Flat roofing is often thought of as leaky and unreliable, but new innovations in materials and installation techniques mean they are not only more reliable, but also longer-lasting and affordable. Commonly found on extensions, garages and commercial buildings there are two types of flat roof:
Warm roofs – are best for homes; a layer of insulation is laid above the roof deck with weatherproofing placed on top, which keeps the roof surface warm.
Cold roofs – have insulation on the inside of the roof and a waterproof layer installed directly onto the roof deck. Ventilation is required in cold roofs.
Flat roof materials
Flat roofs were traditionally made of felt, which could degrade easily. New single-ply waterproof membranes made of rubber or plastics are much more durable and long-lasting. Flat roofs are made up of a number of layers:
Ø Roof deck – can be made of timber, composite, metal, concrete or plywood
Ø Vapour control layer (VCL) – this layer is necessary in warm roofs and should be applied between the deck and the insulation. The VCL is commonly made of polymeric foil, bitumen or a polyethylene membrane
Ø Waterproofing – modern flat roofs use single-ply membranes now rather than unreliable old techniques of layering felt and asphalt. New single-ply membranes are typically made of uPVC, elastomeric, rubber and thermoplastic
Ø Surface layer – a top layer, sometimes made of stone chippings, mineral or hard resin in applied as a protective layer
Green roofs
Green (or grass) roofs are a popular addition/alternative to flat roofing. The surface of the flat roof is covered with a layer of vegetation, plants, flowers or shrubs with a root resistant and drainage layer incorporated. A green roof is eco-friendly as it insulates and cools your home naturally as well as encouraging wildlife. The Green Roof Centre claims that installing a green roof doubles its lifespan and reduces its annual run off by at least 50%.
Regulations for flat roofs
Firstly, always check with your local authority to find out if you need planning permission to install a flat roof. This may be necessary if you live in a listed building or in a conservation area. There are a variety of building regulations you must adhere to when installing a flat roof – your roofing contractor will be aware of the latest regulations; some of which state:
Ø The flat roof must have a slope of 1:80
Ø Cold roofs must have ventilation
Ø Warm roofs should have a VCL applied to the roof deck
Ø Roofs should be strong enough to walk on and wind resistant
Ø Water should drain to one or two edges
Flat roof installation and maintenance
The Flat Roofing Alliance (FRA) recommend you inspect flat roofing twice a year; check for bare patches, puddles and make sure drainage is working and gutters aren’t blocked. To install your flat roof safely and competently hire a roofing contractor, preferably someone specialised in flat roofing. Get at least three quotes and check reference and insurance credentials before you hire. While not essential, you may like to hire someone who’s registered with a trade association such as the National Federation of Roofing Contractors (NFRC) or the FRA.
