The right waterproofing system for your commercial or residential building needs to ensure that no water ingress, and subsequent damage, occurs.
However, knowing which system, liquid or sheet waterproofing membranes, will depend on the particulars of your application.
Both of these waterproofing solutions offer unique substrates, details and constraints. In this article, we’ll introduce you to some of the factors you need to take into account when choosing the right system for your project.
To learn more about BIM Remedial Sydney’s remedial waterproofing services click here.
What Is the Difference Between Liquid and Sheet Membranes?
Liquid Membranes
In essence, liquid membranes are a waterproofing solution applied onto a surface as a wet coating. The coating then cures into a seamless and flexible barrier to ensure no water ingress due to exposure to other liquid or moisture.
Liquid membranes:
- Applied with a roller, brush or spray
- Can take multiple coats to ensure it is most effective
- Cures into a continuous, joint‑free film
- Made from polymer, polyurethane or similar chemicals
Sheet Membranes
On the other hand, sheet membranes are pre‑formed rolls (i.e., sheets) that are then placed over the substrate and have laps and joints.
Sheet membranes:
- Sheets supplied in factory‑made form
- Installed with laps, adhesives or heat‑welding
- Commonly made of bituminous, PVC, TPO or similar industrial materials
Ultimately both liquid membranes and sheet membranes meet regulatory requirements and when properly manufactured and applied can ensure effective waterproofing.
When Is Liquid Membrane Waterproofing the Better Choice?
A liquid membrane is usually the better choice when the substrate is one or more of the following:
- Complex
- Heavily detailed
- Subject to movement
- Subject to restricted access
Because liquid membrane waterproofing offers seamless coverage it is best for projects where there is irregular geometry that could allow water to seep through. If using sheet membranes would be slow, difficult or imperfect, liquid membranes are ideal.
What are examples of complex detailing?
Think balconies with various posts or balustrades, or roofs with plant plinths, penetrations and falls changes.
What kind of movement could occur?
If you’re applying waterproofing on a suspended slab subject to thermal or structural movement, or you have junctions that need bond breakers or coves, liquid membranes are likely the right choice.
What are examples of restricted access?
If reaching the surface is tight or the area needing waterproofing is confined to podium edges, a liquid membrane is likely your best option.
When Is Sheet Membrane Waterproofing the Better Choice?
Sheet membrane waterproofing is usually the better choice when the substrate is one or more of the following:
- Large
- Relatively flat
- Consistently thick
- In need of high mechanical durability
Because sheet membranes are mass produced the factory‑controlled production ensures reliable and consistent performance once all laps and terminations are detailed and with professional installation.
What are examples of the right applications?
Consider sheet membranes when you are working on broad and simple applications like large roof decks or basement external walls.
Which membrane is best for high traffic areas?
Applications subject to high levels of impact or traffic would benefit from the instantaneous impenetrability of sheet membranes. The factory-controlled products are robust in terms of puncture and tear resistance.
How Do Liquid and Sheet Membranes Compare?
1. Which is easier to apply?
Liquid membranes are brushed, rolled or sprayed in liquid form. Whereas sheet membranes are rolls or sheets that are simply laid and therefore easier to apply.
2. Which is better for seams and joints?
Liquid membranes offer a seamless and monolithic barrier, while sheet membranes require more effort and special customisation to ensure seams are watertight.
3. Which is better for complex detailing?
Liquid membranes allow for easy application around complex detailing items like penetrations, corners and curves. Sheet membranes are easier applied across large surfaces, and can be more challenging and labour intensive on complex detailing projects.
4. Which is better for thick applications?
Liquid membranes can vary for thick applications based on application whereas sheet membranes allow for consistent and easy thick application.
5. Which is better for durability in high traffic areas?
While both liquid and sheet membrane waterproofing can be effective, sheet membranes are easier for ensuring ongoing puncture and tear resistance.
6. Which is better for ongoing maintenance?
Liquid membranes require re-coating, though being able to do so in a localised and targeted way is usually simpler. Sheet membranes may require less ongoing maintenance but if damaged can require more labour-intensive solutions to fix.
7. Which is better for programming and curing?
Liquid membranes generally have longer cure times. Whereas, sheet membranes are functional immediately from installation.
8. Which is better for industry standards and compliance?
Both waterproofing solutions can meet the material and application requirements of Australian industry standards.
Liquid vs. Sheet Waterproofing Membranes - Frequently Asked Questions
What Australian Standards influence waterproofing membrane choice?
In Australia, all above‑ground waterproofing membranes must comply with regulatory standards AS 4654.1 which deals with materials and AS 4654.2 which deals with the design and application. This applies regardless of whether the system is liquid or sheet based.
For remedial works, your choice of membrane also needs to align with the NSW Design and Building Practitioners Act (DBPA) framework. This is why we recommend choosing a certified and expert waterproofing remedial specialist. The team at BIM Remedial Sydney have an intimate understanding of the standards, obligations and regulations for assured compliance.
Do liquid or sheet membranes last longer?
Both waterproofing solutions deliver long lasting protection when professionally supplied and installed.
Are liquid membranes more prone to application error?
Liquid membrane effectiveness depends heavily on surface preparation. That is why having the correct film build and curing conditions is important. With sheet membranes seams and terminations are a risk point, so high‑quality detailing is important for durable, watertight joints.
How Do You Know Which Membrane Is Right for Your Building? Call BIM Remedial Sydney
The safest approach when it comes to selecting the right waterproofing solution is to ensure a professional, tailored diagnostic inspection of your application and needs.
With BIM Remedial Sydney, our specialist will conduct a context-specific assessment to consider existing defects, complication, lifecycle, staging, membrane-preference and Australian Standards/DBPA compliance.
Our contractors’ expertise is in providing reliable remedial waterproofing for any application. Whether you need a large-scale sheet membrane application or complex liquid membrane solutions, make sure to reach out to the BIM Remedial Sydney team today.
