Why waterproofing should be top of mind when looking to buy a house

By: Sandra MacGregor on December 9, 2025

Quick takeaway:

Waterproofing is essential for protecting your home from water damage, which is now the leading cause of property insurance claims in Canada.
Without proper waterproofing, homes face risks like structural damage, costly repairs, and health hazards such as mold and mildew.
Many types of water damage, such as flooding or sewer backups, require additional insurance coverage, making proactive waterproofing a smart financial move.
Homebuyers should prioritize waterproofing during inspections, asking detailed questions about methods, materials, warranties, and documentation to avoid long-term issues.

When it comes to buying a home, it’s easy to get swept away by modern kitchens or spa-like bathrooms, but there’s one critical factor that often gets overlooked: waterproofing.

In a country where water damage is now the number one cause of property insurance claims —surpassing even fire — the challenge to keep your home dry should be a central concern for every homeowner who wants to protect their most prized asset.

Without it, you could face not only expensive repairs but also potential health hazards like mold and mildew. Plus, with many types of water damage requiring additional insurance coverage, being proactive about waterproofing can save you from financial and emotional stress down the road.

Understanding the importance of waterproofing

Few homeowners spend time thinking about the threat water poses. Yet even small leaks or seepage can lead to significant problems over time, resulting in expensive repairs and risking the safety and health of everyone under your roof.

What is waterproofing?

Waterproofing is the process of protecting a property from water infiltration, especially in vulnerable areas like basements, foundations, and below-grade structures. It involves applying specialized materials and systems to create a barrier that prevents moisture from entering and causing damage.

Without serious waterproofing, homes are exposed to risks that standard maintenance alone can't prevent or fix. Structural damage is one of the main hazards of an improperly waterproofed home. Persistent moisture can wreak havoc below the surface, gradually undermining both the safety and value of your property. When water makes its way into a structure — whether through leaky roofs, floods or foundation cracks — it weakens critical supports, rots wooden beams and warps walls and drywall.

There are different types of waterproofing methods depending, depending on the property's specific needs.

Exterior waterproofing: involves excavating around foundation walls to apply a waterproof membrane. Stops water before it reaches the foundation. Effective but costly and disruptive.
Interior waterproofing: manages water inside the basement using systems like French drains (weeping tiles) and sump pumps. Sealants may help but are temporary fixes.
Drainage systems: redirects water away from the foundation using clear gutters, downspouts, and proper yard grading.

Why you should waterproof your home

When it comes time to buy home insurance, fire is often top of mind for most people, according to Steven Harris, licensed insurance broker and LowestRates.ca expert.

“But, with climate change and increased storms, water damage is a much more frequent occurrence and can be incredibly severe,” he says. “It’s vital for homeowners to take water damage seriously.”

Being able to avoid costly repairs is another major reason homeowners need to be informed about the value of a waterproofed home.

“If you have a finished basement and suffer a sewage backup, cleanup alone might be upwards of $15,000 to $20,000 before you even start actual repairs or consider the cost of replacing damaged contents,” says Harris.

Lastly, and most importantly, improper waterproofing can lead to serious health concerns in a few different ways. Water can reach electrical systems, increasing the risk of fire or electrocution. Mold and mildew can thrive in damp environments and can negatively impact health.

Questions every homebuyer should ask

Waterproofing is often an area where contractors may cut corners to lower costs, often with disastrous long-term consequences for the homeowner. These shortcuts can lead to premature failure of the waterproofing system, resulting in leaks, mould growth, and costly structural damage that may not become apparent for several years.

To avoid these risks, make sure you do a thorough and professional home inspection, and ask these questions when buying a home, especially a new build or recently renovated one:

What waterproofing method was used? Ask for details on whether it was an interior or exterior system.
What materials were used? Inquire about the type of waterproof membrane or coating applied. Reputable contractors use high-quality, durable materials designed for long-term performance.
Is there a warranty? A professional waterproofing job should come with a transferable warranty. Ask for the warranty documents, understand what is covered (materials and labour), and for how long.
Who did the work? Get the name of the company that performed the installation. This allows you to research their reputation and credentials.
Can I see documentation? Request any permits, inspection reports, or invoices related to the waterproofing work.

Is flooding covered by home insurance in Canada?

Many Canadians are surprised to learn that most home insurance policies do not cover all forms of water damage. Basic coverage usually includes sudden and accidental events, like a burst pipe or a leak from a water heater — “if you had that type of a loss, that would generally be covered or included in a basic homeowner's policy,” says Harris.

However, damage from groundwater, sewer backup, or overland flooding requires additional endorsements. These are not part of standard coverage and must be added.

“You get into what are called extended water coverages or optional water coverages,” he says. Understanding how water enters your home is key to knowing if the damage is covered.

Types of available water coverage endorsements for your home

Here are some water coverages that may be added to your policy, depending on your home. Coverage and deductibles vary by provider.

Groundwater coverage: Protects against damage from cracks in your basement foundation, especially risky for finished basements. Reduce risk with professional waterproofing of foundation walls and floors.
Sewer backup coverage: Covers damage from sewer backups caused by heavy rain or old plumbing. Prevent damage with sump pumps, backwater valves, and water sensors.
Overland flooding coverage: Covers flooding from rivers, streams, heavy rain, or snowmelt entering your home. Prevent with sloped landscaping, cleared eavestroughs, and downspouts directed away from the foundation.
Surface flooding coverage: Covers rapid water accumulation from heavy rain or snowmelt. Mitigation strategies are similar to overland flooding.
Inland flooding coverage: Often combines overland and surface flooding into one add-on called ‘inland water coverage.’

How to make sure you’re properly covered for flooding

Start by reviewing your home insurance policy carefully, focusing on water damage protections and exclusions. Don’t assume you’re covered — understand the specifics.

Harris emphasizes the importance of clarity: “I think the average consumer hearing terms like ‘groundwater’ versus ‘overland coverage’ versus ‘surface water’ doesn’t know which one to choose,” he says. “It can be very overwhelming. Educating yourself and asking lots of questions is important.”

Policy limits and deductibles can change yearly based on your insurer’s losses, Harris notes. Review the fine print annually to ensure your coverage hasn’t changed, even if you’ve stayed with the same provider.

“If you need help reading your insurance documents, don’t be afraid to call. That’s what a licensed broker is there to do; to assist you if you need help to fully understand your insurance coverage and make sure you are protected.”

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