Usually not — Ontario's HCRA licenses builders of new homes, and its own guidance says a typical renovation or upgrade to an existing home doesn't make the home “new” and doesn't trigger the licensing requirement.
Short answer
Usually not. HCRA's own guidance says renovations or upgrades to an existing home typically don't make the home “new” and so don't require a builder licence. But HCRA sets no bright-line test for how substantial a renovation has to be before it crosses that line — a major rebuild is a case-by-case call, not a percentage.
Ontario's Home Construction Regulatory Authority is direct about this: “Typically, renovations or upgrades to an existing home do not make the home ‘new’ — and as such, do not require the builder to be licensed”. Licensing under the Ontario New Home Warranties Plan Act turns on whether what's being built counts as a “home” that hasn't been previously occupied — an existing house getting a new kitchen or a bathroom addition doesn't cross that line. See the builder licence requirement in full.
HCRA's own advisory on the definition doesn't give a bright-line test — no percentage, no square-footage threshold: “To be a ‘new’ home, the dwelling that is being built must be more than just a renovation to an existing building”, and beyond that, HCRA directs a project that incorporates pre-existing elements toward its registrars for a case-by-case call. A gut renovation, a major addition that roughly doubles the footprint, or converting a property into a condominium are exactly the projects where “is this still a renovation” stops being obvious — and HCRA doesn't publish a number that settles it.
A kitchen remodel, a basement finish, or an addition that leaves the original structure standing — no builder licence needed. A full teardown-and-rebuild on the same lot, or anything a reasonable person would call a new house, almost certainly does. If a project sits in between, confirm it with HCRA's registrars before signing anything that assumes one answer or the other. If you're on the buying side of a project that does need a licence, verifying the vendor's HCRA registration before signing a purchase agreement is the same five-minute check worth doing regardless of project size.
A short call is enough to flag a renovation that's actually crossed into new-home territory.
