Who fixes water damage and mold in an Ontario rental, the landlord or the tenant?

Who has to repair a rental unit in Ontario?

The landlord. The Residential Tenancies Act, 2006 says: 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. (Residential Tenancies Act, s. 20(1)) The next subsection closes a common excuse: 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. (Residential Tenancies Act, s. 20(2)) In plain words, a leak that was already there on move-in day is still the landlord's to repair.

What is the tenant responsible for?

Two things, both narrow. On cleaning: The tenant is responsible for ordinary cleanliness of the rental unit, except to the extent that the tenancy agreement requires the landlord to clean it. (Residential Tenancies Act, s. 33) On damage: The tenant is responsible for the repair of undue damage to the rental unit or residential complex caused by the wilful or negligent conduct of the tenant, another occupant of the rental unit or a person permitted in the residential complex by the tenant. (Residential Tenancies Act, s. 34)

The Act does not use the word mold. Mold that comes from a leak or from damp in the building is a state-of-repair question, so the landlord's duty in section 20 is the one that applies. That is a plain reading of the Act, not a ruling. If a tenant did cause the damage, the landlord may apply to the Board for an order requiring the tenant to pay reasonable costs that the landlord has incurred or will incur for the repair of or, where repairing is not reasonable, the replacement of damaged property. (Residential Tenancies Act, s. 89(1))

What can a tenant do if the landlord does not repair?

The tenant can ask the Landlord and Tenant Board for An order determining that the landlord has breached an obligation under subsection 20 (1) or section 161. (Residential Tenancies Act, s. 29(1)) The Board may then Order the landlord to do specified repairs or replacements or other work within a specified time. (Residential Tenancies Act, s. 30(1)) There is a time limit: No application may be made under subsection (1) more than one year after the day the alleged conduct giving rise to the application occurred. (Residential Tenancies Act, s. 29(2)) For an owner, the lesson is to repair quickly and keep dated records of what was done.

What should an owner do right after a leak?

These steps come from Health Canada. Its mold guide says it is intended for the general public, including property owners, landlords and tenants. (Health Canada, Guide to addressing moisture and mould indoors) Health Canada spells it mould.

1. Power first. Shut the power off to the flooded area at the breaker box. (Health Canada, Flood cleanup: keep in mind indoor air quality)
2. Know the water. Determine if the flood involves relatively clean water or sewage-contaminated water. (Health Canada, Flood cleanup) A professional is needed when The water involved in floods or significant leaks was contaminated with sewage, or chemical or biological pollutants. (Health Canada, Guide to addressing moisture and mould indoors)
3. Fix the source and dry fast. Immediate action is important. Your house and furnishings are less likely to grow mould if they are dried within 48 hours. (Health Canada, Flood cleanup) Also: Unless the cause of the moisture problem has been identified and solved, mould will reappear. (Health Canada, Guide to addressing moisture and mould indoors)
4. Take out what cannot dry. Dispose of all insulation materials, drywall, carpets, particleboard furniture, mattresses, box springs, stuffed toys, pillows, cushions and furniture coverings that have been exposed to flood water and cannot be dried. (Health Canada, Flood cleanup)
5. Do not paint over it. Painting over a mouldy surface does not kill mould and does not stop it from growing back. And: Do not use bleach to clean up mould. (Health Canada, Guide to addressing moisture and mould indoors)
6. Know when to call a professional. Health Canada recommends that a qualified professional assess and clean up large areas of mould. Its list of situations that need one includes Mould that returns following cleaning, indicating that the source of moisture has not been addressed and There is suspected hidden mould contamination inside walls or above ceilings. (Health Canada, Guide to addressing moisture and mould indoors)

Can the landlord go in to repair without notice?

Only in an emergency. The Act says: A landlord may enter a rental unit at any time without written notice, in cases of emergency. (Residential Tenancies Act, s. 26(1)) Otherwise a repair needs written notice at least 24 hours ahead. The details are in our guide on entering a rental unit for repairs.

What does it mean for my job?

After a leak the work is repair: wet drywall out, new drywall hung and finished, paint, new floors, and the pipe fixed. Reborn Renos does all of it. Michal is a plumber, so a leaking pipe is part of the same job as the wall it soaked. Water damage repairs and mold remediation are larger projects, quoted separately, and a bigger job gets its own written quote with every line priced. See water damage repair for rentals, and income property maintenance for the small on-call jobs. The walls and floors are on walls, framing and drywall and flooring. Some repairs also need a permit: see permits for rental renovations.

We work in Beamsville, Lincoln, Grimsby, Stoney Creek, Hamilton, St. Catharines, Thorold and Niagara Falls. Call (905) 920-1418, Monday to Saturday, 7 am to 7 pm, or use the request page with photos of the damage.

This is a plain summary, not legal advice. The linked law is what counts.

Published by Reborn Renos, Beamsville. Updated November 1, 2026. Free to share and quote, with a link back to this page.