Hello 

I am new here.

We have a moss problem on an old north facing slate roof, in an area of high rainfall, not far from the sea in the West Highlands of Scotland.  

There is no felt underneath the slates and the moss seems to be acting like a sponge sucking rain water back up onto the underlyling planks! The slates are held down with old steel nails. During the frequent storms quite a lot of salt spray seems to get to the house. In winter a lot of the wooden planking seems to be slightly to moderately damp (lots of buzzing when tested using a damp meter!), however it seems that the sea salt that has built up over time seems to be preserving the wood (!). 

I have no idea why the nails are not corroding faster, but mostly they seem fine so far.

We are thinking of adding a copper wire (or copper or sink flashing) near the top/apex of the roof, to help kill off the moss, however we are concerned that this might corrode 
a) The nails
b) The cast iron guttering & down pipes
c) The lead flashing

An alternative might be to poor some sort of chemicals along the top for the roof say once a year, however it is a pain in the ass to get onto the roof which is quite high and at a steep gradient.

Have any of you folks tried copper wires or strips, or zinc strips? If so
– How effective was it at killing moss
– How much do you need in order to be effective
– Did you have a problem with staining building up over the years?

With thanks

J

 

J