide to building permit drawings and BCIN designers explains how to check a designer on the provincial registry.

Structural changes, like removing a bearing wall or enlarging a window opening in a foundation wall, may need engineering input in addition to the designer's drawings.

Check your municipality's checklist

Each municipality publishes its own application requirements and forms, and these change. Download the current checklist before you submit.

For local pages, see Brampton legal basement permit drawings, Mississauga basement permit drawings and Caledon and Bolton basement permit drawings.

Drawings first, then contractor quotes

With a complete drawing set, contractors quote on the same scope. That makes quotes easier to compare and reduces surprises once work starts.

Electrical work is separate from the building permit. In Ontario, electrical notifications and inspections are handled through the Electrical Safety Authority.

Official sources & further reading

This is general planning information, not a property-specific code assessment or an assurance of approval. Requirements depend on the building, proposed use, applicable Building Code provisions and local zoning. Your municipality makes permit and inspection decisions.