Multiplex Conversion Drawings

Duplex, Triplex & Fourplex Conversion Drawings in Ottawa

Ottawa now allows up to four dwelling units on most serviced residential lots, without a rezoning hearing. That has opened the door for homeowners and investors to convert single family homes into duplexes, triplexes, and fourplexes. Every one of these projects needs a building permit and a complete set of BCIN certified architectural drawings that meet the Ontario Building Code.

We specialize in the technical drawings that turn a multiplex idea into an approved permit.

Key Takeaways

• Ottawa allows up to four units as of right on most serviced lots, no rezoning needed.
• Every multiplex conversion needs a building permit and BCIN certified drawings.
• Each unit requires fire separation from the others under the Ontario Building Code.
• We prepare full drawing sets for duplex, triplex, and fourplex conversions.
• Good drawings speed up City review and reduce costly revisions.

What the 2026 Zoning Change Means

Ottawa Zoning By-law 2026-50 lets you put up to four dwelling units on a serviced residential lot as of right, which means no rezoning application or hearing is required. This is part of the missing middle housing shift toward triplexes, fourplexes, and small multiplexes. You still need a building permit, and that is where a complete, code compliant drawing set is essential.

What Goes Into a Multiplex Drawing Set

• Fire separation and rated assemblies between units
• Egress and life safety for every unit
• Floor plans for the existing and proposed layouts
• Site plan showing parking, entrances, and setbacks
• Elevations, sections, and construction details for permit review

Planning interior changes too? See our interior renovation drawings and basement drawings.

Frequently Asked Questions