What repair and maintenance obligations does a commercial tenant have under an Ontario lease?

There's no standard, protective default allocation of repair obligations the way there is under residential tenancies law — in a commercial lease, repair and maintenance responsibilities are whatever the lease says they are, and this is an area where negotiated wording matters enormously. A typical structure has the tenant responsible for interior, non-structural repairs and maintenance, including its own fixtures, interior finishes, and equipment, while the landlord retains responsibility for structural elements, the roof, exterior walls, and major building systems, but many commercial leases, particularly net leases, shift considerably more onto the tenant than that.

Because there's so much variation, a tenant shouldn't assume a lease follows the "typical" structure without actually reading the repair clause closely. Some leases make the tenant responsible for a much broader range of repairs, or require the tenant to maintain equipment like HVAC systems serving the unit, which can be a significant and unexpected cost if not budgeted for.

Before signing, review exactly what repair and maintenance obligations you're taking on, get a sense of the condition of anything you'll be responsible for maintaining, and negotiate limits where the allocation feels disproportionate to what you're actually getting in the space.