📞 (647) 494-1699Get a Free Quote
Free Quote
Rental & Investment Renovations

Duplex Conversion in Ontario

Converting a house into a legal duplex is a code project first and a renovation second. The Ontario Building Code and Fire Code set the real scope: a fire separation between units, sound-rated walls and floors, an independent means of egress from each unit, interconnected smoke and CO alarms, and ceiling heights that qualify the space as living area. Ontario's gentle-density rules now permit additional units on most residential lots as-of-right, so zoning is rarely the obstacle it once was — the work is in executing the separations properly and registering the unit with your municipality.

We build duplex conversions in the order that protects your budget: feasibility before drawings, drawings before permits, permits before demolition. Feasibility checks the items that kill projects — basement height, window sizes for bedroom egress, parking rules, and the electrical service's capacity for a second panel. From there, permit drawings by a qualified designer go to the building department, and construction proceeds through staged inspections. Fire separations use rated drywall assemblies, penetrations get fire-stopped, and floor assemblies are built to the sound ratings the code demands so the two households genuinely do not hear each other.

What this covers

  • Feasibility review: ceiling heights, egress windows, parking, zoning and servicing
  • Permit drawings by a qualified designer and the full municipal application
  • Fire-rated separation walls and ceilings between the two units
  • Sound-rated (STC-compliant) wall and floor assemblies with resilient channel
  • Independent entrances and code-compliant egress from each unit, including window wells where needed
  • Second kitchen and bathroom with licensed plumbing and electrical rough-ins
  • Interconnected smoke and CO alarms across both units
  • Separate electrical panels or sub-metering and HVAC zoning where services split
  • Municipal two-unit registration and final inspections

What affects the price

  • Basement ceiling height and how much underpinning or lowering, if any, the second unit needs
  • Egress — whether existing windows and doors qualify or new openings and wells must be cut
  • Electrical service size, since many older homes need an upgraded service to carry two units
  • How much of the existing structure already provides fire separation versus needing full rebuild
  • Separate services: individual heating, metering and laundry add cost but raise rentability
  • Municipal requirements, which vary in parking, registration and inspection detail

Every home is different, so we don’t publish flat prices — the quote is free and based on your actual job.

Duplex Conversion near you

We take quote requests across Ontario. Local pages:

TorontoOttawaMississaugaBramptonCaledonHamiltonVaughanMarkhamRichmond HillAuroraNewmarketGeorginaWhitchurch-StouffvilleKingOakvilleBurlingtonMiltonHalton HillsOshawaWhitbyAjaxPickeringClaringtonKitchenerWaterlooCambridgeLondonBarrieInnisfilBradford West GwillimburyCollingwoodSt. CatharinesNiagara FallsWellandGrimsbyFort ErieGuelphWindsorKingstonGreater SudburyPeterboroughThunder BayBrantfordBellevilleSarniaWoodstockStratfordOrangevilleCornwallNorth BaySault Ste. MarieChatham-KentOrilliaWasaga BeachMidlandNew TecumsethSt. ThomasKawartha LakesCobourgPort HopePrince Edward CountyQuinte WestLeamingtonOwen SoundBracebridgeHuntsvilleNiagara-on-the-LakeTimminsBrockville

Common questions

Is my house eligible to become a duplex?
Under Ontario's planning changes, most residential lots may now add units as-of-right, so the question is usually physical rather than zoning-based: ceiling height in the proposed unit, window sizes for bedroom egress, a workable second entrance and adequate servicing. We run a feasibility review against your municipality's specific requirements before you spend anything on drawings.
What does a fire separation between units actually involve?
A continuous rated assembly — typically specific drywall layers on framing — between the two dwellings, including the ceiling between floors, with every duct, pipe and wiring penetration fire-stopped. Doors in the separation must be rated and self-closing. It is inspected work, and it is the single most important element distinguishing a legal duplex from a house with a second kitchen.
Why do the sound ratings matter if fire separation is already required?
Because the Building Code requires both, and because sound is what tenants complain about. Assemblies between units must meet a minimum sound transmission class, which we achieve with resilient channel, insulation in the cavity and properly detailed drywall layers. Building it into the fire separation at the same time costs far less than retrofitting after a tenant dispute.
Do I have to register the second unit with the city?
Most Ontario municipalities require two-unit houses to be registered or licensed after passing final inspections, and lenders and insurers increasingly ask for proof. Registration is what makes the unit legal to advertise and rent. We carry the project through its final building and fire inspections and hand you the registration paperwork completed.

Ready to sort out your duplex conversion?

Tell us what you're planning — one room or the whole home — and get a free quote.

Get a Free QuoteWhatsApp usCall (647) 494-1699