Basement waterproofing is something that many homeowners don’t consider until they have a flooded basement, mold or a very expensive basement leak repair. Damage is often much greater at this point than anticipated.
You’ve likely begun considering basement waterproofing options when your basement walls are damp, your basement smells musty, water is leaking on the floor near the basement or you’ve even had a basement flood. However, it doesn’t take long before you come across the big question all Canadians homeowners are faced with:
Should I go with interior waterproofing or exterior waterproofing?
Both methods work. These are used daily by professionals all throughout the GTA. They all operate differently, come with different costs and are used in different scenarios. This guide provides all the information you need to make an informed decision that you can feel good about for your home.
First, Why Does Waterproofing Matter So Much in Canada?
The elements can take a toll on Canadian homes. Only in the South do you have freezing winters, snowmelt in the Spring, clay soils that retain water and cause problems with your foundation, and sudden torrential rainfalls in the Summer. All of that hydrostatic pressure, or the weight of the water against the foundation walls, in time seeps through cracks, floor joints and porous concrete.
Having a wet basement is more than just a hassle. It causes mold growth, damage to the structure, loss of home value and health issues due to the poor indoor air quality if not controlled. If you require complete basement waterproofing or just need basement leak repair, the earlier, the better.
What Is Interior Waterproofing?
Waterproofing inside does not prevent water from entering your foundation walls, it prevents water from coming into your house. Consider it to be a very high-tech catchment system that is installed within your house.
Here’s how it typically works:
A drainage way is made around the exterior of the basement floor. The bottom part of the wall is fitted with a waterproof interior membrane to guide any seeping water along the lower part of the wall to the channel. The water then flows through a sump pit, which has a sump pump that automatically releases the water away from your home. Additionally, in many instances a french drain system is interconnected to control groundwater flow under the floor slab.
Interior waterproofing is generally the right choice when:
- Your basement is already finished and excavating outside isn’t practical
- You’re working within a tighter budget
- There’s limited space around the exterior of your home (common with semi-detached and townhomes in Mississauga, Hamilton, and Cambridge)
- Water is coming in through the floor or lower wall joints rather than through foundation cracks
Cost range: The interior systems have a cost range of $70-$230 per linear foot in Canada – which is much cheaper than exterior systems.
Interior waterproofing may involve anything beyond the basement floor. Some spaces, such as waterproofing around floor drains, shower bases and utility sinks in the basement, are often neglected and can be important. Likewise, houses with wood frames close to the ground are treated with wood waterproofing to protect from rotting due to long-term exposure to moisture.
Pros: No effect on root cause of water pressure; foundation walls still are wet.
Cons: They’re not as effective at maintaining an entirely dry basement, but they can still help keep your basement dry.
What Is Exterior Waterproofing?
The most all-encompassing type of foundation waterproofing is exterior waterproofing. It deals with the problem before water ever comes in contact with your foundation wall.
This essentially means that the soil surrounding the home is dug around the home’s foundation and removed to the base. This is what is called proper wall waterproofing at the foundation level, the exterior surface of the exposed walls is cleaned, the cracks are repaired and the exterior of the wall is coated with concrete waterproofing compounds and a heavy duty waterproof membrane. A new weeping tile system (also known as a “french drain basement system”) is installed to divert water away from the building before it can cause pressure. Then everything is replaced and the land is filled in.
Exterior waterproofing is generally the right choice when:
- You’re experiencing significant foundation cracking or structural concerns
- Your home is in a low-lying area or has poor drainage common in parts of Oakville, Milton, and Niagara
- You want the most permanent, long-term solution available
- You’re doing a major renovation or landscaping project and excavation is already part of the plan
- There’s serious water infiltration coming through the foundation wall itself
Cost range: Exterior waterproofing costs about $100 to $300 per linear foot in Canada and the total cost from the size of your home to the condition of your soil range from $15,000 – $35,000.
Pros: Labor intensive, expensive, may be difficult to access, may need some extra time, may need to be repeated every 25+ years.
Cons: More disruptive, Time consuming, higher cost and requires excavation.
Interior vs. Exterior Waterproofing: A Side-by-Side Comparison
| Factor | Interior Waterproofing | Exterior Waterproofing |
| How it works | Manages water after it enters | Stops water before it enters |
| Disruption level | Low (interior work only) | High (excavation required) |
| Cost | $70-$230/linear foot | $100-$300/linear foot |
| Best for | Budget-conscious, finished basements | Long-term protection, structural concerns |
| Durability | 10-15 years with maintenance | 25+ years |
| Foundation wall protection | Indirect | Direct |
Note: Prices above are general estimates and may vary based on the property condition, repair complexity, and service company.
What Do Experts Actually Recommend? Interior vs Exterior Waterproofing
Most waterproofing professionals will have to admit that, This is dependent on your circumstances and frequently the best strategy is to go the two routes.
Interior systems are often the most practical and quick solution for older homes in the GTA that have a history of repairing wet basements, and finished basements. If exterior cracks are spotted in the foundation, if walls are moving or if there has been recurrent flooding in the home related to the groundwater, it is highly recommended to have full exterior waterproofing and exterior sealing done.
If in doubt, a professional evaluation is a must. A skilled contractor will assess the way you get water and where it’s entering your foundation, your soil type, the state of your foundation, and your drainage patterns before suggesting a solution.
Interior Waterproofing Is Best When:
- The basement has occasional leaks
- The issue is caught early
- Budget is limited
- You need fast protection
Exterior Waterproofing Is Best When:
- Water enters through foundation walls
- Structural cracks are visible
- Basement flooding happens repeatedly
- You want maximum long-term protection
In Many Cases, Experts Recommend Both
Interior waterproofing, in combination with exterior waterproofing gives the best protection for homes that really do have water issues.
This is often used in older homes in the GTA where there is an older drainage system and foundation, which can lead to flooding issues.
Don’t Overlook the Drainage and Plumbing Connection
Many homeowners don’t realize that the issue with water in the basement may stem from a plumbing-related cause. A wet basement problem can develop or get worse if any of the following issues are present: cracked or collapsed drain pipes, broken weeping tiles, or a sump pump that has become worn out or broken. In such instances, basement waterproofing is not the only solution.
When people notice water in their basement, they will think about looking for plumbers near me or a local emergency plumber and sometimes it’s the perfect option. If the problem is not related to ground pressure (sink damage in basement, broken plumbing supplies, failed floor drains, etc.), it’s a home plumbing problem, not a waterproofing problem, and you don’t need a waterproofing contractor, you need a residential plumber who specializes in basement plumbing.
Any plumbing emergency, such as sewage backing up into your floor drains, or a pipe bursting in your utility room, calls for the need of an emergency plumber near me, not an inspection. A good plumbing company that has after hours plumbing services will be able to come in the same day and cause only a few thousand dollars of damage.
When you’re in particular seeking a plumber in Mississauga or in any part of the GTA, it is better to select a firm that can provide both plumbers service and waterproofing solutions, as you’ll be able to find out everything at once as to what’s going wrong and the route to a resolution of the problem. When your basement floor gets wet at midnight, a reliable same day plumber who is knowledgeable in plumbing drainage is a priceless asset.
It is best to hire a team that is aware of both drainage and plumbing because of this.
Signs Your Basement Needs Waterproofing
Many homeowners ignore early warning signs until major damage appears.
Watch for these common indicators:
- Damp basement walls
- Persistent musty smell
- Mold or mildew growth
- Water stains on concrete
- Cracks in foundation walls
- Standing water after rain
- Peeling paint
- Increased humidity
- Wet carpet or flooring
- Recurring flooded basement issues
If these problems continue, they can eventually damage your plumbing system, insulation, drywall, and flooring.
FAQs
1. Is interior waterproofing a permanent fix?
Interior waterproofing is long term and very effective, but it deals with water, not its source. Most interior basement systems will run trouble-free for 10-15 years or more when the sump pump is installed and properly maintained. This is permanent because it keeps moisture out of your basement, but does not stop your foundation wall from being exposed to moisture.
2. How long does exterior waterproofing last?
A good exterior waterproofing having a suitable membrane and drainage system can be expected to last 25 years or longer. Many reputable waterproofing companies offer long-term or lifetime warranties for its exterior work. It is the most long-lasting option to protect your basement and foundation wall structure.
3. Can I do interior waterproofing myself?
If the dampness is small, it can be dealt with using surface sealants and simple moisture barriers, which are readily available at hardware stores and can be installed with ease. A complete interior drainage system and sump pump installation, however, will likely need to be done by a professional and will require an interior drainage permit. When not installed properly, poor installations can result in lost warranties and larger issues later on. If it’s more than just surface dampness, it is always better to call in professional waterproofing services.
4. When should I call an emergency plumber for basement water problems?
A plumbing emergency is when you suddenly have a flooded basement, an active burst pipe, sewage backup or a failed sump pump during a storm. You should only need a 24 hour plumber, not a waterproofing consultation. Rapid response minimises damage and the total cost of repairs is much less.
5. How do I know if my wet basement is a waterproofing issue or a plumbing issue?
Water which has come through after a prolonged rain or snow-melt is typically a waterproofing/drainage issue. When the water comes out without weather triggers or smells like sewage, it is probably a plumbing problem such as a broken pipe, sewer backup or broken drain pipe. These both issues are present in many cases and should be resolved concurrently.
Why Homeowners Across Southern Ontario Trust BOS Plumbing and Drains
With regards to maintaining a dry basement, experience is valuable. Since 2005, BOS Plumbing and Drains have provided a service to homeowners and businesses throughout the GTA, Mississauga, Oakville, Hamilton, Milton, Niagara and Cambridge, addressing issues in basement drainage, basement waterproofing and plumbing.
BOS is unique because they are able to see the big picture. Most contractors only do waterproofing or plumbing BOS does both, so they can be sure that if you have a problem in your basement it is not a drainage or plumbing problem, but rather a foundation or sump pump or drain line problem. One trusted team, one accurate diagnosis and a solution that works!
Their services include:
- Interior and exterior waterproofing consultation and referral
- French drain and weeping tile installation
- Sump pump installation, repair, and backup pump systems
- Basement drain repair and backwater valve installation
- Emergency plumbing response available as a 24 hour plumbing service across all service areas
- Commercial plumbing and residential services for properties of all sizes
- Full plumbing repair for all drainage and water management needs
If you’re a homeowner in Mississauga who’s having trouble with a leaking basement on an annual basis, or a property manager in Hamilton who is trying to find a dependable commercial plumbing service provider to help with a drainage problem, BOS Plumbing and Drains can assist.
The Bottom Line
There are two valid solutions – interior or exterior waterproofing – they are just different aspects of the problem. Water is well and efficiently used in the interior systems. Exterior – treats the source and provides the most long-term protection. Many households will find a good mix of the two to be the final solution.
The most crucial part? Don’t leave it to chance and purchase a solution without an experienced professional’s assessment.
Call BOS Plumbing and Drains today to get honest and knowledgeable advice from the team that’s served over 20 years in Southern Ontario. Whether it’s a quick check or a complete basement drainage system upgrade, they’ve got you covered.