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HOW TO WATERPROOF FOUNDATIONS FROM THE OUTSIDE?

Do you have a finished basement and want to protect it from water infiltration without having to strip the walls to access the foundations? You’ll need to waterproof your foundations from the outside. This method allows you to keep your basement intact and provides excellent protection against water and moisture for your concrete foundations.

In this article, our excavation specialists explain how to proceed. Let’s get started!

1 – EXCAVATE THE SOIL AROUND THE ENTIRE PERIMETER OF THE FOUNDATIONS

For external foundation waterproofing, the first step is to excavate the soil around the entire perimeter of the building. It’s necessary to dig down to the base of the concrete footing to gain full access to the foundations.

In some cases, this task may involve removing concrete sidewalks, a terrace, and landscaping, so a permit for public road occupancy may be required. If you want to limit the damage to your yard, you should consider hiring a company that offers residential excavation services. These companies are generally equipped with mini excavators capable of digging with precision.

If your property to be waterproofed is a condominium or a building with multiple units, the quickest and most practical solution is to hire a company that offers multiplex excavation services.

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2 – SEAL ALL CRACKS IN THE CONCRETE

Once the foundations are exposed, you’ll have an unparalleled view of their condition. You’ll be able to inspect them for cracks or defects, such as honeycombing, which are often the source of water and moisture infiltration problems in basements. If you detect any, they will need to be sealed to restore the waterproofness of your foundation walls.

Techniques like epoxy or polyurethane resin injection are ideal for sealing cracks in concrete and will prevent water from freely flowing between the exterior and interior of the foundations.

3 – ATTACH A WATERPROOF MEMBRANE TO THE EXTERIOR FACE OF THE FOUNDATIONS

The concrete used for building foundations is relatively porous. This means that even if there are no cracks, it can allow water and moisture to enter if the soil in contact with it is saturated with water.

To prevent water from reaching the foundations, a waterproof membrane must be attached to the exterior face of the foundations.

Different types of membranes can be used for foundation waterproofing in Quebec. There are synthetic rubber membranes (elastomer) and “cellular” membranes, composed of two layers separated by cells. The latter reduces water pressure against the foundation and allows for some drainage.

For maximum effectiveness, you should also cover the foundation footing with the membrane you choose. The membrane should also extend above ground level.

4 – BACKFILL THE TRENCH DUG AROUND THE FOUNDATIONS

Once the waterproofing membrane is securely attached, all that remains is to backfill the trench dug around the building.

However, before filling in this large hole, why not take the time to check the condition of your foundation drains? To ensure water drains there easily rather than reaching your freshly waterproofed foundations, you could cover it with clean gravel and geotextile fabric.

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In summary, waterproofing foundations from the outside involves four steps: excavation, sealing concrete cracks, installing a waterproof membrane, and backfilling. These are large-scale and difficult tasks. That’s why you should entrust them to professionals.

If your property is in Greater Montreal and you want to ensure that the excavation and backfilling work is done cleanly and meticulously, you can trust our excavation services. At Excavation Chanthier, we are proud to hold an RBQ license, which attests to the quality of our work.