Technical FAQs Technical FAQs

Technical FAQs for Installers

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What is EPDM?

EPDM (Ethylene Propylene Diene Monomer) is a type of synthetic rubber that is manufactured for all types of sealing products such as door seals and garden and household appliance hoses. In sheet format, EPDM’s properties make it the perfect material for flat roofing applications:

  • It repels all weather conditions.
  • It’s flexible and easily bends with no stress, which means a perfect fit.
  • It stretches, with up to 300% elongation, so allows for typical building movement.
  • Its performance isn’t affected by extremes of temperature, and is proven to be stable between -30°C and  +120°C.
  • It won’t tear, split or crack with age.

Are EPDM synthetic rubber roofing membranes new?

No, EPDM was first manufactured in America in the 1960s, and it has been used successfully as a roofing membrane for over 50 years.

What does ‘fleece reinforced EPDM’ mean?

DuoPly is a reinforced membranes – externally with a fleece layer. The majority of EPDM in the UK roofing market is non-reinforced and does not offer the same benefits as DuoPly.

As a DuoPly installer this means:

  • A thicker, better quality product than your competitors
  • It’s easier to install because reinforced membranes lay flatter
  • There is no requirement for base tie-ins or peel stops to control membrane shrinkage that occurs in non-reinforced membranes
  • Added toughness and durability for the benefit of your customers.

How long will a DuoPly fleece reinforced EPDM flat roof last for?

The DuoPly membrane carries a 20-year warranty. However, the evidence ­– from both laboratory tests and actual installations – suggests that, when correctly installed, a fleece reinforced EPDM roof will last in excess of 50 years.

What are the main benefits of using DuoPly fleece reinforced EPDM?

Distributed by A R Systems in the UK, DuoPly offers many benefits:

  • The options of the fastest, strongest and best looking EPDM systems to install
  • Proven to last for 50 years
  • Mechanical fix or adhered options
  • Cold applied adhesives – no fire hazard risk
  • DuoPly with Pre-Applied Seam Tapes (PST) minimises installation time and removes the need for labour intensive seam welding
  • DuoPly is available in 1.52m widths for ease of access on those awkward jobs.

What is PST?

Pre-Applied Seam Tape (PST) is an industry leading engineering breakthrough. It increases the safety, reliability, consistency and speed of application of installing field seams with DuoPly membranes. The increased strength and speed saves you time on every job.

If DuoPly fleece reinforced EPDM is so good, why isn’t everyone using it?

In the UK, EPDM roofing membranes are dramatically rising in popularity, with standard ‘naked’ EPDM being the normal product. As the demand for this type of roofing grows, so does the desire for stronger, thicker products. In countries where EPDM roofing has been around for a long time, the thinner EPDM membranes have been superseded by reinforced EPDMs due to their better qualities. The same trends have started to show now in the UK where the thinner types are now being used by the DIY enthusiast and the professional roofers use reinforced EPDMs. Fleece reinforced EPDMs are now available through A R Systems offering DuoPly EPDM roofing system.

I am a professional roofer, so why do I need training?

Regardless of material quality, a quality installation is essential. Although our fleece reinforced EPDM roofing system is among the simplest available, training is essential to ensure you fully understand the materials, their diverse uses and applications. And, ultimately, training will help to ensure total customer satisfaction – every time.

Is DuoPly fleece reinforced EPDM environmentally friendly?

EPDM is one of the most environmentally friendly materials used today in the construction industry; it is recommended by the International Kyoto Ecology agreement as the best value sustainable eco-sound roofing available.

The initial production of the membrane has a low embodied energy number (the amount of energy required to produce and implement a product from material extraction, manufacture, and installation). In addition, several other components, such as cleaners, primers and adhesives, were developed for use with the EPDM membrane to reduce VOC (Volatile Organic Compounds) emissions during installation.

Post-industrial products can be reincorporated (recycled) into the manufacturing of other roofing products and accessories, such as walkways and roofing tiles, so minimizing the impact on landfill.

Do you still need to use insulation with DuoPly fleece reinforced EPDM?

Despite its superior properties, fleece reinforced EPDM should still be used in conjunction with insulation. Building regulations can also mean insulation is compulsory. In April 2006 the revised Part L of the building regulations came into force, with the aim to reducing energy used in buildings. The key requirements are:

  • To reduce energy used in buildings by at least 20%
  • In most refurbishment instances additional thermal insulation is required to meet the required ‘U’ value. If such an upgrade is not technically or functionally feasible or would not achieve its pay back within 15 years

Do DuoPly EPDM have British Board of Agrement certificates?

Yes, it holds the coveted British Board of Agrement certificates, DuoPly (No. 11/4853).

What are the fire ratings for DuoPly?

The fire ratings range in accordance with the build up of the roof.

  • As stated in the BBA certificate No.02/3967 DuoPly® Fleece reinforced EPDM has rating of Ext FAA as per BBA certificate. This relates to the following roof construction of steel deck, vapour barrier, PIR/PUR insulation and DuoPly® Fleece reinforced.
    Tested in accordance with BS476 -3

The above build up is mainly for commercial type properties so the ratings would be misguiding for domestic type buildings. In 2005 we ran further tests on typical residential style roofs and the following ratings were achieved.

  • Ext FAC Typical warm roof construction; OSB deck, vapour barrier, insulation and DuoPly® Fleece Reinforced
  • Ext FBC Typical cold roof construction; OSB deck & DuoPly® Fleece Reinforced
    Test to BS476 – 3: 2004 External Fire Exposure test

Tester – Warrington Fire Research

EPDM Fire Ratings

A boundary is defined in the Building * Regulations as the boundary of land belonging to the building up to and including the centre line of any abutting street, canal or river.

(1) Not acceptable on any of the following buildings:

  1. Industrial, storage of other non-residential purposes group buildings of any size
  2. Houses in terraces of three or more houses
  3. Any other buildings with a cubic capacity of more than 1500m³.

(2) Acceptable on buildings not listed in Note 1, if part of the roof is no more than 3m² in area and is at least 1500mm from any similar part, with the roof between the parts covered with a material of limited combustibility.

  • To achieve EXT. FAA regardless of the substrate the membrane should be covered with smooth, shard-free pebbles.