Ensure the resilience of buildings

Like most cities in the world, Montréal faces unusually intense rainstorms that can generate rapid rainwater accumulations on roads and risk flooding homes or causing sewer backups.  

Homeowners are strongly advised to identify potential vulnerabilities in their home to make sure it is adequately protected. The most effective measure to avoid the impacts of heavy rains is to ensure the resilience of buildings and prevent water from seeping in. The community is central to this strategy and to the actions that must be taken to increase the resilience of private buildings.

Checklist 

All building types 

• Check your home for entry points that may facilitate water surging in from the street, such as a downstairs entrance. 

• Make sure you have properly working check valves (also known as backwater valves or backflow preventers) on plumbing fixtures located below street level. It is essential that there is a check valve for all drains on the floor or for plumbing equipment (for example: toilets, taps, etc.) 

• If possible, clear debris that could block the entry of water from the sump on the street near your residence in order to facilitate the collection of surface runoff. 

• In the basement, make sure floor drains are clear and valuables are in watertight containers.  

• Make sure that the openings in the building are watertight. For doors and windows located under or at street level, there are a number of permanent or temporary protection measures on the market that help reduce the risk of being flooded, such as watertight partitions and doors, removable cofferdams, etc. 

Homes with sloped roofs  

• Gutters must send water to a permeable surface and must not be connected to the foundation drain.  

Plex buildings 

It’s possible that there may only be one indoor pipe that routes both domestic water and rainwater from the flat roof. This type of pipe presents a risk of water overflowing from plumbing fixtures upstairs during a severe thunderstorm.  

It is recommended that you separate the rainline from the flat roof as indicated in this RBQ guide (in French).  

Vulnerability map  

You can view the Montréal agglomeration climate risk vulnerability map (in French) l  and select the “Identification des cuvettes 2021” (2021 Basin Identification) map. This map identifies areas whose naturally sunken topography has the potential for surface water accumulation during heavy rains. 

Tangible actions for a safer future 

Montréal has set out 10 key measures to adapt to torrential rains in its action plan for flood resilience during heavy rains.  One of the components of this plan includes support measures for owners to increase the resilience of their building. In particular, the city is committed to offering advisory services to owners on how to best protect their building against floods. 

Subsidy program 

Do you have to carry out expensive renovations to adapt your building? Montréal’s RenoPlex program offers a subsidy for certain types of renovation that help reduce the risk of flooding. Check the criteria and eligibility of your renovation project. 

Revising the RénoPlex program to make it more accessible to more homeowners is one of several measures set out in the action plan for flood resilience during heavy rains.