Rainwater

Shouldnt do but wouldnt want to drink it. nowadays all asbestos frowned on but the real harmful stuff was blue asbestos as it powdered easily and therefore easily inhaled.Your roof should have stabilised years ago.

Thank you.....When referred to as BLUE- I assume that's its colour??

Well not strictly it was a white powdery fibre that when seen through light in large quantities had a blue haze.Been banned for many years and predominantly used in insulating materials for walls.Sorry I am digressing here but your garage roof will not be made of this.Asbestos was a high risk for those working with it in powdered form .

Thanks -that was reassuring....