In plain English
The landlord must keep the rental unit and building in a good state of repair, fit for habitation, and compliant with health, safety and maintenance standards — even if the tenant knew about the problem before moving in.
The statute text
20 (1) A landlord is responsible for providing and maintaining a residential complex, including the rental units in it, in a good state of repair and fit for habitation and for complying with health, safety, housing and maintenance standards.
(2) Subsection (1) applies even if the tenant was aware of a state of non-repair or a contravention of a standard before entering into the tenancy agreement.
View this section on the official Ontario e-Laws site →
Reproduced under the King’s Printer for Ontario / Open Government Licence – Ontario. Confirm against the official e-Laws consolidation before relying on it.