New and dry roof tiles are inorganic since all organic substances
are burned away during production. Tar is produced by the resin from
Even board is produced from wood and therefore tarred roofs are organic. The organic substances give nutrition to the moss' spores. The accretion has started. After a while dirt and damp gathers on the tiles which gives it organic qualities. The damp gives the moss further nutrition and the accretion increases. A regular accretion of moss.
To stop the affections the whole roof must be sanitized including the surface and the pores: spores and old remains must be totally disinfected which prohibits further affection.
Before you spray on Bensaltenside, all loose moss should be brushed away. You need less Bensaltenside if you do this.
Before the treatment you should put in strains in the guttering so the moss does not clog up the drainpipe after removal of the moss.