A twelve-apartment rental building located in Calixa-Lavallée, a small rural municipality in the Montérégie region neighbouring Verchères and Contrecœur, was the scene of a persistent infestation of field mice that had been disturbing several tenants since the beginning of the fall. Bordered by a wooded area typical of this peaceful and mostly agricultural environment, the building offered many access routes for rodents: poorly sealed expansion joints, ventilation duct passages and space under the exterior wooden stairs. The residents’ complaints mainly concerned nighttime noises in the ceilings of the ground floor and the presence of droppings in the kitchen cabinets of two apartments in the basement. Our company was contacted by the building manager to put an end to the situation.
Diagnosis in a multi-unit setting
Inspecting a multi-residential building requires a structured approach. The technician mandated by our team in Calixa-Lavallée began by inspecting the common areas, the technical rooms and the exterior perimeter before visiting the units concerned. The corridors in which the field mice moved through the walls were identified by the presence of traces of friction (greasy stains on surfaces) and urine tracks visible under ultraviolet light. A total of five entry points were identified, two of which were particularly important at the junction between the exterior cladding and the concrete base.
The manager provided access to all units, which allowed for a comprehensive assessment. Fresh droppings were found in three separate apartments, confirming that field mice were actively moving through the partitions and suspended ceilings. This mobility within a large building complicates the treatment and justifies a coordinated strategy across the entire structure.
Coordinated treatment throughout the building
The response plan was structured in two phases. The first phase, known as population reduction, consisted of installing pressure traps in each space inaccessible to tenants: false ceilings, electrical rooms, basement and mechanical room. Secure baiting stations have been positioned outdoors along the foundations and in the crates set up for this purpose for residential buildings. This approach is consistent with provincial regulatory requirements for the use of rodenticides in living spaces.
The second phase focused on caulking and exclusion. All identified entry points were addressed: application of compacted steel wool in the gaps, mortar sealing for foundation cracks, and replacement of defective perimeter joints around plumbing ducts. For apartment buildings, this step is often more complex than for a single-family house due to the number of penetrations into the walls and the interfaces between the different building materials. Our technicians are trained to intervene effectively in these contexts, as evidenced by our work on a similar building recently treated. For a complete view of our services, visit the page dedicated to field mouse extermination on our website.
Decontamination and advice to tenants
Once the field mice activity was confirmed as over after two follow-up visits without capture, a rodent decontamination operation was carried out in the common areas and affected dwellings. This step includes removing nests and contaminated materials, disinfecting surfaces and, if necessary, applying an odour neutralizer to prevent other rodents from attracting chemical traces left by the colony. Tenants were informed of good practices to adopt in order not to recreate conditions favourable to field mice, in particular the rigorous management of food waste and the hermetic sealing of containers in pantries. The entire process, from the initial inspection to the final decontamination, demonstrates the integrated approach that Nova Extermination implements to protect residential buildings in the Montérégie.
Pest management in a rental building also involves communication with residents. Our team took the time to explain to each tenant concerned the steps of the treatment, the precautions to be taken and the signs of a possible reactivation. This transparency helps to maintain trust between the manager and its tenants throughout the process. A well-managed building in terms of pests retains its rental value and avoids conflicts related to habitability conditions, two direct advantages for the owner. Calixa-Lavallée and the neighbouring areas of Verchères and Contrecœur are areas where annual vigilance is strongly recommended for buildings located on the edge of green spaces.