Victoria Suen founded Build X Design after training at architecture and branding firms across North America and investing in multiplexes herself. That combination is rare in the missing middle space. She brings an architect’s precision to decisions that most investors only think about in spreadsheets, and works with Toronto homeowners and investors from the first design conversation through to a completed build.
Experts in new build multiplexes and conversions, top-up additions, and missing middle infill across Toronto neighbourhoods. Check out our projects throughout the Greater Toronto Area where we’ve helped hundreds of investors complete their multiplex project from concept to completion.
We take homeowners and first-time developers from idea to approvals with a clear plan for multiplex design in Toronto. Feasibility, zoning review, architectural design, and construction guidance, in one process.
All successful multiplex projects start off with the right strategy. By completing over 200 multiplex projects, we’ve seen what works and what costs investors money before they ever get to construction. We create project roadmaps before you commit so the numbers make sense before a single permit is filed or a building is purchased.
Before you design or even purchase the property, we check whether your Toronto lot can carry a fourplex, sixplex, or other multi-unit build. We research what the zoning allows, where the site fights you, and how many units realistically fit, so you’re not guessing on the deal.
We design to get more out of the lot while staying inside Toronto’s zoning and approvals rules. Our flexible architectural services help you push through the design and permitting process for any building type.
Our services go beyond the design and help you complete the construction. From concept and permitting to bidding and project completion, we’re a partner that’s on your side to provide you a full turn key solution to your investment journey.
Our work goes beyond multi-unit housing. We’ve drawn and permitted a wide range of architectural projects, and that range sharpens how we approach every multiplex.
Have a lot in mind, or a question about what’s possible? Please fill out our project intake form so we can assess your next project.
There are many factors that can effect the permit and construction timelines for a multi-unit project, but here are some rough estimates. A two-unit duplex takes four to eight months. A three-unit conversion runs six to twelve months. A full four-unit conversion with structural changes typically takes twelve to eighteen months. A new-build multiplex can take fourteen to twenty-four months. Duplex permits can be issued in one to two weeks. Triplexes and above permits take four to eight weeks due to a more intensive review process.
Designing as of right means your project meets all existing zoning and bylaw requirements without needing a minor variance application. This lets you skip the Committee of Adjustment process and move directly to building permit approval, which saves weeks or months on your project timeline and reduces approval risk.
A feasibility study evaluates a property’s zoning, lot dimensions, setbacks, building code requirements, and layout options before you commit to buying or building. It gives you a realistic picture of what the property can hold and what it will cost. Skipping this step is one of the most common mistakes first-time multiplex investors make.
No. Zoning, lot dimensions, setbacks, existing structure, and servicing all determine what a specific property can hold. A design that works on one lot cannot automatically be replicated on another. This is exactly why a property-specific assessment is the first step before spending money on drawings, permits, or construction.
As of 2026, sixplexes are currently permitted as of right in nine Toronto wards: Parkdale-High Park, Davenport, Spadina-Fort York, University-Rosedale, Toronto-St. Paul’s, Toronto Centre, Toronto-Danforth, Beaches-East York, and Scarborough North. Being in one of these wards is the starting point. Your lot still needs to meet zoning, setback, lot coverage, building height, and parking requirements before a sixplex is viable.
Most residential properties in Toronto can now accommodate up to four units as of right under By-law 287-2023. In nine designated wards, sixplexes are also permitted as of right. You can also add a garden suite or laneway suite in the backyard, which can bring the total to five or seven units on a single lot depending on your configuration. To find the exact amount that is allowed for your zone, please check out our free multiplex checker tool
Toronto eliminated minimum parking requirements for duplexes, triplexes, and fourplexes in 2022. You can still add parking if feasible, but it’s not mandatory for these building types.
Absolutely! Garden and laneway suites are generally additive in Toronto and don’t count toward the main-house unit cap, subject to suite bylaws and site constraints.
Missing middle refers to mid-density types between detached homes and mid-rise apartments designed to fit into residential neighbourhoods. These include duplexes, triplexes, fourplexes, sixplexes, courtyard buildings, and small townhouse clusters.
