Second-storey and rear additions in Toronto, designed around your lot.

Yes. Any addition to a house, semi or townhouse needs a building permit from Toronto Building, applied for through its online Application Submission Tool with a full permit set: site plan on a survey, floor plans, roof plan, elevations, sections, construction details, the Energy Efficiency Design Summary and the Application to Construct or Demolish form. Additions of 100 m² or more to a detached or semi-detached house also need a Residential Infill Public Notice posted on site.

Toronto Building's 2026 rate for houses, semis, townhouses and duplexes is $18.56 per m² of floor area, with a $214.79 minimum. A Zoning Applicable Law Certificate (the City's written confirmation that the zoning allows the work), when one is needed, is $644.38. If work starts before the permit issues, the City adds 50% of the permit fee or $214.79, whichever is greater, to a maximum of $29,456.99. These are paid to the City at submission and are separate from our fee.

In Residential Detached (RD) zones the limit comes from the Height Overlay Map; where the map sets no height for your lot, the maximum is 10.0 m from established grade (the ground level the by-law measures height from). Main walls are capped lower: 7.0 m or 2.5 m below the maximum height, whichever is higher, so 7.5 m under a 10.0 m limit. The cap applies to at least 70% of each side main wall, or to 40–60% of the front and rear walls depending on frontage, and it is the rule that shapes most second-storey roofs. Semi-detached (RS), townhouse (RT) and multiple (RM) zones have their own figures. We confirm your zone and overlays in the written zoning review before design starts.

For a detached house on an RD lot with required frontage of 18.0 m or less, By-law 569-2013 caps building length at 17.0 m. It also keeps the rear main wall within 19.0 m of the required front yard setback. Lots with more than 12.0 m and up to 18.0 m of required frontage get one exception: a one-storey part may go 2.0 m beyond the length cap if it is no more than 5.0 m high, is no wider than half the house and sits at least 3.0 m from each side lot line. Narrower lots do not get it. The rear yard must still be the greater of 7.5 m or 25% of lot depth. Semi-detached (RS) zones carry their own version in Chapter 10.40; deep lots and other zones differ.

Often, yes. By-law 569-2013, s. 10.5.40.71, lets an addition built above a lawfully existing house on a lot with frontage of 12.2 m or less keep the house's lawful setbacks. A rear addition on a narrow lot often can too: under 9.0 m of frontage, a rear or side addition may keep the lawful side setback, and from 9.0 to 12.2 m it may use the greater of half the required side yard or the lawful setback. Outside those cases an addition meets today's setbacks or needs a minor variance from the Committee of Adjustment. “Lawfully existing” means the house was authorized, or had its permit issued, by June 26, 2025. Whether your setback qualifies is one of the first things the zoning review checks.

It goes to the Committee of Adjustment. The 2026 application fee for additions and alterations to a dwelling with three units or fewer is $2,228.98, double for after-the-fact variances, and applications are submitted by email as PDFs with the City's forms, a Tree Declaration form and photos of the front and rear yards. We prepare the package, the plans and the rationale, and present at the hearing. Since November 28, 2022, only the applicant, the Minister, specified persons and public bodies can appeal a decision.

Architalcan's office prepares the drawings, and they are signed under BCIN 25897 – 41741 (House, Small Buildings, Large Buildings, HVAC-House). Toronto Building requires drawings prepared by a qualified designer to show the designer's name, registration number, qualification number, signature and a statement accepting responsibility for the design; ours do. Sheets that need an engineer carry the engineer's seal and are filed with the City's Assumption of Responsibility for Engineering Content form.