Moss Growth – ‘vegetation’ or ‘deposits’ can appear on the surface of a roof in many forms and the type of vegetation or deposit will be determined by a number of different factors. Typical terms used to describe these are lichen, algae, fungus or moss growth. Limited presence or absence of sunlight on a roof surface is often an influencing factor in the amount of moss or lichen growth. Usually there will be less growth if there is regular sunlight, so consequently when there are shady and cool/moist conditions, the presence of moss/lichen growth is more likely.
Therefore moss/lichen growth on as roof surface may look innocent enough however it can be seen from the information above that it can be quite problematic if it is not dealt with. Caution should be taken when removing moss/lichen deposits from a roof from a personal safety perspective (particularly safe access), as well as the method adopted to remove any deposits. After all it would be pointless clearing the deposits and then damaging the roof surface in the process. The use of a high pressure water jet for example will damage certain types of roof tiles so always carry out some research before deciding on which method to use.
Things to look for include evidence of temporary repairs around flashings including the use of ‘flashband’, which is basically a bitumous tape. The use of flashband should never be considered as a permanent solution and in fact it will not be long before moisture ingress starts to re-occur unless a more substantial repair is not carried out quickly. To a Surveyor, flashband screams out problem!
A Surveyor will also commonly see problems associated with roof flashings which are a result of poor workmanship. The reasons for poor workmanship are wide but will include cutting corners to save money, use of inappropriate materials, lack of knowledge and understanding, ‘getting the job done quickly’, if it’s out of sight, it’s out of mind’ etc. I used to think I’d seen it all however there was always something new just around the corner that I had not seen before! Whatever the reason, poor workmanship creates a lot of problems in buildings and something that I am sure will continue to do so in the future. The photographs below provide some examples of poor workmanship of roof flashings.
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