Flat Roof Systems Compared

As experts in both the Evalon Polymeric and Everlast GRP Fibreglass systems, Everlast continue to offer the superior solution for any application.

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Performance Demands	Evalon	GRP	EPDM Rubber	Bitumen Felt
Durability	The Evalon System is independently certified by the British Board Of Agrement to last in excess of 30 years. Galavanised steel edge trims coated in Evalon, easily withstand ladders etc.	Glass Reinforced Plastic (Fibreglass) is extremely tough (hard) at the expense of flexibility.	Different grades and qualities available. Most systems sold to untrained installers. Edge trims formed by wrapping rubber around pieces of wooden batten.	Bitumen roofing pre-dates the Romans. Succeptible to damage from summer sun and winter frost alike. Edges formed in felt, high failure rate.
Seam Integrity /Strength	Evalon is fusion welded to form a single monolithic membrane where lap joints are fused together to form a double layer which is even stronger than the main membrane. Remains 'weldable' for entire life making alterations etc simple.	The main advantage with GRP, seamless and jointless.	Requires solvent adhered (glued) joints around details, wall flashings, pipe penetrations etc. Easily contaminated during installation - the most common cause of EPDM failure. EPDM 'cures' after installation, becoming stiffer, hard to join/repair.	Hot melted joints - can become soft in sun, and brittle in cold. Unreliable at best.
UV Sunlight & Heat Resistance	Evalon's UV resistance and heat reflection is so good that it's widely specified in black. Does not 'cure' over time, remains flexible and weldable indefinately.	GRP is highly resistant to UV and can be specified in almost any colour.	EPDM is resistant to UV radiation and heat.	UV exposure breaks down and extracts oils and bitumen from asphalt, eventually it becomes brittle and cracks. Temperature can fall quickly on clear nights causing felt to contract, often tearing/splitting.
Reaction to Fire	Evalon is self-extinguishing and complies with all regulations for fire resistance.	GRP has some fire resisting properties.	Some EPDM roofing membranes exhibit combustible characteristics.	Poor fire resistance. Built-Up Roofing Systems require aggregates and fire retardant coatings to provide retardancy.
Vapour Transmission /Condensation	Evalon promotes vapour transmission, greatly reducing the likelihood of condensation problems occuring.	GRP does not allow vapour transmission, The risk of condensation leading to damp can be higher with GRP, particularly over bathrooms and kitchens.	EPDM allows limited vapour transmission.	Felt allows vapour transmission reducing the risk of condensation.
Elongation/ Flexibility. Expansion/ Contraction	In independent testing Evalon was stretched to 300% it's normal length without failure. Significant building expansion and/or contraction is easily accomodated.	GRP is not designed to be capable of any measurable elongation or movement, but will withstand normal building movement through expansion and/or contraction.	EPDM is highly flexible and can cope with building movement.	Felt is not capable of substantial elongation without failure.
Appearance	Sleek clean appearance, extremely moss resistant. Immitiation standing seam and lead roll profiles available. A wide range of colours available including; slate grey, lead grey, copper, black, white.	Clean, seamless, but "plastic" in appearance. Can become mossy quickly, especially from existing gutters. Can be top coated in most colours.	Rubbery, only available in black, looks dark grey (unless painted white), can fade.	Can look reasonable when new, quickly becomes tatty, cracked, blistered. Stone aggregate ballast washes in to gutters causing blockages and plant life growth.
Installation	German produced membrane is mechnaically fixed and/or bonded to roof before being fusion welded allowing clean, safe, reliable installation in most weather conditions, without the use of flames or smelly/flammable solvents.	Produced on site using polyester resin, glass fibre and rollers etc, can be messy, should only be attempted in totally dry weather at temperatures between 5 and 25 degrees. Very strong odour from styrene used in polyester resin, which is also highly flammable.	Quite simple to install, when properly trained. Requires glued/taped joints, easily contaminated with dirt, moisture and/or old bitumen during installation, leading to early failure.	Applied by gas torch or bitumen boiler, high risk of fire and very expensive insurance premiums.