Key Differences Between Cementitious and Liquid Waterproofing

When it comes to construction, waterproofing is one of the most important stages to get right. Without it, the very foundation (even a concrete slab) can be impacted as moisture works its way into the stability of the building, causing wood to deteriorate, grouting to loosen, and mould to flourish.

While there are several waterproofing methods and materials used in Australia, two of the most commonly used types are cementitious and liquid. While both are effective solutions in keeping water and moisture out of where they shouldn’t be, both have situations where they excel. Join us, as we explore the primary differences between cementitious and liquid waterproofing.

What is Waterproofing?

At its simplest, waterproofing is about applying a thin coating or a material that creates an impermeable barrier between a place where water and vapour should be and where it shouldn’t. For example, a shower needs to be completely waterproof so that all water is funnelled down the drain, not onto the bathroom floor and certainly not leaking into the walls around the shower.

There are several waterproofing methods, ranging from traditional waterproofing methods to modern materials, which can include a bituminous membrane or liquid-applied waterproofing. The types of waterproofing available also depend on the building or structure, whether that is concrete structures, including swimming pools, water storage solutions like water tanks, or even concrete slabs.

Provided there is adequate drainage, can stop water infiltration and are highly resistant to the elements, including the pressure of torrential rain and the harshness of UV exposure.

Ultimately, waterproofing is an essential process, preventing water damage from compromising the structure or its coverings. This helps ensure the longevity of the structure by dividing the building into wet areas and dry areas. Some common waterproofing materials include roofing materials (tiles and wrap), sheet membranes, and other construction materials.

The Importance of Waterproofing in Construction

Waterproofing is a critical stage of construction to stop water from affecting the structural integrity of the buildings. Whether from rain or plumbing, waterproofing material helps to prevent corrosion, rot, and mould, as well as the smell of dampness. While every building should be properly waterproofed, this is particularly important in areas that are often subjected to heavy rainfall and flooding.

Types of Waterproofing Materials

While there are several types of waterproofing materials, this article will focus on the respective strengths and key differences of cementitious and liquid waterproofing. However, it is helpful to be aware of additional alternatives used in the Australian building industry.

Cementitious Coating

As their name suggests, cementitious waterproofing coatings resemble cement and are composed of sand, both organic and inorganic compounds, as well as silica-based substances. They are applied as a thick, cement-like consistency, such as grout used to set bathroom tiles. This type of coating is easy to apply, and suitable for a wide range of applications and purposes.

Liquid Waterproofing Membrane

Liquid waterproofing membranes are applied as a thin layer of liquid rather than a paste using either a spray gun, a paint roller, or a trowel. Given their liquid consistency, this type of waterproofing material offers far greater flexibility and adaptability than cementitious coatings, making them also incredibly useful for a wide variety of applications.

Bituminous Coating

Bituminous membrane waterproofing uses bitumen (just like our public roads) to provide a waterproof seal an area from water. Extremely water-resistant, bituminous coatings also require additional equipment to apply properly, though they have an incredibly long lifespan of water-sealing effectiveness. This type of coating comes in a range of different formulations, so it can be applied with various methods.

Polyurethane Liquid Membrane

Polyurethane liquid membranes provide a seamless seal on the surface it is applied. Perfect for places where aesthetics are important, it is nonetheless relatively expensive and labour-intensive, as multiple layers of polyurethane will need to be applied. However, this type of waterproofing provides fantastic flexibility and adaptability and can be used for a wide range of purposes.

Characteristics of Cementitious Waterproofing

Definition and Composition

Cementitious waterproofing products are one of the most commonly used waterproofing products in the construction industry, due to its effectiveness and the widespread availability and affordability of its constituent materials. It is also incredibly effective over a long period of time, is easy to apply, and has a wide variety of uses, including setting tiles.

Advantages and Disadvantages

Given that its constituent materials are easy to find, and relatively affordable, cementitious waterproofing is a very cost-effective solution for a wide range of construction needs. Because it is easy to mix up a relatively large batch of this waterproofing material, it is one of the most commonly used waterproofing solutions. However, because it seals like concrete, it may not be suitable for areas subjected to high water pressure, as this can wear away at the “rock” over time.

Characteristics of Liquid Waterproofing

Definition and Composition

Liquid waterproofing involves applying a liquid formula to a surface to seal it from water and moisture intrusion. This type of waterproofing comes with varying strengths and weaknesses, though it is incredibly versatile and is suitable for almost all situations.

Advantages and Disadvantages

Liquid waterproofing provides a seamless membrane that can be applied to a wide range of building materials, including brick, wood, tiles, metal, fibreglass, and many others. However, it requires a meticulously cleaned surface before it can be applied, often needs more than one coat, and generally costs more than alternative waterproofing materials.

Comparison of Cementitious and Liquid Waterproofing

Comparison of Advantages and Disadvantages

Cementitious waterproofing is a more cost-effective solution than liquid waterproofing, while liquid waterproofing offers greater flexibility and adaptability and can be applied to a wider range of building materials. Cementitious waterproofing is also easier to apply, as liquid waterproofing may require professional installation. However, both provide excellent waterproofing properties, preventing water penetration or water seepage. It must be mentioned however, that the liquid waterproofing membrane method provides a thinner coating of waterproofing protection and so has a more flexible membrane if the various surfaces it is applied to are likely to expand or contract with the heat.

Applications of Waterproofing

Use as a Waterproofing Membrane for Basements and Foundations

Liquid waterproofing is an effective way to seal basements and foundations from ground moisture. As a liquid spray, it can be used to coat the walls, ceiling, and floor with layers of waterproof barrier to prevent water from leaking in from the outside, preserving the structural integrity of the building and its foundation. It also helps stop water leaks from spreading in the event water tanks (like the hot water system) encounter problems.

Use of Liquid Waterproofing for Wet Rooms and Bathrooms

Bathrooms, laundries, and other wet rooms are ideal for both types of waterproofing. Cementitious waterproofing provides an excellent barrier between and around bathroom tiles, while liquid waterproofing provides a membrane beneath the tiles as an additional layer of protection. Combining these approaches ensures a strong and resistant layer of protection, ensuring that water is draining away where it is supposed to and not leaking out and causing water damage.

Use of Liquid-Applied Membranes for Balconies, Decks, and Terraces

For use on balconies, decks, and terraces, as well as the external walls of a building, opt for layers of liquid waterproofing to coat those outdoor spaces with a barrier that keeps the rain outside. Fierce summer storms can see the rain coming in sideways, so waterproofing from floor to ceiling ensures your indoor spaces are protected from water ingress.

Use as a Liquid Roofing System

Liquid waterproofing is now commonly used as a roofing sealant too, especially for flat roofs that are becoming increasingly popular in modern home builds. Applied as a complete layer under the roofing material, the liquid roofing system provides a durable, weather-proof barrier, suitable for most conditions and most building materials.

Bituminous Membrane Waterproofing vs. Liquid Waterproofing

Differences in Composition and Performance

The primary difference between bituminous membrane waterproofing and liquid waterproofing is that the former is best used on low-slope roofs, while the latter is ideal for perfectly flat roofs. Liquid waterproofing also offers a greater degree of flexibility and is incredibly effective at filling in uneven gaps, frames, and structures.

Process of Waterproofing with a Liquid-Applied Membrane

Surface Preparation

To attain a clean seal, the surface to be waterproofed must be meticulously prepared beforehand. This means the surface must be clean, dry, and clear of any dirt, dust, or other debris. If the surface is not prepared properly, leaks and cracks can develop in the waterproofing material.

Primer Application

The next step is the application of a primer, which acts as a layer of adhesion between the surface and the waterproofing material. This helps ensure the longevity and effectiveness of the waterproofing material by giving it an extra strong bond to the surface it is applied.

Application of the Liquid Waterproofing Membrane

Once a primer is applied and has dried sufficiently, the liquid waterproofing membrane can be applied. Depending on the situation, liquid waterproofing can be applied via spraying or painting (with a paint roller or brush). In almost every case, liquid waterproofing is completely cold applied and does not require hot work.

Curing and Finishing

Layers are allowed to set before additional layers are applied, and once the final layer is complete, the membrane is allowed to cure. No specialised equipment is required for this, just the open air. However, curing times are affected by the specific product used, as well as local weather conditions.

Innovations in Waterproofing

The Use of Advanced Polymers in Liquid Waterproofing Membranes

The formulas used to make liquid waterproofing membranes are improving all the time. One such innovation is the use of advanced polymers, such as acrylics and latex, which have strong binding qualities that offer superb performance and protection.

A Focus on Sustainability and the Development of Eco-Friendly Products

As in many industries, there has also been a drive to develop (and a demand for) more sustainable and environmentally friendly waterproofing solutions. While all waterproofing materials must pass Australian Standard 4020 (AS 4020), which means they do not contaminate drinking water, some waterproofing materials are going above and beyond, with many manufacturers now avoiding the use of harmful ingredients like silica and petrochemicals.

Best Practices for Liquid Waterproofing

Professional Pre-Installation Assessment

Waterproofing is incredibly important, not just to maintain the structural integrity of a building, but to remove the impact that water damage can have on a building’s liveability too. To ensure a high-quality seal, it is highly recommended to get a professional evaluation of the site to determine the best course of action and the most efficient type of waterproofing compound for the build. Using a quality contractor with extensive experience in waterproofing will also help to ensure the roof’s integrity, maximise its longevity, and provide a finish that is both functional and aesthetic.

Maintenance Tips to Maximise the Lifespan of Your Liquid Waterproof System

A properly applied waterproofing protective barrier can last for decades, but only with the right maintenance and attention. Regular inspections are essential to assess the barrier’s integrity over time as it is subjected to weather and water. Finding an issue early means an easy (and cheaper) fix than letting a crack or split in the membrane widen over time.

Inspections should be conducted at least once a year, but for commercial liquid waterproofing it is best to schedule an inspection every 6 months, given the additional wear and tear that commercial buildings face as well as the costs involved in shutting down a business due to water damage or flooding.

Final Thoughts on Choosing the Right Waterproofing Solution

The right waterproofing solution for your next job will depend on a number of factors, including the building materials it will be applied upon, the local climate, and where in the building it will be applied. Additional factors to consider include the cost of sourcing materials, the ease of application, whether specialist equipment is required, and the overall performance of the applied compound.

Fortunately, your local team at Illawarra Industrial Supplies has all the answers to your waterproofing questions. With a wide range of coating and sealing products on offer, we can provide you with the materials and know-how to effectively and efficiently waterproof your next build. Call our friendly and knowledgeable team today to see how we can help you with all your waterproofing needs.