Weeds growing through flat roof in poor repair

Questions from potential buyers about the state of a property's roof are very common due to the high cost of repair. The time required to carry out roof repairs can also often mean serious disruption for new home owners.

Over the past few decades, bituminous felt roofs (often referred to as flat roofs) have become common for the simple reason that they are cheap. The felt is supplied on a roll, and consists of layers of fibre (glass, organic and at one stage asbestos), which is compressed into a sheet with a bitumen compound. Asphalt is also common, albeit more expensive than felt.

The lifespan of these roof types is anywhere between 20 and 40 years - depending on the exposure to sunlight and other elements. The quality of workmanship is also a factor affecting how fast a roof deteriorates, and unfortunately, poor attempts at repairs or maintenance can accelerate the decline of a roof. In severe cases, amateurish roof repairs can result in severe issues such as damp being hidden and untreated.

During a home survey, surveyors will be looking out for cracks in the surface of the roof.

In the case of this property, the roof was covered with felt with gravel laid over the top. Weeds had got a foothold in the cracks, and their roots worked had through the cracks to allow moisture to penetrate. Generally the roof covering was in very poor condition, at the end of its life. The two extensions made to the property were of timber frame construction, also with flat roofs covered in felt, and also were both at the end of their useful life. Armed with this information, the buyer was able to negotiate a reduction in the purchase price to account for the extensive and much needed repairs.

A recent trend has been to use flat roofs as roof terraces. Care should be given to avoid compromising the felt layer, as indentations from chair legs, plant pots and even heeled shoes can seriously damage a roof. Buyers should be aware of this when considering a property with a roof terrace, and may wish to request that the surveyor consider this point particularly when carrying out the property survey.