Exterior vs Interior Waterproofing: Which is Better?

Posted on: Nov 05, 2021


Close-up of exterior waterproofing in progress

For many property owners, the decision to have their basement waterproofed is a journey. The first fork in the road is whether to get professional waterproofing or just to “DIY.” If you’re reading this article, you may have either been disappointed with DIY waterproofing remedies or you’ve decided to trust the pros for a major upgrade like basement waterproofing. 

But now that you’ve decided to opt for professional waterproofing, you’re faced with another decision: to choose between exterior vs interior waterproofing. You may wonder which is more cost-effective, which would protect your basement completely from moisture, and which one is more feasible for your property. We’ll cover all this and more in our complete guide. 

Let’s get started!

Close-up of a French drain, or weeping tile system, installed for interior waterproofing

The Main Differences Between Exterior vs Interior Waterproofing 

As we’ve touched on in our article, “How Does Interior Waterproofing Work?” there are key differences between exterior and interior waterproofing. These include:

Where It’s Installed

The first and most noticeable difference is that exterior waterproofing, as the name suggests, is mostly installed from outside the basement. This means that excavation around the perimeter of the basement is required. Meanwhile, most of the installation work for interior waterproofing is done from inside the basement. 

The Necessity of a Sump Pump

Another difference is that a sump pump system is almost always needed for interior waterproofing. This is so that water doesn’t accumulate in the weeping tile network inside. The only way that a sump pump won’t be needed is if the weeping tile network can be connected to a storm sewer. 

Meanwhile, the necessity of a sump pump for exterior waterproofing would depend on the property’s unique needs (e.g. having a high water table). Furthermore, if a sump pump is to be used for exterior waterproofing, there is an option to have it outdoors because the weeping tile network of exterior waterproofing is also outside. The sump pump is also not entirely needed for exterior waterproofing to keep water out, but it is a great way to keep accumulated water from pooling around the waterproofed foundation. 

The Absence of Leakage 

Finally, the third key difference is that exterior waterproofing is designed to keep water out completely. This means that once exterior waterproofing is in place, water cannot touch the basement wall. 

Meanwhile, interior waterproofing cannot completely prevent water from seeping through the wall itself. However, interior waterproofing will still manage to keep the basement space dry through the strategic use of the waterproof membrane and weeping tiles. 

Now that we’ve laid out the key differences of exterior vs interior waterproofing, this will provide the necessary context as we talk about the factors to consider when choosing between the two.

Factors to Consider When Choosing Between Exterior vs Interior Waterproofing

1. Excavation Area Around Your Basement 

This is the first crucial factor to consider because excavation space around your property’s foundation is required for installing exterior waterproofing. Therefore, for properties that don’t have enough excavation space or don’t have excavation space at all, the automatic best choice would be interior waterproofing. 

2. Full Moisture Protection 

Both waterproofing methods can be set up so that the basement space itself is dry and free of puddles and leaks. However, this is achieved differently for exterior vs interior waterproofing methods. 

For exterior waterproofing, the waterproof membrane is set up on the outside of the foundation, meaning water can no longer touch the foundation wall. This is paired with a matching weeping tile system to manage moisture in the soil.  

As for interior waterproofing, a trench and weeping tile network are set up at the base of the leaky basement walls. This network catches the leaks that go through the basement walls and the water is expelled through a sump pump. 

In addition to all these, a waterproof membrane is installed on the internal surface of the leaky walls to serve as a vapour barrier. From this setup, we see that with interior waterproofing, water may still seep through the basement walls. However, everything is managed efficiently and covered by the barrier. 

3. The Intended Use of Your Basement 

In relation to the previous factor discussed, some homeowners may prefer exterior waterproofing over interior waterproofing based on the use of the basement. For basements that are intended to be long-term living spaces like bedrooms, home offices, or rentable spaces, exterior waterproofing would be the preferable choice. Relatively speaking, exterior waterproofing keeps the space “drier” and won’t rely on a running sump pump to do so. 

Basement bedroom that has undergone exterior waterproofing

4. The Invasiveness of the Project 

Based on how the exterior waterproofing system is installed, which is mostly from the outside of the basement, it is considered a less invasive form of waterproofing. This is opposed to interior waterproofing which requires the creation of small trenches from inside. 

This means that interior basement waterproofing may require the basement to be cleared out for the installation to take place. In case decreased invasiveness is a key factor for you, exterior waterproofing would be the better option. 

5. How Long the Waterproofing Will Last 

In general, exterior waterproofing lasts longer without maintenance than interior waterproofing. This is mainly because interior waterproofing almost always relies on a sump pump to keep the space dry. However, in some cases, interior waterproofing can be linked to a storm sewer instead, meaning a sump pump is not required. 

Furthermore, for both of these waterproofing types, it is important to note that the quality of the materials and the thoroughness of the installation contribute to how long the waterproofing will last.  

6. Your Budget

Generally speaking, interior waterproofing is more affordable than exterior waterproofing. However, this is just considering the upfront cost. The added price of exterior waterproofing could well be worth it, factoring in that it generally requires less or no maintenance at all. 

Reliable Exterior or Interior Waterproofing From Seasoned Professionals 

This guide covered the differences between exterior vs interior waterproofing and what factors to consider when choosing a waterproofing method for your property. If you’re still not sure which one to choose, we’re here to help!

As one of the most trusted waterproofing companies in the GTA, we at PRO Waterproofers have worked on numerous properties installing interior and exterior waterproofing systems. We make use of top-notch materials and innovative techniques to keep our clients’ basements dry for years to come.

If you have questions for us or you’d like to avail of our FREE in-home consultation, contact us today! 

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