wrote in message
oups.com...
Yes I agree. The felt roof that I am about to replace has been on since
I bought the house in 1986. It never had stones on - but rather a
'silver' coloured rubberised coating - any idea what that may be?

It's a reflective layer to reflect the sun's radiation / UV.
But the way, what are the stones for that you sometimes see ?
They just mean the roof gets punctured when you walk on it.

Two reasons:
Reflect the UV radiation from the bitumen/felt to prevent degradation

and
Increase the surface area for the evaporation of rain water

You shouldn't puncture the roof because you shouldn't be walking on it!

If you want to walk on the roof then you should use solar reflective paint
or a resinous compound top coat.

Dave