Verchères is a historic municipality on the South Shore, crossed by the St. Lawrence River and surrounded by agricultural areas that offer bats an exceptional hunting ground. It is in this context that the owners of an ancestral home contacted our team after noticing bats flying away every evening from the east cornice of their residence. Built in the mid-twentieth century with traditional materials and techniques, this house had several weak points typical of old buildings: cracked mortar, aged cedar shingles and wood soffits in poor condition. Our team in Verchères is well aware of the particular challenges posed by this type of built heritage, including the fragility of the materials and the need to preserve the historic appearance of the facades while ensuring effective and sustainable exclusion.
Characteristics of the heritage inspection
The inspection of an ancestral home requires special attention and a constant concern not to damage the materials in place. Our technician conducted a comprehensive visual inspection using an endoscopic inspection camera to examine hard-to-reach cavities without drilling or disassembly. Several distinct areas of activity have been identified: one under the east cornice, the other in the space between the panelling and the original kraft paper windscreen. The distribution of guano deposits on the attic floor has made it possible to trace the main area of activity of the colony, estimated at about fifty individuals according to twilight observations. The bat capture techniques implemented have been carefully adapted to minimize interventions on the heritage structure while guaranteeing the effectiveness of the exclusion process.
Analysis of active entrances revealed that bats primarily used the spaces between the wooden planks of the ledge, where the wood had shrunk over time. These openings, only a few millimetres long, are more than enough for the little brown bat to enter the cavities of the building. Our technician also noted the probable presence of the Great Brown Myotis, a slightly larger species whose silhouette in flight had been described by the owners during their evening observations. The diversity of the species potentially present has led to the choice of exclusion devices towards models with a sufficiently wide opening to accommodate both formats.
Respectful exclusion of heritage
The exclusion method has been carefully adapted to leave no visible marks on the historic façade once the work is completed. Flexible fabric exclusion devices were preferred to rigid plastic solutions, as they integrate better with the irregular surfaces of old wood without creating mechanical stresses on fragile materials. These devices were installed in the evening after the bats had left for the hunt, and checked each morning the following morning. All secondary accesses were sealed with fine steel wool, which is virtually invisible once inserted into the cracks. The caulking work at the entry points was carried out with finishing products carefully matched to the existing colours, to fully respect the original appearance of the heritage residence.
Our team carried out night observations on the first three nights to ensure that the exclusion devices were working properly. It is essential to check that bats do not try to force new openings when their usual exits are modified. No such disturbance was observed, and the colony gradually left the area within a week.
Final sealing and preservation of the building
After confirmation that all the bats had left, the exclusion devices were carefully removed and the openings closed permanently. The wooden cornice joints were carefully caulked, and the boards with too large cracks were replaced identically with wood of the same species and profile. The attic was completely decontaminated including vacuuming up accumulated guano, replacing soiled insulation, and enzymatic disinfecting of exposed surfaces. Our extermination services in Quebec systematically incorporate a long-term vision to ensure that the solutions put in place withstand the years and the rigors of the Quebec climate. The owners of the ancestral home in Verchères benefited from a detailed report with a personalized maintenance logbook, documenting the areas to be monitored as a priority each spring to prevent any new colonization and preserve their family heritage in impeccable condition for future generations.