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Interior vs. Exterior Waterproofing: Which is Best?

interior vs exterior waterproofing

Waterproofing your basement is a vital investment for any home. A leaky basement will lead to problems such as damaged building material, efflorescence on the walls, high humidity, and mould issues. These are big issues because the air that is in your basement is the air you breathe throughout your entire home.

But which method of basement waterproofing is best? Interior or Exterior? We’re going to walk through the pros and cons of each so that you can decide which solution will be best for your home.

A Brief Overview of Exterior Waterproofing

Exterior waterproofing is when the outside perimeter of the home is excavated to expose the foundation wall all the way down to its footing. The old footing drain is removed and a new one installed, which will direct water safely to a storm drain or sump pump. The wall itself is painted or covered with a waterproof material to stop water from entering through the foundation wall.

A Brief Overview of Interior Waterproofing

Interior waterproofing is when a small trench is dug around the inside perimeter of your basement to expose the old footing drain. The footing drain is replaced, which will direct water safely to a sump pump, and a waterproofing membrane is secured to the walls and sealed air tight. Water is permitted to enter through the foundation into the system, which is then discharged safely away from the home.

The Myth of Why Basements Leak

The myth that most people believe is that the most common cause of basement leaks is cracked or leaky foundation walls. But this actually isn’t true.

The most common cause of all basement leaks is a failed footing drain. The footing drain sits in the soil underneath your foundation. It directs water to either a sump pump, sewer line, or safe discharge spot away from your home.

However, the footing drain collects water that rises from underneath it. When the footing drain inevitably gets clogged or breaks, water is allowed to rise above it. This puts pressure on your foundation walls causing the cracks you see.

In both solutions, the footing drain will be replaced because it is the root issue of why basements leak. However, each solution has pros and cons depending on your home’s characteristics and your budget.

When Should You Choose Exterior Waterproofing?

If you have a finished basement already, exterior waterproofing may be the better choice. All the work to install this system is performed outside of the home, so no demolition will be required.

Exterior systems require little to no maintenance. They are designed to completely stop water from entering your basement at all. Once installed, they will last for a very long time.

Exterior waterproofing is a fantastic solution specifically for new construction builds because the soil around the home has not compacted yet. More details on that in the next section.

Things to Beware with Exterior Waterproofing

Exterior waterproofing is more expensive than interior waterproofing because it requires more labour and more materials.

Exterior waterproofing systems are more difficult to make fixes to if a part of the system fails because it is less accessible than interior waterproofing.

In order to install an exterior waterproofing system, you need enough space around your home to excavate the soil. Some buildings may not have enough space between lots, or cannot be excavated around the outside at all.

If you are waterproofing an older home or a used home, exterior waterproofing is not the best idea. The soil around your home has had many years to pack tight against your foundation wall. When that soil is removed then put back, it is significantly looser than before.

Water always follows the path of least resistance. You do not want to create a path of least resistance directly along your foundation wall. It is always better to have water slope and drain away from your foundation wall, not to gather and pool against it.

Finally, the newly installed footing drain sits on the outside of the foundation footing instead of underneath it. In areas with a high water table (like Windsor-Essex has), water can likely leak through the basement floor before it reaches the outside footing drain.

When Should You Choose Interior Waterproofing?

If your basement is unfinished, then installing an interior waterproofing system is the easy choice since no demolition is required.

Interior waterproofing systems are easier to make fixes to if a part of the system fails because it is more accessible than exterior waterproofing.

If you are more budget conscious, interior waterproofing is cheaper to install than exterior waterproofing because it requires less labour and materials.

If you are unable to excavate around your home, the default option is interior waterproofing.

Interior waterproofing is less complicated to install than exterior waterproofing, and is generally finished in 1-3 days depending on the size of the basement.

Interior waterproofing is fantastic for those who are planning on finishing their basement because it easily is hidden behind drywall and under the flooring.

Interior waterproofing systems have backup systems in place, such as a Battery Backup System, if the power goes out.

Things to Beware with Interior Waterproofing

Since interior waterproofing almost always relies on the use of a sump pump, the sump pump requires maintenance at least once a year.

Backup systems are technically an optional part of interior waterproofing systems. If the power goes out and the sump pump stops working, then your basement will flood.

If your basement is finished, a demolition will be required on the exterior walls to install the system.

Should I Waterproof My Own Basement?

No. It’s not that we don’t believe some homeowners are capable. While installing a basement waterproofing system is quite labour intensive whether outside or inside, it is better to have a licensed contractor install the system.

Some contractors, like Supreme Basement Solutions, are authorized dealers of tested and proven waterproofing products/systems that have fantastic warranties. You will miss out on the best warranties in the industry if you install it yourself.

As well, we often find foundation walls in need of support, mould that needs to be removed, or uncover surprise issues that should be addressed before the waterproofing system is installed. It’s important to have someone knowledgeable who can assess the full picture of your basement health so the issue is solved correctly and completely the first time.

Which Is Better? Exterior or Interior Waterproofing?

Both systems keep the inside of your basement dry. Each has their pros and cons that are more suitable or less suitable to each homeowner. The answer is whichever system has more pros than cons for your specific needs. We hope that this blog helps to weigh each option.

Looking to have your basement waterproofed? Give our experts a call to schedule your comprehensive assessment today!