The manager of a six-unit rental building in Saint-Charles-sur-Richelieu, in the Montérégie region, asked us to intervene after several tenants reported nocturnal noises in the walls and rodent tracks in the mechanical room in the basement. Saint-Charles-sur-Richelieu, a municipality in the Richelieu Valley located between Saint-Marc and Saint-Denis, is a historic and agricultural area along the river, where old residential buildings stand alongside local businesses. This type of environment is particularly conducive to the establishment of rat colonies, which take advantage of common garbage bins, collection outlets and uncrowded basements. Managing an infestation in an occupied multi-unit building requires rigorous coordination and transparent communication with residents to complete treatment without disrupting their daily lives.
Diagnosis in a multi-unit building
The initial inspection covered the entire building: basement, partial crawl space, common laundry room, waste room, upstairs corridors and outdoor perimeter. Technicians identified characteristic greasy flows along the walls of the electricity meter room and in a technical duct connecting the basement to the first floor. The presence of fresh droppings and food caches, consisting of remains transported from the garbage room, confirmed an active colony of Norway rats. The main access point was an opening of several centimetres around a heating pipe entering through the foundation on the north side of the building, aggravated by the erasure of the exterior plaster over an area of about fifty square centimetres. Our rodent infestation inspection also highlighted traces in the vertical technical sheath, indicating that the animals had been moving between floors for some time. Interviews with tenants completed the picture, confirming that the noises had been heard for several weeks in various units.
Treatment protocol adapted to occupied buildings
Faced with the complexity of an inhabited building, the treatment was planned in close consultation with the manager. Padlocked bait stations have been installed in all common areas inaccessible to residents: mechanical room, waste room, outdoor perimeter under the fire escapes and along the foundation. The first and second generation rodenticide baits were placed in cases that were certified to meet provincial regulations, child and pet resistant. High-capacity mechanical traps were placed in the accessible engineered conduits and in the corners of the basement, where the flows were most pronounced. Three follow-up visits over two weeks allowed the activity to be gradually reduced until it was completely extinguished. All our methods for rental properties are described on the page of our rat extermination service. Rodent decontamination was then carried out in the mechanical room: removal of nests and faeces, disinfection of surfaces with a biocidal product effective against pathogens associated with rodents.
Sealing and recommendations for rental management
After the treatment phase, our team proceeded to seal all the identified openings. The foundation crack was filled with rodent-resistant hydraulic mortar, pipe penetrations were sealed with steel wool and durable sealant, and fine-mesh metal grates were installed on the basement’s low air intakes. The manager received a written intervention report detailing the work carried out and the monitoring points to be included in its semi-annual inspections. Specific recommendations have been made for the management of common waste: closed bins with latches, more frequent collection in summer and regular cleaning of the rubbish room with hot water and disinfectant. Consult our realization on rats in an urban building on the South Shore and our case study on mice in an apartment building for other examples of intervention in a rental environment. The team at our extermination company also offers a regular follow-up program for managers who wish to proactively protect their buildings throughout the year.