Lot Severance and Multiplex Development in Ontario: Unlocking Maximum Density for Your Properties

Introduction

The landscape of residential development in Ontario has transformed dramatically in recent years, particularly with the introduction of Bill 23 (More Homes Built Faster Act, 2022). Property owners and developers now have powerful tools at their disposal to unlock significant value from seemingly modest residential lots. Lot severance combined with as-of-right multiplex zoning represents one of the most compelling opportunities in Ontario's current real estate market, allowing single properties to be transformed into multiple development sites—each capable of housing multiple dwelling units without requiring rezoning or lengthy approval processes.

For architecture and design firms working with real estate developers, understanding how to strategically combine lot severance with contemporary multiplex development is essential. This strategy has the potential to double or even triple the residential density on a given property, creating substantial value while maintaining neighborhood compatibility.

Picture Credit: Land Severance in Ontario | Lot Severance in Toronto Guide

What is Lot Severance?

A lot severance (also called "consent to sever") is the legal process of dividing a single parcel of land into two or more separate, independent lots. Each severed lot receives its own unique property title, can be mortgaged independently, and can be sold separately. The original lot is called the retained lot, while the newly created parcels are called severed lots.

Severance is distinct from subdivision, which typically involves creating more than three new lots and requires a more complex approval process. Severance applications are processed through the Committee of Adjustment at the municipal level, making the timeline and approval requirements more manageable for property owners.

Who Needs Lot Severance?

Lot severance is essential when you want to:

• Sell a portion of your property while retaining the remainder

• Mortgage part of your property independently

• Create multiple development sites from a single parcel

• Divide property among family members

• Unlock land value through development on severed lots

Bill 23 set a new baseline for residential zoning: as-of-right permissions for up to three residential units per lot province-wide, many cities have gone even further. For example, Hamilton and Toronto allow fourplexes as-of-right; meaning, if your severed lot meets local size requirements and zoning, you can build four units per parcel, with no time-consuming rezoning or Committee of Adjustment process needed.​

Hamilton Example:

• Original lot: 25m wide

• After severance: Two lots, 12.25m each

• Result: You can build a fourplex on each—eight units instead of four, doubling density and rental or resale potential.​

Toronto Example:

• Severance can transform a single-family 60' lot into two 30' parcels, each supporting significant density (such as two six-unit multiplexes, depending on area).

Bill 23 and As-of-Right Multiplex Zoning

Why Severance + Multiplex Zoning Matters

Advantages:

• More units: Dramatically increase housing supply and property value

• No rezoning: Approval process is faster, simpler, and avoids local opposition

• Flexible ownership: Each lot is a separate legal entity, offering refinance or sale options

Risks & Cons:

• Upfront costs: Surveys, legal, and application fees add up ($10k–$50k)

• Approval is still needed: Severance must be granted by your municipal Committee of Adjustment—local rules apply

• Infrastructure: Not all lots will have the services (sewer, water) or parking needed for maximum density​

• Neighborhood Context: Some areas may be more or less receptive to multiplex infill, so best practices include early consultations with planners and neighbors

Best Practices for Success

• Start with a pre-consultation: Engage your municipality’s planning staff before investing heavily

• Do your homework: Check zoning, servicing, and historical lot patterns; involve an Ontario Land Surveyor early

• Document everything: Lot sketches, planning rationale, and servicing letters make for smoother approvals

• Work with professionals: Architects, planners, and real estate lawyers are key

• Design with the future in mind: Ensure your multiplex plans fit both regulations and market needs

Bottom Line

Severance plus as-of-right multiplex zoning is a game-changer for Ontario’s property owners, builders, and investors. With thoughtful planning and expert support, a single lot can be transformed into several homes, creating value for owners and much-needed housing for communities.

If you're curious how these strategies could work for your property, let's connect! Our team specializes in feasibility analysis, severance applications, and elegant multiplex designs that maximize value and fit the character of your neighborhood.