The Disadvantages of EPDM roofing

Installing on an awkward roof shape

 

The main disadvantage of EPDM lies in the type of roof you’re installing it on.

If your roof is a simple, flat, rectangular shape, EPDM is usually straightforward to install and performs extremely well. However, if your roof has multiple angles, skylights, vents, pipes, or other protrusions, installation becomes much more complex.

EPDM is supplied in large, flat sheets designed to cover simple, uninterrupted surfaces. On a standard roof, this works perfectly — but on an irregularly shaped roof, it can be difficult to lay the membrane smoothly without cutting and joining multiple sections.

Even if installed carefully, edges and corners may remain exposed, allowing moisture to seep underneath and potentially cause long-term damage to the roof structure. For this reason, EPDM isn’t always the best choice for roofs with an awkward layout or lots of obstacles in the way.

 

I Have an Awkward Roof Shape — What’s Best for Me?

If your roof has an unusual shape or includes several details such as skylights and vents, Liquid PU or GRP roofing are often the better option. However, if you prefer EPDM rubber, there’s also the option of RESITRIX, a hybrid EPDM system, which comes in rolls and is hot air welded.

1. Liquid PU Roofing

Liquid PU roofing is applied as a liquid coating that cures into a seamless, flexible membrane.

It can be brushedor rolled directly onto the roof surface, making it ideal for complex shapes and details. Because it forms a single, continuous layer, there are no seams or joints for water to get through.

2. GRP Roofing

GRP (Glass Reinforced Plastic) roofing is installed in layers using resin and fibreglass matting to create a tough, seamless surface. This can be moulded around edges, corners, and protrusions with ease for a watertight finish.

3. RESITRIX SKW

RESITRIX SKW (Hybrid EPDM) is a bitumen-backed EPDM that is reinforced and hot air-welded. It comes in 1m rolls but can also be bought in 333mm, 500mm & 666mm. This system is ideal if you can’t work with larger sheets of EPDM rubber.

Aesthetics

While this doesn’t affect the performance of your roof, we understand that appearance matters, especially if your flat roof is visible from windows or higher ground.

One of the main aesthetic drawbacks of EPDM roofing is its limited colour choice. The membrane is typically available only in black or slate grey, which gives it a clean and modern look but doesn’t offer much room for customisation.

That said, most EPDM installations are bordered with trims, and you can usually choose from three trim colours: black, grey, or white. Since the trims are the most visible part of the roof from ground level, the membrane’s colour itself often isn’t noticeable unless you’re viewing the roof from above.

If you prefer a different colour, EPDM can be painted using acrylic paint to achieve a different finish. This allows you to match your roof to surrounding materials or create a lighter look; however, you would need to keep up with maintenance on this, as the coat will fade or peel due to UV exposure. It is important to contact the manufacturer if you plan on doing this, as adding anything outside of the system-compatible products may void guarantees or warranties of materials.