The growth of moss on a tiled roof is a fairly common occurrence, and one that is often disregarded by homeowners and landlords who believe that this ordinary plant is unlikely to cause any lasting damage to their property.
However, the truth is that moss, which has a habit of growing quickly, can cause irreparable damage to tiles that could, in turn, lead to serious problems with the structure of the roof itself. For this reason, the presence of moss on a roof should never be ignored.
You’re most likely to notice moss growing on the north-facing side of a roof, where there is the least exposure to the sun. This means the tiles are more prone to remaining damper and cooler for longer after rain, which are ideal conditions for moss to grow rapidly. However, moss may also accumulate in other shady places, such as under trees or in the shadows of neighbouring buildings.
Moss that is left to grow on a roof acts like a sponge during the rain, absorbing large quantities of water, instead of allowing it to run off into the gutters. This exposes the tiles to long periods of saturation, while in colder weather frost and ice can form over the tiles and cause them to deteriorate. Cracks in the roof tiles, caused by prolonged soaking and exposure to ice, will lead to rainwater seeping into the roof structure, potentially causing damage to the wooden components that could mean more extensive roof repairs are needed in future.
Moss can be removed with a stiff brush, though obviously there are implications about how to perform this safely at a height. Chemicals can also be purchased to help to prevent the growth of moss in the future, but it is important that the tiles are in sound condition before this is applied.
However, a professional inspection of your roof by a roofing company may be a sensible precaution to take to ensure that there is no damage to the tiles that could lead to more serious problems. If any defects are discovered, which may not be apparent to the untrained eye, they can be swiftly resolved, thus keeping the extent and cost of repairs down.