From the first introduction of Battery/System Garages the preferred material was corrigated asbestos. When the health problems associated with this material were realised the material of choice switched to fibre cement although corrigated metal sheeting was used in some cases.
Both asbestos and fibre cement are porous and the build up of moss and other vegitation can take hold. by holding water on the roof longer then the roof material starts to break down and water seeps in. The dark part of the under roof photo shows where this is happening:
Unless the garages have been re-roofed in the last 15-20 years they will have asbestos roof sheets. These need to be removed. The cost of this work continues to rise and the number of sites that will take asbestos is deminishing hence higher prices are on the way. It is already against the law to sell a house that contains asbestos and this could include outbuildings and garages before long.
Fibre cement was the material that most people turned to when asbestos was outlawed. However both attract organic growth.
Gutters are important too and the original Marley’s had accessible gutters although they proved to be a bit too narrow and needed cleaning out quite often.
With System B the problem is much the same.
