When to Choose a Sheet Waterproofing Membrane for Your Project

The effects of water-related damage post-construction can turn a successful build into a compromised structure with a costly problem to fix. Water penetration is one of the most persistent and damaging problems faced by a building project, whether the moisture comes from extreme weather conditions, flaws in the installation process, or choosing the wrong waterproofing solutions for a specific project.

Choosing the right waterproofing membrane can be the difference between decades of structural integrity and the failure of fasteners, joiners, timber frames, or even the foundation. Selecting the right membrane type from the wide variety of industry options on offer may seem like a headache but knowing when and when not to use sheet vs liquid membranes is simpler than most people think.

What Is a Sheet Waterproofing Membrane?

Sheet membranes are prefabricated, flexible sheets of waterproofing material that can be rolled over an area to form an impenetrable, waterproof barrier. Sheet systems protect both above- and below-grade areas (above or below ground) and are a versatile and strong membrane system.

Sheet membranes come in a variety of common materials:

Whichever material you choose, sheet membranes are highly versatile waterproofing solutions that, when installed correctly, provide seamless coverage to areas exposed to water and moisture.

Sheet Membranes vs Liquid-Applied Membranes

One of the most significant choices during a construction project is which waterproofing system to install: sheet membranes or liquid-applied waterproofing.

While both have their pros and cons, each option has its specific situations in which it thrives.

When to Use a Sheet Waterproofing Membrane

Sheet waterproofing membranes are ideal for a wide range of construction projects, including:

• Below-grade structures: Highly resistant materials, seamless coverage, and no need for curing time, which makes all the difference for below-ground applications, such as in basements or tunnels.
• Green roofs and balconies: PVC sheet membranes offer complete UV resistance, so they are perfectly suited for use where waterproofing membranes may be exposed to daily sunlight.
• Areas with high water pressure: Consistent thicknesses and a reduced chance of improper installation mean sheet membranes are more likely to hold up under high water pressure.
• Projects requiring factory-controlled thickness: For projects requiring manufactured precision, opt for the easy installation of sheet membranes over liquid membranes, which require greater technical skill and specialised tools to apply seamlessly.

While the type of construction project affects which type of membrane to use, the location and local environmental factors can also influence which waterproofing option will be the most effective.

It is important to review the performance requirements of waterproofing on site before application, especially if the site is subject to extreme environmental conditions, including storms or periods of heavy rainfall, or scorching summers and/or frosty winters. Extreme temperature fluctuations can also cause structural movement as materials expand and contract, impacting substrate compatibility.

Key Advantages of Sheet Membranes

One of the main advantages of sheet membranes is their pre-manufactured uniform thickness. This means there is no chance of uneven film build. There are no high or low points if the thickness of the chosen waterproof system.

A high resistance to water pressure is another of its unique advantages. Because sheets are pre-manufactured to be perfectly even, there are no weak spots for high water pressure to exploit, like there may be in unevenly applied liquid membranes.

Another advantage is fast installation and no need for proper curing, resulting in lower labour costs and immediate seamless protection. Pre-formed lap joints create a better seal, providing seamless application and complete protection from water damage in wet areas.

Challenges or Limitations of Sheet Waterproofing

Unfortunately, sheet waterproofing does face some minor challenges. First, is that the surface to be laid must be prepared and cleaned before application to ensure a smooth and uninterrupted adhesion. Dirt or debris between the surface and the sheet may cause the sheet to lift over time.

Second, sheets will have to be cut or modified to fit rooms with complex geometry. Some installation expertise may be required for areas of unusual shape, such as small bathrooms, where seam vulnerability may be increased if more complex detailing is not performed.

Finally, sealing around penetrations, like pipes or cables running through the floor, can present a challenge. It is important to form a complete seal around all holes to ensure water damage does not form in the building’s most vulnerable locations.

Questions to Ask Before Choosing Your Waterproofing

Before you choose your waterproofing option, ask yourself the following questions to ensure you’re making the right choice:

What is the substrate condition like? If it is relatively flat and can be cleaned and prepared properly, then go for sheet waterproofing. However, if the substrate is uneven and irregular, liquid membranes might be the way to go.

Will there be exposure to UV or chemicals? If so, opt for sheets made from resistant materials. For example, PVC sheet membranes have excellent UV protection properties, while HDPE is highly resistant to chemical corrosion.

Is long-term durability critical? If yes, then sheet membranes provide a highly versatile and durable solution for waterproofing.

Ready to Waterproof Your Next Job? Get in Touch With the Experts

The choice of which waterproofing option is the best for your next construction or renovation job can be a difficult one to make. While we have covered the benefits of sheet membranes vs liquid membranes, we have also just scratched the surface of the wide range of waterproofing solutions on offer.

We always encourage you to dig deeper before purchasing and applying waterproofing. Fortunately, Illawarra Industrial Supplies is here to help. Contact our friendly and knowledgeable team today for an expert assessment or product recommendation for your next waterproofing job!

Frequently Asked Questions

When should you use membrane waterproofing?

Membrane waterproofing should be used whenever there is a risk of water entering an area it shouldn’t. This includes throughout the roof, around the bathroom (particularly near sinks, baths, and showers), and in outdoor areas subject to rain, among many others.

How do I choose waterproofing materials?

Choosing the right waterproofing materials depends on your budget, the area to be waterproofed, and the local environmental conditions of the site.

Which water-resistant sheet is used in construction?

Common water-resistant sheets used in construction include PVC and bituminous sheet membranes, each chosen based on the project’s requirements.

What are the different types of waterproofing membranes?

The two main types of waterproofing membranes are sheet and liquid, but there are subtypes of both that also have their own properties and ideal situations in which to use them.