The only sure way to determine whether or not the Residential Tenancies Act applies, in whole or in part, is to file an application under Section 9 of the Act. To do this, landlords can file an A1 application with the Landlord and Tenant Board, the forms and instructions are available here –https://tribunalsontario.ca/ltb/forms/
Situations that are completely exempt from the Act are listed in Section 5 of the Act. Partial Exemptions are listed under Sections 6, 7 and 8 of the Act, which you can read at the following link: https://www.ontario.ca/laws/statute/06r17#BK5