Ontario Design Studio prepares BCIN-certified building permit drawings for duplex, triplex, and fourplex conversions across Ontario. Following Ontario's 2023 housing policy changes, up to four residential units are now permitted on most residential lots - creating significant opportunities for homeowners and developers looking to increase housing density and rental income.
Multiplex Permit Drawing Services
- Duplex conversions: Dividing a single-family home into two self-contained units
- Triplex permit drawings: Three residential units with independent fire separation, egress, and services
- Fourplex / multiplex drawings: Maximum density on residential lots under Ontario's new housing rules
- New-build multiplex designs: Purpose-built multi-unit buildings from the ground up
- Combined with secondary suites: Main house + basement apartment + garden suite configurations
Ready to start your project?
Ontario Design Studio delivers BCIN-certified, OBC-compliant building permit drawings across Ontario and the GTA. Call 416-558-9607 or request your free quote.
Key Requirements for Multiplex Permits in Ontario
Multiplex projects have more complex OBC requirements than single-unit homes. Key areas we address in every multiplex drawing package:
- Fire separation: Minimum 1-hour fire resistance rating between dwelling units per OBC
- Independent egress: Each unit must have its own means of escape, including properly sized egress windows in bedrooms
- Separate services: Each unit requires independent heating, ventilation, and often separate electrical panels
- Zoning compliance: Setbacks, lot coverage, building height, and parking requirements per municipal bylaw
- Sound transmission: STC (Sound Transmission Class) ratings between units per OBC
- Accessibility: Ground-floor units may need to meet accessibility requirements depending on municipality
Related Resources
- Ontario Building Code 2024 Changes - New Multiplex Rules
- Legal Basement Apartment Permits
- Secondary Suite & Garden Suite Permits
- Building Permit Drawing Cost Guide
Frequently Asked Questions
Can I build a multiplex on a residential lot in Ontario?
Yes. Following Ontario's 2023 housing policy changes, up to four residential units are now permitted on most residential lots province-wide. This means you can convert a single-family home into a duplex, triplex, or fourplex, or build a new multiplex, subject to building code and zoning requirements.
What are the fire separation requirements for a multiplex in Ontario?
Each unit in a multiplex requires fire separation from adjacent units. The Ontario Building Code typically requires a 1-hour fire resistance rating between dwelling units in a multiplex, including walls, floors/ceilings, and any penetrations. Fire-rated doors, sealed pipe penetrations, and properly installed fire-rated assemblies are all required.