Protecting Homes Against Flooding

Flooding in homes is a significant concern: 20% of Canadian homes are at risk due to one or more of these failures:

• Sewer backup: Sewer systems become overwhelmed; sewage backs up into homes
• Infiltration flooding: Surface water seeps into basements through cracks in the foundation
• Overland flooding: Rainwater accumulates around houses due to poor grading or drainage

Homeowners can take several measures to protect their homes from flooding by:

• Clearing eavestroughs and downspouts of debris
• Removing debris from the nearest storm drain
• Testing sump pumps regularly
• Cleaning backwater valves
• Extending downspouts and sump discharge pipes at least 2 m from foundation
• Installing covers for window wells

Renovators can help with more complex measures by:

• Installing backwater valves
• Correcting grading to direct water 2 m away from foundation, 2% (good) to 5% (better)
• Installing sump pumps (and battery backup)
• Installing window wells (extending 10-15 cm above grade) around water-resistant windows

Homebuilders and developers can help with the following design measures:

• Proper site grading, 2% (good) to 5% (better)
• Properly sizing drainage systems (for lot and community)
• Choosing flood-damage-resistant building materials
• Raising electric service panels and appliances safely above the basement floor (ideally, they would be located on the main floor or above but at a minimum they should be raised above the basement floor as high as possible)

How do I know if flooding is a concern for my area?

New Flooding risk data means that many flood risk maps are being changed right now. Unfortunately, there are no consistent national-level flood risk maps, yet. If your region or municipality maintains a flood risk map, they can help estimate whether flooding is a concern for homes, neighbourhoods or a new development (e.g. a local map for the City of Ottawa ).

Where can I find additional resources?

Additional information can be found in this report Under One Umbrella, and in this Home Flood Protection Infographic. More detail is provided in this Handbook for Reducing Basement Flooding, or in the CSA Z800 Guideline on Basement Flood Protection and Risk Reduction