Following recent heavy rainfall and flooding events in Montreal throughout 2025, including the intense downpour on July 13-14 that dumped up to 100 mm of rain, as well as earlier storms in June with over 80 mm in a single day and remnants of tropical systems causing widespread damage, residents across boroughs like Saint-Leonard, Dorval, the West Island (including Dollard-des-Ormeaux and Pierrefonds-Roxboro), Côte-des-Neiges, and downtown areas are facing water intrusion in their homes.
TikTok video showing the July 2025 floods in Montreal courtesy of @vanessaazoulay
As an environmental services provider specializing in Montreal mold testing, we recommend proactive measures to address mold risks effectively.
Mold can begin to grow within 24-48 hours of moisture exposure, as spores germinate on damp surfaces under suitable conditions.
However, understanding mold’s life cycle is essential: initial growth may not immediately release detectable spores into the air, potentially leading to inconclusive early testing results.
To ensure accurate detection, it is advisable to allow the affected areas to dry thoroughly—typically 10-14 days after a flood—before testing the air for mold.
This timeframe permits any developing colonies to reach visible or measurable levels, facilitating a more reliable assessment. You see, spores may not be airborne if moisture is still saturating mold’s food source. Spores are released as a defensive and reproductive process, often when the substrate has been degraded, nutrients have been depleted, or conditions are no longer conducive to its survival. This is one of the reasons why we recommend delaying mold testing a few weeks after a flood, to ensure accuracy in results, especially if the mold may be in a different part of its life cycle.
Pre-existing mold issues can be significantly worsened by new flooding, accelerating growth, spreading contamination and even potentially harmful mycotoxins (secondary metabolites produced by certain mold species). Additionally, during the drying process, the use of fans by restoration teams may inadvertently disperse spores if mold has already begun to form, potentially increasing exposure risks. For Quebec residents, adhere to the Régie du bâtiment du Québec (RBQ) recommendations for flood cleanup, including proper decontamination of mold-affected materials.
For an unbiased evaluation, consider third-party labs like Axxonlab, which offer strictly analytical mold assessment services without providing any remediation. Their independent, lab-certified testing delivers data-driven insights, ensuring an accurate picture of contamination levels free from conflicts of interest. If you’re a tenant navigating landlord disputes, enlisting Axxonlab can be pivotal—equipping you with irrefutable evidence to bolster your case at the Tribunal administratif du logement (TAL).
After a major flood, reach out to a trusted local mold testing company for a thorough assessment, providing accurate, data-driven solutions customized to your needs.
