Flat roofing materials have immensely grown in popularity over the recent years, due to the advancements in technology and installation processes. From extensions and garages to commercial buildings and outbuildings, flat roofs are suitable for a range of applications with different materials and methods.

Two of the most common flat roofing materials are GRP/Liquid membrane and EPDM – but which is best for your particular project? Both GRP and EPDM flat roofs have been around for a while. However, recent advancements in the application methods, as well as the growth in health and safety concerns associated with traditional torch-on roofing, have led to the recent popularity growth of EPDM and GRP/Liquid membrane roofing.

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At Royal Roofing, we are happy to offer services related to both GRP/Liquid membrane and EPDM(Note: Royal Roofing not offering at the moment) flat roof types. Below, we have summarized some of the key points to keep in mind to help you determine which type of roofing material is best for your project:

What is EPDM Roofing?

“EPDM” stands for “Ethylene Propylene Diene Monomer,” which is a type of rubber roofing. EPDM is a durable material, which is supplied in rolls ready to be applied across the roof surface.

What is GRP Roofing?

“GRP” is short for “Glass-Reinforced Plastic,” which is also known as fibreglass roofing. GRP material consists of resin with fibrous or glass strands that reinforce the material. Even though the resin is liquid originally, it can be cured into a solid relatively quickly by applying a catalyst.

Physical Composition

EPDM Roofing

Being a rubber-like material, EPDM is incredibly flexible, which makes it ideal for roofs with uneven structures or roofs featuring pipes, skylights, and gutters. The rubber material is difficult to break, which means that it will not be easily damaged by impacts such as falling items. Furthermore, EPDM’s flexibility allows for expansion and contraction, thus reducing the risk of cracks. In fact, EPDM roofing installed by Royal Roofing can safely expand up to 300% in length and return to its original size.

In addition, EPDM is impermeable yet breathable. This means that moisture, vapours, and smoke cannot enter the roof space; at the same time, the moisture and heat can easily escape from the roof to prevent damp, rot, and structural damage.

EPDM has excellent waterproofing qualities, which makes it ideal for a variety of applications like pond liners and seals. It is also resistant to saltwater, which makes it suitable to be used on properties near the coast.

GRP Roofing

GRP roofing is known for its outstanding strength-to-weight ratio, which allows good strength properties to be achieved with less material. In addition, other unique properties of GRP allow it to be moulded to almost any shape, over and around uneven structures and irregular roof surfaces.

Finally, GRP has excellent corrosion resistance. As such, it can be safely installed on roofs near commercial buildings that handle chemicals or factories.

Installation Processes

EPDM Roofing

EPDM roofing is supplied in rolls of material that can be easily unrolled across the roof. With a relatively easy installation process, EPDM roofing consists of just a single sheet of rubber-like material. The material is glued to the roof surface, and then trimmed to fit around the edges. EPDM roof kits are often sold with all the items required for installation.

While EPDM roofing can be installed in a DIY fashion, working with professionals from Royal Roofing can ensure the quality and longevity of the roof. If the installation process isn’t followed exactly, it can cause serious problems with your EPDM roof.

GRP Roofing

As compared to EPDM, GRP roof installation requires a slightly more complicated process, with more than simply laying down rolls of material. In order to install GRP roofing, you would need to add a layer of resin, then lay a mat of fibreglass strands, followed by another layer of resin. Then, the topcoat must be applied to ensure weatherproof qualities.

While there are numerous GRP roof kits available on the market, the inclusion of several resin layers and catalysts can make GRP installation more challenging for DIY-ers. Furthermore, GRP roofing can only be installed in completely dry weather conditions and temperature above 50° F (10° C). Luckily, with Royal Roofing, you have nothing to worry about: we will be happy to take care of your GRP roof installation from A to Z.

Roof Appearance

EPDM Roofing

While incredibly versatile and easy to install, EPDM roofing is often not the first choice due to its aesthetics. EPDM is just a large piece of rubber on top of a roof, and it looks accordingly. However, this comes down to personal preference, – many people don’t worry about the look of EPDM roofing, as it isn’t often visible from the ground.

GRP Roofing

A finished GRP roof, on the contrary, has an unarguable aesthetic appeal. Seamless, clean, and available in a variety of colours, GRP roof definitely wins in the appearance domain.

Roof Longevity

Both EPDM rubber roofing and GRP/Liquid membrane roofing have an expected lifespan of around 15-20 years. Most roofs start experiencing leaks over time if seams wear out or are not sealed properly to begin with. Luckily, neither GRP nor EPDM roofs have seams, which contributes to a significantly longer lifespan.

EPDM roofing material is elastic, which allows for safe thermal movement like expansion and contraction. Even in fluctuating temperatures, EPDM roofing will not experience any cracks or splits.

GRP is extremely waterproof, which makes it a popular choice for marine applications, such as on the hulls of boats. EPDM material is waterproof as well; it is commonly used in seals, valves, and pond liners.

Neither GRP nor EPDM is affected by the sun, – it will not blister, crack, or rot with sun exposure, unlike most other flat roofing materials. In addition, compared to other roof materials, GRP is the least likely one to develop moss over time.

Roofing Repairs

EPDM Roofing

Small holes or tears in EPDM roofs can be repaired relatively quickly. Our roofing professionals can take care of all the necessary repairs; plus, there are a number of EPDM roof repair kits available on the market if you wish to attempt the repairs yourself. In fact, rubber roof repair can be as easy as patching up or sealing the damaged areas.

GRP Roofing

When it comes to GRP roofing, repairs can be a little more complicated. However, even GRP roofs can be patch repaired with special repair kits. While regular roof repair kits can only guarantee short-term fixes, special GRP roof kits can allow for longer-term repairs. With a special GRP patch repair kit, you would start by sanding down the area; you would then apply a new chopped strand mat, as well as resin and a topcoat. Short-term roof repair kits, on the other hand, usually involve the application of an acrylic sealant.


EPDM Roofing

Made from recycled materials, EPDM is relatively inexpensive. EPDM roofs can be installed with relatively generic tools, which means that you won’t likely need to purchase any additional tools if you decide to go a DIY route. In addition, the elasticity and flexibility of EPDM roofing mean that deterioration will be minimal overtime, keeping the repair and maintenance costs low.

GRP Roofing

As compared to EPDM, GRP roof installation requires more specialized products and tools, which leads to higher roof installation costs. Moreover, GRP roofing is difficult to install by yourself, – it is recommended to hire a roofing contractor instead, which further increases the overall costs. However, as compared to traditional roofing, GRP material is less likely to require repairs in the future, which would save you money in the long run.

So, which is better?

The decision of choosing EPDM or GRP roofing material ultimately comes down to the project at hand. For example, if you are looking for an affordable, easy-to-install roofing material, EPDM will be the ideal option for you. However, if you prefer better aesthetics and durability, GRP will be the right choice.

Today, both roofing products are easier to use and more affordable than ever before. Both EPDM and GRP materials have similar excellent qualities, as well as unique ones that make them ideal for different specialized applications.

Still not sure whether EPDM or GRP material is best for your roof? At Royal Roofing, we can help you make the right decision and take care of the roof installation from A to Z. Give us a call today to schedule a free consultation.