What is moss on the roof a sign of?


We often visit our customers following reports of damp in the loft space, or in the upper rooms of the building. While sometimes you will not see any signs that there is an issue. There is one little telltale sign that there is something not quite right with your roof. Moss.

Why is moss an issue on my roof?

Moss is often found in environments that are damp and shaded, whilst you might be thinking that the roof should be clear as it is not shaded, it doesn’t mean that the roots of the moss aren’t shaded, or parts of your roof might be covered by trees and foliage. The moss absorbs the damp to help bed in its roots. Where these roots have round a gap between the roof tiles, they can start to become strong enough to lift tiles and shingles. Fed by rain, these roots can grow at an alarming rate and moving these tiles can lead to further mould and damp underneath. All of these issues can lead to holes in your roof which can allow rain to enter your home.

How immediately should I take action?

Many roofs can survive well with so much moss for long periods of time, sometimes even many years. However, we do recommend you do something about it before issues do arise. There are a number of ways to remove the moss yourself, but please take extra care, as moss and mould can leave your roof extremely slippery to work on/with.
Firstly you can use a standard garden hose and a scraper/brush to ease the moss out of the crevices. Please do not use a pressure washer as this can cause more damage when not done by a trained professional.
There are a number of moss specific treatments that are available, with the most common being a powder. While these treatments will cause very little to no damage to your actual roof, they can be harmful to vegetation and wildlife, so should only be used in completely necessary and with great care. Please also take note of the environmental factors around you, particularly with aquatic areas, including streams and lakes as can cause a significant issue if it enters the water.

Moss prevention

There are a few things you can do to help moss prevention, whether you have previously had a moss issue or you would just like to avoid it becoming an issue in the future.

  • Removing all overhanging tree branches can greatly reduce the risk, as these can promote damp shaded areas.
  • Remove stuck or continuous debris from the roof. While many leaves and sticks will work their way off within a day or two, we find that some try and stick around a little longer. Try to help these work their way off.
  • Keep your gutters clear. Moss can also build up in your gutters, leaving them clogged and with plenty for leaves to cling onto.
  • Zinc Strips. This is one of the safest methods to prevent future growth of moss. Nail zinc strips along the ridge caps along the peak of the roof. When it rains, zinc is released onto the roof and powerfully inhibits moss growth. Zinc strips usually last for 1 year and work best if started in a moss-free environment.

If you are unsure about the moss on your roof, or would like a professional to take a further look, please contact a member of our expert team today.