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How to Identify Genuine Onduline Roofing Sheets

How to Identify Genuine Onduline Roofing Sheets
By Roofing Megastore Team 7 months ago 660 Views No comments

Onduline is an incredible, high performance, lightweight and durable bitumen roofing sheet that comes with the option of some clever underlay systems.
It’s long lasting, versatile and suitable for many different roof types such as shed roofs, garages, stables, kennels and farm buildings.
It’s extremely durable, will withstand many different weather conditions and comes with a 15-year guarantee. *

But, in 2017 there was the introduction of some replica Onduline products that unfortunately don’t offer the same qualities, flexibility or guarantees. Those replicas are still being sold today and it’s sometimes hard to spot the real Onduline from the replica.


In this article we cover how to identify if you are buying Onduline or one of its competitors.

You may find that it’s not always clearly marked what kind of bitumen roofing sheet you are buying but there’s a number of differences that you can look out for.

Favoured among many, Onduline is the only manufacturer to produce a single layer mono thickness sheet whereas its competitors tend to have multiple layers. The single layer gives it enhanced strength and much more sheet rigidity, making it more resistant to bending, tearing and shock.

BTM multi-layer sheets are often sold in Onduline’s place and are made up of three or more sheets and have a lower bitumen infusion making them weaker. When picking up BTM sheets you can sometimes spot this as there may be damage at the edges of BTM displaying the multiple layers, this can often happen when they’ve been loaded on top of each other. Another sign that you might spot is that the edges of BTM sheets aren’t cut as neatly and may be showing signs of curling.

Onduline sheets, on close inspection, look different to its competitors, it will have a tighter pattern on the top of the sheet and on the underside of the sheet the pattern is less tight but still more prominent than on a BTM sheet

Sometimes you’ll find the Onduline trademark embossed on their sheets and you’ll always find their quality control production information on the last corrugation, this is an easy give away sign to look out for.

Another quick and easy way of spotting the real Onduline from the replica is by looking at the thickness of the product, Onduline is 3mm thick, whereas a lot of its competitors are only 2.7 or 2.6mm thick.

Why is it so important to make sure that you purchase Onduline?

Now that you know the main signs to look out for, here’s a bit more information on why it pays to do a quick double check to make sure that what you are buying is Onduline.

Onduline is manufactured from organic bitumen roof fibres and is extremely tough, it’s resistant to driving wind, rain, hail and snow and guaranteed to be waterproof for 15years. * Unfortunately, a lot of its competitors don’t hold the same guarantee and sometimes can only guarantee the product for as short as two years. A guarantee offering longevity is important for a roofing material.

Onduline is bought in sheets of 2m (L) by 950mm (W) however, they are a different size and have a different corrugation profile and weight than its replicas.
BTM sheets tend to be smaller in size with a smaller corrugation profile and are also lighter and not as strong as Onduline. Because of this it’s not possible to use a combination of Onduline and BTM multi-layer sheets on the same project.
Because of their different weights and thicknesses, they will need different fixtures and fittings. Using a cross of fixings and fittings with the different sheets could result in the BBA Product Certification and any other certification being invalidated.


Tests have been carried out to measure the longevity and weather resistance of both Onduline and BTM multi-layer sheets

Using forced weather conditions both sheets were exposed to equal levels of light radiation and water sprays in an QSUN 3000h accelerated aging apparatus.

The BTM sheet experienced degradation showing exposed cellulosic fibres and severe fading effects. Whereas Onduline maintained its colour better with little discolouration and it had minimal cellulous fibres exposed.

In addition the BTM sheet showed 20% more sheet deformation and sagging when compared to Onduline and the BTM sheet absorbed a much higher amount of water.

More benefits of Onduline roofing sheets:

Onduline’s manufacture process involves inorganic pigments and resin being applied to the base sheet before bitumen impregnation which results in a much longer colour retention.

Onduline sheets also come with a variety of different accessories available to purchase which enhance their weathering characteristics and make installation even quicker and easier. And, they are the only sheets that can be used with their patented Ondutile tile underlay system to create an independent secondary weatherproof roof.

If you are starting a project and need to purchase some bitumen roofing sheets you will be able to find a great range of Onduline roofing sheets available at Roofing Megastore. If you are still concerned as to which roofing sheet to buy for your project give our friendly customer services team a call on 01295 565565, send them an email at [email protected] or chat to them online.

*when installed to the manufacturer’s guidelines

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