I am building an extension and the roof will only have an 18 degree pitch. The house has existing Rosemary tiles 100 years old. I am told I cannot use these as they will not suit a fairly flat roof. Can anyone suggest tiles similar that will ? Thanks.
The roof is too flat to be tiled.
However, I can understand your wanting it to match in.
The solution is to cover the building with waterproof marine ply nailed and glued, cover that with waterproof plastic membrane with sealed edges, then double batten, to enable the rain water that will blow through the tiles to run away, then tile.