Mice in a Boston Rental: Who Has to Deal With Them

If you rent in Boston and hear the first scratching in a wall this fall, the question is whose problem it is. The state sanitary code answers that by the size of the building.

One unit: the occupant, with an exception

Under 105 CMR 410.550(A), in a residence containing one dwelling unit, the occupant maintains the unit free from all pest infestation and is responsible for pest elimination. The exception is structural: the owner is responsible for pest elimination if they haven’t maintained the structural or other building elements necessary to keep pests from entering. A rotted sill or an open gap around a pipe is the owner’s problem even in a single family rental.

Two units or more: the owner

Under 105 CMR 410.550(B), the owner of a residence containing two or more dwelling units, including a rooming house, maintains it and its premises free from infestation and is responsible for pest elimination. A two-family or a three-decker counts. Two more duties sit with the owner under (F) and (G): an inspection of each unit for pests before a new occupancy, and documented results and actions kept available to the board of health on request. Occupants in any building, under (E), keep their unit in a sanitary manner so it doesn’t attract pests.

What extermination means in the code

Section (C) defines it. Extermination is accomplished by eliminating the harborage places of insects and rodents, removing or making inaccessible materials that may serve as food or breeding ground, poisoning, spraying, fumigating or trapping, or any other recognized and legal pest elimination method. Removing what pests eat and where they hide is on that list alongside traps and poison.

The 48-hour notice

When a company applies pesticide indoors, section (D) requires pesticide applicators or their employers to give at least 48 hours pre-notification, in writing, to occupants of all residential units. The notice has to carry the company’s name and phone number, the proposed date, the locations to be treated, and the names, EPA registration numbers and active ingredients of the products that may be used. Owners and occupants then provide access to common areas and units and follow the applicator’s preparation instructions.

Outside the building: 311

The City of Boston’s Rodent Action Plan asks residents who spot signs of rodent activity to report it to 311 and says its teams will be on-site within 24 to 48 hours. The Inspectional Services pest management program describes its work as inspections, trapping and baiting in parks, playgrounds and public ways. The plan’s own summary of the root cause is that trash is the number one food source for rats. Boston also hosts the second annual National Urban Rat Summit on Sept 23 to 24, 2026.

If it’s happening in your unit

Write to the owner or manager with the date, the room and what you saw, and keep a copy. In a building of two or more units, elimination is their job under the code. In a single family rental, look at how the pests are getting in before you assume it’s yours. Renting or owning in Greater Boston and not sure whose call it is? Send me the building and I’ll walk you through it. Diana Kim, REALTOR®, eXp Realty.