Second-Storey Addition Permit Drawings: What the City Requires

To obtain a building permit for a second-storey addition in Toronto, you need a complete drawing package that includes site plans, floor plans, elevations, building sections, structural drawings stamped by a licensed engineer, and construction details meeting Ontario Building Code requirements. The City of Toronto Building Department reviews these drawings to verify your addition complies with zoning bylaws, structural safety standards, and neighbourhood character guidelines. Missing or incomplete drawings are the leading cause of permit application rejections.

The Complete Drawing Package for Second-Storey Additions

A second-storey addition represents one of the most complex residential permit applications because it affects nearly every building system. Your existing foundation, walls, and connections must support the new load. The roof is removed and rebuilt. Mechanical systems often need upgrades. This complexity means the drawing requirements are extensive compared to simpler renovations.

Your submission must include architectural drawings prepared by a qualified designer and structural drawings stamped by a Professional Engineer licensed in Ontario. The City will not accept structural drawings without an engineer's seal for this type of project, regardless of the addition's size.

Site Plan Requirements

The site plan establishes your property's legal boundaries and shows how the addition relates to setback requirements. For second-storey additions, the site plan must clearly indicate the building footprint, property lines with dimensions, front, rear, and side yard setbacks, and the overall building height measured from established grade to the highest point of the roof.

• Property boundaries with dimensions from a recent survey
• Existing and proposed building footprints
• All setback dimensions to property lines
• Building height calculation from established grade
• Location of driveways, walkways, and trees requiring protection
• North arrow and scale notation

Architectural Floor Plans

You need floor plans for both the existing main level and the proposed second storey, drawn at a minimum scale of 1:50. These plans must show room layouts, door and window locations, staircase dimensions, ceiling heights, and all structural elements including bearing walls and beam locations. The existing floor plan demonstrates how your current structure will support and connect to the new level above.

Building Elevations

Elevations are vertical views of each side of your home showing the addition's visual impact. Toronto requires elevations of all four sides, clearly distinguishing between existing construction and new work. These drawings must include finished grade lines, overall building height, window and door sizes, exterior cladding materials, and roof slopes expressed as ratios.

Building Sections

Cross-sections cut through the building vertically to show internal construction details. For second-storey additions, sections must illustrate how the new floor system connects to existing walls, the staircase configuration with headroom clearances, ceiling heights on both levels, and the roof structure. Most applications require at least two sections: one through the staircase and one through a typical area of the addition.

Structural Engineering Requirements

The structural drawings are often where permit applications fail. Adding a second storey doubles the load on your existing foundation and walls. A Professional Engineer must assess whether your current structure can handle this load or needs reinforcement. Their stamped drawings become a legal document certifying the design meets Ontario Building Code structural requirements.

Structural drawings typically include foundation reinforcement details if required, existing wall assessments and any necessary upgrades, new floor framing plans with joist sizes, spans, and spacing, roof framing plans, beam and header schedules, and connection details showing how new construction ties into existing structure.

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The most common structural issue we see is inadequate existing foundations. Many Toronto homes built before the 1970s have foundations that need underpinning or reinforcement before they can support a second storey.

Your engineer will likely need to visit the property to assess existing conditions. They may require exploratory openings in walls or the basement to verify construction details not visible from the surface. Budget time and money for this investigation phase before drawing preparation begins.

Zoning Compliance Documentation

Toronto's zoning bylaws control building height, lot coverage, setbacks, and angular planes. Second-storey additions frequently trigger zoning issues because they increase height and may violate angular plane requirements designed to protect neighbours' access to light and sky views.

Your drawings must include a zoning summary table comparing your proposed design against all applicable zoning requirements. This table should list the permitted and proposed values for height, lot coverage, floor space index, setbacks, and angular planes. If any values exceed permitted limits, you need to apply for a minor variance through the Committee of Adjustment before or concurrent with your building permit application.

• Maximum building height varies by zone but commonly ranges from 8.5 to 10 metres for residential areas
• Angular planes typically start at a specified height at side lot lines and slope inward
• Floor space index limits total floor area relative to lot size
• Setback requirements may differ for first and second storeys in some zones

Neighbourhoods like the Annex, Rosedale, and parts of Leaside have additional heritage or character area guidelines that affect what designs the City will approve. Research your specific area's requirements early, as these can significantly constrain your design options.

Additional Drawing Requirements

Energy Efficiency Compliance

Ontario Building Code Section 12 requires energy efficiency measures for new construction and additions. Your drawings must include wall section details showing insulation values, window specifications with U-values, and an energy compliance summary. For larger additions, you may need to provide energy modelling documentation.

Construction Details

Standard construction details show how building components come together. Required details typically include wall assemblies, roof assemblies, window and door installation, flashing at the junction between existing and new construction, and guardrail specifications for any new decks or balconies. PermitsHub includes these standard details in all drawing packages, customized to match your specific design and materials.

HVAC and Plumbing Considerations

While not always required in the initial architectural submission, the City may request mechanical drawings if your existing heating system cannot adequately serve the addition or if you're adding bathrooms. Discuss mechanical requirements with your designer early to avoid surprises during the review process.

Common Reasons for Drawing Rejections

Understanding why applications fail helps you submit a complete package the first time. The City of Toronto Building Department commonly rejects second-storey addition applications for incomplete structural information, missing height calculations or incorrect grade references, inadequate fire separation details for homes close to property lines, non-compliant staircase designs, and drawings that don't match between architectural and structural sets.

Another frequent issue involves survey discrepancies. If your drawings reference property lines but you haven't provided a current survey, the examiner cannot verify setback compliance. For second-storey additions, an up-to-date survey is effectively mandatory, even if not explicitly listed as a requirement.

Timeline and Process Expectations

Second-storey additions typically require full plan review rather than the faster residential fast-track process. Plan on several weeks for initial review, with additional time if revisions are required. Complex projects or those requiring variances can extend timelines significantly.

The drawing preparation itself usually takes four to eight weeks for a straightforward second-storey addition, assuming the structural engineer can complete their assessment without discovering major issues. If foundation work is needed, add time for detailed underpinning designs and potentially a separate permit application for that scope.

Working with an experienced permit drawing studio like PermitsHub can reduce revision cycles because your drawings arrive at the City complete and formatted to examiner expectations. We coordinate directly with structural engineers and handle the back-and-forth communication during the review process.