Clay Tiles + Moss = Disaster

Have you ever had a clay or terracotta plant pot in your garden and used "feet" to raise it off the ground? You will probably know that if you leave your pot in direct contact with the ground it will crack during the cold winter months.

That is exactly what can happen to clay roof tiles

Moisture is the problem here, when it freezes during winter months it will expand and create a crack. That is not so much of a problem with clay pots as they are not too expensive. Clay roof tiles however are.

Moss growth on any roof will soak up any rainwater and retain it on the roof until it evaporates. In summer that can happen very quickly but in winter it can take days or even weeks for the roof to dry.

While the clay roof tiles are retaining water they are at risk from frost attack. This doesn't affect concrete or slate tiles so much as they are generally more resistant to freezing water.

Some roofing companies will recommend a protective coating or sealant that will prevent water ingress into the clay tiles. While these products do generally work they are often very expensive and have a limited life (ten years if you are lucky).

A simple, cost effective solution is to remove the roof moss and apply a moss killer chemical to prevent early re growth. With the moss removed the rainwater will drain into the gutters much quicker and the clay tiles will then dry out sooner and thus be less likely to suffer from frost cracking.

Below you can find some useful hints and tips:

• Frost can damage any tile but mostly affects clay tiles
• Shallow roofs suffer this type of damage more than steep roofs
• You do not need to remove roof moss with a pressure washer!
• Use a scraper or stiff broom attached to a long pole to remove excess moss
• Use a moss killer and not a roof coating to prevent moss growth
• Read up on how to use natural copper to prevent moss growth

Here you will find lots more information specific to roof coatings.

If you are thinking of removing the moss yourself or getting someone in I strongly urge you to wait until the roof is dry. I mean really bone dry. The moss will be so much easier to remove with a long reach pole as described above, In fact it will simply fall off!.

Avoid trying to remove wet or damp moss, you will find it to be very sticky and will easily turn to sludge making it very difficult to remove.