What is Basement Waterproofing

What is Basement Waterproofing

What is Basement Waterproofing

Just above the foundation of a building, the basement may be partially or completely buried. This contact of the masonry structure with the ground implies numerous constraints, both mechanical (weight of the construction, ground pressure, etc.) and in terms of waterproofing against water, humidity, plant roots and insects. The waterproofing of the basement is an essential phase not to be neglected during any construction.

Waterproofing the basement: why?

Basement protection is an obligation of masonry and construction. But the protection of the base is not limited to the installation of a waterproofing sheet that provides mechanical insulation and possibly drainage. The waterproofing of the basement is done directly on the masonry before the protection is installed in order to achieve efficient insulation between the backfill earth and the masonry walls.

Levels of waterproofing of the basement

There are two levels of waterproofing of the basement (excluding mechanical protection):


What is Basement Waterproofing

Waterproofing is limited to preventing the passage of water (mineral salts, insects, roots…) but allows the base material to breathe thanks to air exchanges.

Strict waterproofing

The waterproofing itself consists in blocking the passage of water (mineral salts, insects, roots…) but also of air loaded with humidity which is a source of condensation.

Which product is for the waterproofing of the basement?

The product or material to be applied to the basement depends on the type of waterproofing. Waterproofing products are found in the form of paint or coatings that are applied by spraying or spreading directly on the masonry. There are two main families of waterproofing products: grey products, which are cement-based coatings, and black products, which are bitumen-based and are applied like thick paint. Waterproofing products are flexible coatings made of elastomeric bitumen, which are generally presented in the form of a rubbery film with which the entire subfloor is wrapped and previously treated with a primer. These waterproofing products (water and air) are distinguished according to their method of installation.

Weldable laminates: the film strips are welded together during application with an overlap to create a completely waterproof membrane that also adheres to the substrate by welding. This is a moderate heat welding method that does not require any specific knowledge and a simple welding flashlight.

Bonded laminates: the strips are cold bonded to each other with sufficient overlap, but also to the wall with the primer that has been applied.

Good to know: we classify the levels of waterproofing of the walls in two categories. When the walls of the premises cannot support any trace of moisture (living spaces, offices, game rooms or movie theatres…), they are classified in the first category, which requires the use of a waterproofing product for the basement. The walls of non-habitable premises that can bear some traces of moisture (boiler room, cellar, garage …) are placed in the second category, which requires only the installation of a coating or waterproofing paint.

What you should know before buying

Basement mortars are the least expensive because they are waterproofing mortars and not waterproofing films. Waterproofing mortars are industrial mortars to which an additive is added (water repellent, waterproofing, super-plasticizer…). You can buy the mortar of the sub-base ready to use in a bag and do it yourself or make it entirely by buying only the adjuvant.

Elastomeric bituminous films, as well as bonding primers, can be purchased according to the type of installation you wish to carry out (welding or bonding), making sure to use compatible products.

Availability of basement waterproofing products

The main waterproofing products (Afitex, Axter, Mapéi, Parex, Lanco, Sika, Siplast, Soprema, Weber & Broutin…) are available on the Internet as well as in do-it-yourself stores or at construction supply stores.

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