Testing the viability of fourplexes across Toronto’s parcels

Through a comprehensive understanding of the range of Toronto’s parcel sizes and zoning laws, this study maps out lot sizes that make fourplexes viable, presents diagrammatic building plans for 1,440 lots in the city, and concludes with 9 detailed building designs.

Funded By:
Neptis Foundation

Date:
May 2022 - October 2025

Team:
Michael Piper 
Samantha Eby
Janna Levitt (LGA)
Lola Abraham
Roel Calosa
Toby Evans
Nan Liang

The Study

This report explores how four-unit multiplexes can be designed and built across a range of residential parcel sizes within Toronto. The findings and designs of this report have potential applications beyond the city.

The study was divided into 3 phases:

• Phase 1: Mapping and Diagramming
  
• Phase 2: Test Fitting
• Phase 3: Off the Shelf

Download the report here or scroll down to view it below.

Phase 1

Using a matrix of 1,440 different parcel sizes at half-meter increments of width and depth, we mapped diagrammatic floorplates that fit on each parcel. This established a foundational understanding of which parcels can support fourplex development.

Zoning restrictions - Front yard Setbacks (FYSB), Side yard Setbacks (SYSB), Rear yard Setbacks (RYSB), and Maximum Building Depths - determined the buildable footprint for each lot size. This buildable footprint defined the building envelope of the overall exterior massing a fourplex is allowed to take up. 

Four stair and unit configurations were used in design testing to determine viable lots. Unit areas smaller than 40sqm are considered to small to be viable, while 40, 70, 90, and 110 sqm represent steps that correspond to different bedroom counts.

Phase 2

The buildable footprints from Phase 1 were further developed into diagrammatic floor plans, testing how well each configuration performs on real parcels.

These diagrams test how well all the necessary rooms, services, and furniture can fit and flow on each of the lots. This helped to define which configurations would be most suitable on whit of Toronto's varied parcel sizes.

The result of this phase was a clearer sense of the feasibility boundaries for fourplex development broken down by unit size and configuration.

Phase 3

For Phase 3 of ReHousing's Fourplex Study, detailed architectural drawings were produced for 9 of the most representative diagrams from Phase 2.

Necessary architectural and functional elements for building code requirements were added, and each fourplex includes at least one barrier-free unit. These are fully realized design plans that can easily translate into construction drawing sets.

See all the designs in our S Design Catalogue

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