What is the cost of repairing a flooded basement?

A flooded and water-damaged basement can be a costly repair for homeowners without insurance. Having a comprehensive policy is a wise decision that can prevent you from risks of being stranded with a steep restoration bill.

How much do water-damaged basement renovations cost?

According to ServiceMaster Restore Vice President David Mercer, the average price in Canada for restoring a flooded basement is between $12,000–$18,000, which includes clean-up and reconstruction. Costs can escalate depending on the quality of material in your basement and how much of your property is damaged. Insurers usually cover possession loss, provided the cause of loss isn’t excluded and the value falls within limits defined in your policy. 

Repair costs can be broken down into:

• Clean up: Typically, the cost to clean up the basement is 30–50% of the total cost, anywhere from $4,000–$10,000 on average.
• Reconstruction: Makes up the rest of total repair cost; varies between $10,000–$15,000.
• Wastewater clean up: Repair costs could double if your basement is flooded by wastewater due to additional cleaning, sanitization, and safety precautions.
• Mitigation: Costs can also escalate if there is a high volume of water, especially during heavy rain flooding events, which could raise mitigation costs up to $10,000–$15,000. Repair work would cost an additional $15,000–$20,000.
• Long-term infrastructure cost: Replacement or new installation of sump pumps, backwater valves, or exterior and interior waterproofing are additions to the amount you would need to secure your basement from repeat flooding in future.

“I wouldn't want someone to walk away from this article thinking the average loss is $18,000. ‘If I have $20,000 of coverage on my policy, I'm going to be safe,’” Mercer said. “That's not the case at all.”

How basements can flood

Water can get into your basement three different ways, Mercer says, which include:

• A rupture in the water supply line to your home or a pipe burst
• A break in your waste outlet that gets water out
• External water into the home either through a window, walls, or foundation 

Read more: Install weeping tiles for your home to avoid a flood of tears

Seepage could occur from a power outage that turns off your sump pump, a sewer line backup, aging infrastructure, or improper external grading after landscaping changes.

Mercer told Rates.ca that any of those scenarios could happen any given day, with water coming in from the outside more often during the spring when there is a thaw and storms. Water damage can vary from up to eight feet of water in the basement to small pools or pinhole leaks. The cause of the most significant damage to basements is sewer line backups because you not only have water entering your home, but often contaminated water. 

“That can become more costly to address because there’s more safety concerns that need to take place and more cleaning that’s required,” Mercer says.

Learn more: How backwater valves protect against sewer backup

What to do if your basement is flooded

Mercer recommends calling a restoration specialist first if you discover basement flooding, as time is of the essence to avoid further damage. “The longer [water] sits, the more opportunity there is for things to get worse,” he says. A restoration professional will stabilize your property and make sure no further damage is done.

If you see your basement flooded, you should act quickly. Mercer recommends the following:

• Avoid further damage: Get the area and contents as dry as possible. 
• Safety comes first. A lot of water in your basement could pose potential risk of electrocution. It is important to be aware of the risks and be careful not to slip and fall. 
• Call a restoration professional: If there are concerns about safety, call a restoration professional to conduct an assessment before you can safely enter your basement. 
• Clean up: Homeowners can clean up the water themselves, but often there will be moisture trapped in material that will start to smell after a few days. A professional is better equipped to clean those hard-to-get-to places and helping with mold remediation. Excess water accumulation can accelerate mold spreading to framing or insulation.  
• Call your insurance company: While restoration professionals are on their way, homeowners should contact their insurance provider to understand nuances of their policy and what is covered. Take photos, assess, and record damage.

Helpful guide: Will my home insurance cover a burst pipe?

It is often not necessary that you get multiple quotes for basement restoration, as insurance companies tend to vet contractors and already know the price structure in place. Mercer says the industry is fairly standardized in pricing. Typically, homeowners would want to get a flooded basement addressed as soon as possible and not spend too long shopping around before work begins.

What insurance can cover if your basement floods

In some instances, insurers may not cover a sewer line backup. Other carriers may have a reimbursement limit, such as amounts up to $10,000 baked in the policy, according to Mercer. When Montreal was flooded in 2024 and southern Ontario, including Windsor, was under water in 2023, some homeowners faced limits on their policies. Mercer says those areas were prone to flooding and insurance companies mitigated risk by having payout limits on policies. 

Learn more: Get Flood Insurance quotes in Canada

You can buy additional insurance to get more coverage. But usually, homeowners look for the minimum they need to get them through when initially buying home insurance.

It’s not that common for there to be gaps in insurance policies, Mercer says, which are typically based on the situation and region. Still, it is something insurance holders should be aware of and discuss with their broker when purchasing their policy or renewing it.

“[It’s] a really important piece for consumers in the insurance market to understand the limits, exclusions, and deductibles in their policy,” he says.