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Single Ply Roofing vs Felt Roofing

Single Ply Roofing vs Felt Roofing

A lot of people ask what the difference is between felt roofing and single ply roofing and what would benefit their property more. The answer to this question depends on several factors and an experienced roofer should always be able to advise you what would be best in your circumstances.

Here at Invictus Roofing we offer both Torch on Felt Roofing and Single Ply Roofing, both are strong and durable materials with very different appearances and application methods. Most modern flat roofs have a lifespan of 20 years or more, and Invictus Roofing offer 20 years insurance backed manufacturer warranties on all new and refurbishment flat roofing as standard.

FELT ROOF

This type of flat roof still has a bad reputation with some people, but I’m going to tell you why that perception is out of date. Most people have in mind the old ‘pour and roll’ felts of yesteryear, and these were thin bitumen felts glued together with a hot liquid bitumen between each layer. They had minimum internal reinforcing, with some containing natural hessian fibres which were prone to rotting. This type of felt, sometimes known as felt paper or tar paper, would effectively dry out and crack with age or UV damage from the sun. 10 years was pretty much the life expectancy.

MODERN TORCH ON FELT ROOF

Torch on felt roofing, in case you hadn’t guessed describes the method of application. Do not confuse these modern roofing felts with the older pour and roll system. Great strides continue to be made in bitumen and modified bitumen technology such as SBS or APP, resulting in much better resistance to UV damage and cracking.  This type of felt roof comes on rolls and is laid with the aid of a very large blow torch that heats and melts the rear of the felt, melting it onto the roof structure below. Typically it’s applied as a 3 layer system usually consisting of a perforated underlay, a 2mm underlay layer, then thick 4-5mm felt. These layers are all laid in a half lap manner, so all the joints are the furthest away they can be from another joint.

The thickest top layer is often a coloured mineral finish known as a cap sheet, and they are available in a variety of colours, as well as a plain felt finished with a silver solar reflective UV finish. All of these felt layers are also reinforced with strong polyester weave sandwiched in the middle of the felt, giving them incredible strength. In lifespan terms, I don’t know a single roofer that will not be happy to guarantee 10 years, because they know it will last 20, sometimes 30+. Invictus Roofing guarantees for 20 years. Not as bad as you thought is it?

1. Felt roofing is affected by UV rays, and it expands and contracts. This again over time causes weak points where water could enter.
2. Laps and joints around the roof edges are difficult to fully secure with felt roofing. This could allow lifting and damaging by the wind, and could leave weak points where the rain can get in.
3. If you’ve ever handled roofing felt you’ll know that it’s a relatively delicate material that could easily be damaged and breached, even during installation. This makes any cleaning and maintenance an extra difficult job too.
4. That being said, felt roofs do still need annual maintenance, clearing outlets and gutters and making sure they are in perfect working order. It is best to ask a roofer to carry this out for you.

SINGLE PLY ROOFING

What is a single ply membrane? In short any roof covering that can make a flat roof waterproof in one layer, unlike roofing felt with its 3 layer system for instance. This can include EPDM rubber and fibreglass, PVC , TPO, TPE and PIB.

Firstly these membranes generally share some desirable traits. They are lightweight, flexible, resistant to UV and micro organisms, handle extreme weather and temperature changes, fire resistant and self extinguishing, show good chemical resistance, are more aesthetically pleasing (compared to torch on felt) and can be very environmentally friendly. This has made these types of roof very popular on commercial premises and with architects as you can imagine.

1. It is vapour permeable so it will not blister, and it does not expand or contract with weather conditions. This means that cracks and weak spots don’t have a chance to form.
2. It is a very strong, stable waterproof material that is highly resistant to UV rays, and typical British weather conditions. Once again, this means that the integrity of the roof surface is preserved.
3. It has been widely used over many years for commercial roofing because office blocks and warehouses need maintenance free roofs that will last a very long time. Just think of how well this material could work for your home roof!
4. All laps and joints are permanently welded, the roofing membrane is secured to the roof structure, the storm resistant roof edges are fusion welded, and mechanically fixed, and the wall joint won’t crack or fall out like mortar, lead or sealant. This means that the roof can be totally secured against wind and weather, and the traditional weak points of the roof can be just as strong and secure as any other area of it.
5. At the end of its long life – typically in excess of 30 years – the material is recyclable, so single ply roofing is the right choice for our environment as well as your home.

A QUICK SUMMERY

Felt roof – Positives – low cost, proven results, suits roofs of any size – Negatives – not suitable for regular foot fall, requires heat to install, not DIY friendly, suffers from a poor reputation from older systems.

Single ply membrane like PVC, TPO, TPE, & PIB – Positives – lightweight, flexible, pleasant to look at, handles slopes and large areas, fairly durable, can be designed to mimick lead roofing (without the risk of theft) and fire resistant – Negatives – Costs more to install than other flat roof systems in a domestic setting, may not suit regular footfall, or complex details.

What ever the choice of roofing material, it is always important to ask a professional roofing service to assess your roof and help you decide on what would benefit your home/project best. Flat Roofing should ALWAYS be conducted by a trained professional registered with the NFRC (National Federation of Roofing Contractors). You can search registered roofers on the NFRC website.

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