Most flat roofs consist of a timber decking nailed to the roof joists and covered with three layers of roofing felt which in turn can be strengthened using a layer of proprietary chipping compound, such as limestone, gravel or granite. The idea is for the surface to reflect rather than absorb sunlight, so helping to protect the felt.
Materials that cover flat roofs should allow the water to run off freely from a very slight inclination.
Modern flat roofs tend to use a continuous membrane covering which can better resist pools of standing water. These membranes are applied as a continuous sheet where possible, though sealants and adhesives are available to allow for bonding multiple sheets and dealing with structures penetrating the roof surface. Far more expensive flat roof options include sealed metal roofs using copper or tin. These are soldered interlocking systems of metal panels.
Flat roofs have a major weakness in that subsequent works done to them can produce a crack or puncture in the surface leading to leaks. Inside a property, water staining on the ceiling will indicate dampness getting through as felt coverings can deteriate with age and become porous. The roof surface will become uneven, buckling or cracking in some areas and on a particularly wet day,there could be drips of water seeping through the surface. Inspecting the ceiling after a prolonged period of rain is a good idea as the source of a leak is easier to trace. t is useful to inspect the ceiling after a long period of rain, as the source of a leak is easier to trace. It is also useful to trace the source of any staining as the leak may not be immediately overhead as water can penetrate the roof surface and travel between the roof and ceiling level before finding its way through the ceiling.
Inspecting the roof from the exterior can be done at ground level by checking the apron, which is the area where the edge of the front of the roof does not meet a wall. This is where strips of strips of felt are secured over facia boards, sealing the edges of the roof. A change to the colour of a section means it could be newly exposed and unweathered.
If a ladder is required to inspect the roof, it needs to be set up correctly and this is where the legislation concerning working at heights needs to be adhered to. If the roof shows signs of dips or puddles it could be due to the deck or the structural joists having deteriorated or perished. Scaffold boards can used to spread a persons weight across the roof if necessary.
Regular patch repairs means that either the whole roof or sements of it need replacing.