Every residential rental contract, whether it's a lease or a month-to-month rental contract, contains an implied warranty of habitability. In other words, even if not included in the contract, you, the landlord, are obligated to your residents to provide living space that's fit for human occupancy and complies with state and local building, health, and safety codes that materially (significantly) affect a tenant's health and safety.
Although residents are responsible for some repairs, especially if they break something, you're responsible for repairing any problems that make the rental unit uninhabitable — unfit to live in. The implied warranty of habitability obligates you, as landlord, to provide the following:
Windows and doors in working condition
Floors, stairways, and railings in good repair
Effective weather protection and waterproofing of roof and exterior walls
Plumbing in good working order, including running water, a sufficient amount of hot water, and sewage disposal
Electrical system in good working order, including wiring, outlets, lighting, and equipment
Gas in good working order, if applicable
Heating, in areas where heating is required
Clean and sanitary buildings, grounds, and other areas
Adequate trash receptacles
At least one working toilet, sink, and bathtub or shower — bathtub or shower must allow privacy and be ventilated
A kitchen with a sink made of non-absorbent material (not wood, for example)
Emergency fire exits
Deadbolt lock and peephole on entry door(s) to unit
Working smoke detectors
Locking mailbox
Ground fault circuit interrupters for outlets near water, such as in bathroom and kitchen and near pool and sauna
Establish a maintenance and repair policy and system for responding quickly to resident requests for maintenance. Respond as quickly as possible to requests for repairs to problems that make a unit uninhabitable, such as a broken furnace on a very cold day, a smoke detector that doesn't work, or a sink that's backing up.
