Moss

The jury remains out on the subject of moss, It has certainly increased on thatch in the eastern counties during the last twenty years. My believe is that with there being little or no heavy industry in the midlands now and with the wind normally westerly the air in the East is much cleaner and moss and lichens thrive more abundantly.

New thatch in general does not suffer from moss for around eight to ten years. Northly facing elevations always seem to suffer first and worst. Valleys with their increased water flow will tend to suffer as do chimney aprons. Then the moss spreads to the shaded areas.

On some thatch areas lichens will take hold on closer inspection they look like little trumpets standing on the roof.

Although there is little you can do, any overhanging shrubs or climbers should be kept under control. Over hanging braches from larger trees should be kept clear as possible. Seek professional advice on larger trees as if they are in the curtilage of a listed building, consent may be required.

Normal re-ridge and repair maintenance will clean and remove moss although once established it will return.

Some firms knock at the door and offer to remove moss this is invariably a waste of money and in general they are cowboy operators who will find more work on your roof when they have started so the original cost is multiplied in some case by many times.

As far as I know there is no chemical licensed to be used on roofs so application may well be illegal.