In my last article I provided a brief summary of typical UK flat roof construction together with an explanation of different roof coverings. As a result of the design/form of a flat roof they are often more vulnerable than pitched (angled) roofs to problems due to their reduced ability to discharge rain and other surface water adequately. A well constructed and properly maintained flat roof should remain in serviceable use for approximately 15 – 20 years. Life expectancy can vary depending on a number of different factors however if not regularly inspected and maintained there are numerous problems that can occur. Below I will discuss a number of typical problems that can be found when inspecting a flat roof and how these can be identified.
You do not need to be a surveyor or have any detailed knowledge of property or construction to realise that there are clearly issues with the flat roof shown in the images below. Some of these images show us the extent that people will sometimes go to carry out temporary ‘repairs’, when it is clear that there is a much bigger problem.
Water Ponding – Water ponding can occur on a flat roof for a number of different reasons, for example the roof was not designed or constructed correctly in the first place and is not allowing water into guttering our outlets, there could be impact damage (possible people walking across) or heavy loadings such as plant or materials that have resulted in ‘depressions’ in the roof, outlets or guttering could be blocked etc. In any event prolonged standing water on a flat roof can result in degradation of felt, stress and failure of joints, increased risk of condensation (as the internal roof surface temperature is reduced), and the build-up of moss and lichen. Standing water will also freeze in sub-zero temperatures, further increasing the possibility of condensation as well as becoming a health & safety risk if there is a need to gain access to the roof at that time.
|Source: Google Images|
Simple regular maintenance such as clearing gutters and outlets will help to reduce water ponding however this is something that is often overlooked by many property owners/occupiers. This is likely to be because many flat roofs are out of sight (and therefore out of mind!) and unless the roof starts to exhibit problems many will choose to ignore it. Water ponding problems as a result of poor design or poor workmanship are often more problematic to deal with and consequently more expensive. Again, many people will choose to live with these problems until of course the roof starts leaking and causing consequential damage to other parts of a building.
Other issues such as de-bonding at up-stands can also be encountered by a surveyor during an inspection of a built up felt flat roof as well as numerous other problems that occur as a result of poor workmanship. In my next article I will discuss problems associated with mastic asphalt flat roofs, where some similar issues to those described above will be explored together with some other problems that may occur as a result of using a different material.
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