Comparing GRP Fibreglass Roofing and Single Ply Systems Like Sikaplan and Sarnafil

tsalomone79
Oct 6, 2025
4 min read

Updated: Nov 5, 2025

Making a roofing decision can be overwhelming, especially with various options available. GRP (Glass Reinforced Plastic) fibreglass roofing and single ply systems such as Sikaplan and Sarnafil each offer different features that can benefit construction clients. This post will provide a clear look at these systems, helping you choose the right one for your project.

Understanding GRP Fibreglass Roofing

GRP fibreglass roofing is highly regarded for flat roofs due to its robustness and weather resistance. It is made from fibreglass mats soaked in resin, forming a strong and waterproof layer.

One of the key advantages of GRP roofing is its impressive durability. With proper installation, a GRP roof can last over 30 years, making it a smart long-term investment. According to some studies, 93% of homeowners rated the longevity of GRP as a top benefit. Additionally, GRP materials weigh less than traditional roofing, easing the load on the building's structure.

However, the installation process requires skilled labour. Working with resins and required curing times can raise initial costs compared to simpler roofing options.

Advantages of GRP Roofing

Durability: GRP roofing is resistant to UV rays, chemicals, and extreme weather, ensuring it lasts longer. For example, its lifespan is often compared to materials like metal and traditional asphalt systems.
Seamless Finish: The method of application provides a continuous surface without seams, leading to a lower chance of leaks.
Low Maintenance: Once installed, GRP roofs don't need frequent attention, reducing upkeep stress for property owners.
Aesthetic Flexibility: GRP can be easily formed into various shapes and colours, allowing for design creativity. For instance, it can replicate the look of other materials, like slate.

Disadvantages of GRP Roofing

Installation Complexity: The need for specialized skills can make installation more expensive compared to other systems.
Curing Time: The resin requires specific conditions and time to set, which may extend project timelines.
Temperature Sensitivity: Installation can be impacted by fluctuating temperatures and humidity, affecting the final quality.

Exploring Single Ply Roofing Systems

Single ply systems, such as Sikaplan and Sarnafil, represent another solid choice for flat roofs. These systems consist of one layer of synthetic material, often made from PVC or TPO, and are either mechanically attached or glued to the roof deck.

A standout feature of single ply roofing is its ease of installation. The lightweight materials often allow for quick application. Installations can be completed up to 40% faster compared to GRP, which can lead to significant savings in labour costs.

Moreover, single ply systems tend to be energy efficient. Many products are designed to reflect sunlight, potentially lowering electricity bills by as much as 20% for cooling in warmer months.

Advantages of Single Ply Roofing

Quick Installation: The straightforward process allows for faster project completion, which is particularly beneficial for tight deadlines.
Energy Efficiency: Many single ply materials reflect UV rays, helping reduce energy costs significantly in climates with high sun exposure.
Cost-Effective: The installation speed often translates to lower labour costs, making single ply systems a more economical choice upfront.
Repair Flexibility: Single ply membranes can be easily patched or replaced when damage occurs, simplifying maintenance.

Disadvantages of Single Ply Roofing

Vulnerability to Punctures: Compared to GRP roofing, single ply membranes might be more prone to punctures and tears from sharp objects.
Limited Lifespan: Many single ply systems can last 20 years or more, but they generally do not surpass the lifespan of GRP roofing.
Seam Issues: The seams in single ply membranes can weaken over time, potentially leading to leaks if not carefully addressed during installation.

GRP vs. Single Ply: A Direct Comparison

When weighing GRP roofing against single ply options such as Sikaplan and Sarnafil, consider the following factors:

Longevity

GRP roofing, if installed correctly, generally lasts longer than single ply systems. It often proves to be a more worthwhile investment for those planning on keeping the building long-term. Single ply systems, on the other hand, can last between 20 to 40 years. For example, Sarnafil offers a 40-year guarantee, while GRP roofing typically comes with a 25-30 year warranty.

Installation

Single ply systems shine in quick installation. If a project has tight timelines, these systems may be ideal for faster setup.

Maintenance

While both options require little upkeep, GRP’s seamless finish can lower the risk of leaks, providing peace of mind.

Cost

Single-ply membranes (Sika/Sarnafil type) typically have higher per-m² material costs than the resin and matting cost of GRP.

Labour cost: GRP involves more labour and is slower; single-ply is faster to lay (especially on simple roofs). Labour savings can offset the higher material price.
Installed cost (typical): For small or simple roofs, GRP can be competitive or cheaper because material costs are lower. For larger roofs, single-ply often wins on installed cost because of speed and economy of scale. Exact numbers vary regionally and by contractor—always price both with local installers.
Lifecycle & maintenance cost: Single-ply systems are easier and cheaper to inspect and repair (weld or patch). Manufacturers offer system warranties and often single-source warranties that can reduce lifecycle risk. GRP is low-maintenance, but when repairs are needed, they require specialists.

Weighing Your Options

Choosing between GRP fibreglass roofing and single ply systems like Sikaplan and Sarnafil comes down to your particular needs and circumstances. If you prioritise durability and longevity, GRP roofing could be the best choice. However, if you need a quick and affordable solution, single ply systems might better suit your requirements.

As a construction client, take the time to carefully consider the strengths and weaknesses of each roofing type. Understanding these differences will empower you to make an informed decision that meets your project’s goals and lasts for years to come.

Conclusion

In conclusion, both GRP fibreglass roofing and single ply systems have their unique benefits and drawbacks. The choice ultimately depends on your specific needs, budget, and project timeline. I encourage you to weigh these factors carefully.

For those who value longevity and durability, GRP roofing is a strong contender. On the other hand, if you are looking for a quick installation and cost-effective solution, single ply systems may be the way to go.

By making an informed choice, you can ensure that your roofing project meets your expectations and serves you well for years to come.