Waterproof Membranes

Waterproof Membranes

Waterproof membranes are thin layers of water-tight materials that form a continuous waterproof layer over a surface. These layers don’t allow water to pass through and thus protect building structures from the adverse effects of moisture penetration.

This is usually done by adhering them around foundations, in bathrooms, balconies, and other water-exposed areas of a building. The material used for the membrane should be strong and tear-resistant. However, it should also maintain a considerable level of elasticity and flexibility that allows it to take any shape it’s laid over.

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Types of waterproof membranes

There are many types of waterproof membranes in the market.
These can be broadly categorised into liquid applied membranes and sheet-based membranes.

Sheet based waterproofing membranes

These membranes arrive at the construction site as rolls. During their application, they are unrolled and laid out on the waterproofing surface. Some of the most common sheet-based membranes include;

 1.    Self-adhesive modified bitumen

These membranes consist of asphalt infused with polymers, tackifiers, and/or mineral stabilisers. They are usually reinforced with polyester, fibreglass, or a combination of the two. While in rolls, the self-adhesive layers are usually protected with a release paper or film. This paper is removed during installation.
There are also some self-adhesive layers that are designed for prolonged exposure to the elements. Such products are typically surfaced with opaque surfacings like coatings, films, and mineral granules.

2.    Polymer-modified bitumen membranes

These are the most popular of all sheet-based waterproofing membranes. Their popularity is largely due to their immense durability and effective waterproofing properties. They can also withstand high mechanical loads and temperature fluctuations, and their additional flow resistance makes them suitable for very hot climates. During application, the underside of the material is melted using blowtorches to activate the tar-based adhesive.
Other types of sheet-based waterproofing are composite and PVC membranes. Composite membranes have a fabric base for increased tear-resistance and strength.  A chemical coats the fabric to provide this resistance.

Sheet-based waterproofing membranes are usually overlapped by about 4 inches (100mm) to form a waterproof joint. Unfortunately, these joints present the greatest weakness of sheet membranes and thus, must be done perfectly to prevent water penetration.

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Liquid applied waterproofing membranes

These waterproof membranes arrive on the site in liquid form. Therefore, they are applied through spraying or brushing over the surface. This allows for more control over the thicknesses of the impervious area. They also form seamless and joint-free membranes and are thus, considered superior to sheet-based membranes.

During application, contractors usually try to coat the entire area within a day to avoid forming cold joints. The liquid applied layer is then given time to cure and form a rubber-like elastomeric waterproof membrane.

If a concrete layer needs to be applied over a liquid-applied membrane, the material is first made rough by adding a thin layer of sand over the wet membrane. This is known as sand broadcasting and provides a rough surface for the concrete to adhere to.

Note that liquid applied membranes can break or tear if the layer is too thin.

Factors to consider when choosing a waterproofing

Usually, a competent waterproofing contractor- like Queensland interior linings- will survey the site and recommend the most appropriate waterproof membrane. However, it still helps to know some of the properties checked when selecting a membrane. These include: 

  • Elongation, which refers to the ability of the membrane to stretch. It is usually measured in percentages of the original length. Highrise buildings and those made from steel tend to move and thus, require a membrane with a relatively higher elongation than normal buildings.
  • Tear and abrasion resistance, which refers to the ability of the membrane to withstand wear and tear. Waterproof membranes are exposed to a lot of stress during construction. Therefore, the best materials are those which can withstand this stress without breaking.
  • Geometry and shape of the project. Liquid applied membranes are better than their sheet-based counterparts when it comes to waterproofing buildings with complicated shapes.
  • Chemical stability: The membrane must not react with the waterproofed structures or its environment.
  • Breathability, which refers to the ability of a membrane to release trapped water in form of water vapor.
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Looking for the perfect
waterproofing membrane?

Finding the best waterproof membrane for your home is easier said than done. So, why go
through the hassle when you can find a reliable waterproofing company to do it for you?
At Queensland Interior Linings, we use high-quality waterproofing membranes in all our projects.
Call us today to book our services or get a quote for your waterproofing project.

Frequently Asked Questions

What waterproofing membranes do you use?

Our choice of waterproofing membrane will largely depend on your budget and the nature of the project. However, you can be confident that we will use the highest quality waterproofing materials available to us.

Get a quote today

Do you need a reliable plastering or painting? We have a sister company that can do all interior linings and painting.
Get in touch with us today to get a free quote or discuss an upcoming project we might be able to help with.