External Waterproofing

External Waterproofing

Keeping water out is crucial for buildings, especially in vital areas like the basement and foundation. During construction or renovations, this will involve external/exterior waterproofing, which is the process of creating a waterproofing system that will disperse and direct moisture away from your foundation walls.

Areas with relatively high water tables generally experience increased hydrostatic pressure on the earth-retaining walls. Thus, external waterproofing is applied as the first line of resistance against this pressure. It works by blocking and/or reducing the passage of moisture through the external-earth retaining walls into the foundation/basement. 

brisbane waterproofing

External waterproofing systems

EXternal waterproofing systems usually consist of;

waterproofing concrete


This is the first step in most external waterproofing projects. During priming, the contractor applies a special spray to the external structure. The spray material narrows the masonry pores to create a water-repellent surface. Primers also bond with the waterproof coating applied in the next stage; primary waterproofing.

Primary waterproofing

In this stage, the contractor directly applies a waterproof material to the external wall. The material used typically has a high compression strength and can remain watertight even under high hydrostatic pressures.

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external waterproofing

Secondary waterproofing

This is basically the external waterproofing membrane. It serves some crucial functions in the external waterproofing system, including;

  • The membrane functions as a drainage system that directs water away from the external walls. This alleviates the hydrostatic pressure exerted against the building.
  • It protecs the primary waterproofing coating during the backifilling process.
  • It serves as a slip membrane as the backfill settles.

External membranes are dotted with numerous studs to creat a cavity that allows water to drain freely down the membrane to a drain. The waterproofing also has a geotex (internal polypropylene layer or fabric) that acts a filter. This filters out fine particles and dust, preventing them from entering the drainage system and causing a blockage.


For increased effectiveness, an external waterproofing system may include a drainage system. This is a combination of the external membrane and a land or french drain.

The contractor starts by digging a trench around the perimeter of the basement. They then lay a perforated pipe covered with crushed stones or gravel along this trench. When the water reaches the external membrane, it runs down the cavity and seeps through the gravel into the drain.  

For good practice, the land drains are usually wrapped in a geotextile membrane to filter out dust, fine sediments, and debris, preventing them from blocking the pipe.

external waterproofing
external waterproofing

Benefits of exterior waterproofing

External waterproofing comes with a lot of benefits. For instance, it stops moisture from seeping into your basement. This prevents the development of mould and other fungi, which are typically responsible for the presence of musty odours and allergens in the basement.

Note that the concrete used to construct foundations is not waterproof and, thus, susceptible to cracking and weakening due to water leaks.  Foundation damage is usually expensive to repair and may also trigger a whole host of other problems that may damage the rest of your home.

Fortunately, external waterproofing directs moisture away from the foundation and stops the above problems from happening. This maintains the structural integrity of your home/building, giving you peace of mind. It also means that you won’t have to incur costly home repairs and damaged personal belongings in future.

External waterproofing can even increase the value of your property. Potential homebuyers and property buyers are, on average, willing to pay more for a building with a waterproof basement than they are for one without.

Sunshine Coast external
waterproofing contractor

Queensland Waterproofers is the number one external waterproofing expert in
the Sunshine Coast area. So, if you’re planning an external waterproofing
contractor soon, call us today to book our services and get a free quote.

Frequently Asked Questions

Do you offer other waterproofing services?

Yes. Our wide range of waterproofing services includes bathroom waterproofing, concrete waterproofing, joint sealing, and carpentry.

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