Basement Renovations in Markham

York Region

Basement Planning in Markham

Markham's mix of established and newer subdivisions makes for one of the most diverse renovation markets in York Region.

Unionville and Thornhill carry much of Markham's older, established character, while newer growth in areas like Cornell continues the town's expansion further east.

What Markham Says About Second Units

Every municipality writes its own rulebook for basement apartments, and Markham is no exception. It is not exciting reading, but it is far cheaper than finding out the hard way. Here is what the City of Markham published on its own page when Reno Rise reviewed it (September 2026).

• Two-unit houses must be registered under Markham’s Occupancy Registration of Two-Unit Residential By-law 2018-57, and the City warns that occupying an unregistered two-unit house can lead to court action.
• Markham Fire & Emergency Services inspects both units as part of registration.
• New second suites need a building permit from Building Standards. Suites created before July 1, 1993 use a declaration form and are assessed under the Fire Code’s retrofit provisions for older units.

Read the source before you plan: City of Markham: additional or second unit information. Rules, fees and program deadlines change, so confirm with the municipality. Markham is outside the City of Toronto, so Toronto Building’s rules do not apply; the legal secondary suite guide explains the general considerations.

Whatever the age of the house, the plan starts the same way: measure the ceiling height, look for signs of moisture, and decide whether you want a finished basement or a self-contained suite. Get those answers early and the rest of the project gets calmer. See basement renovation planning, underpinning, waterproofing and egress windows for the most common issues.