When we moved into our home last August, our surveyor recommended fitting a chimney cowl to prevent rainwater ingress, and specifically recommended a rotorvent cowl as the best type.
We had one fitted, but it is silver and reflects the light into my neighbour's upstairs hallway. He is finding this disturbing and has offered to contribute to the cost of a solution.
I am thinking of simply replacing it with a matt black rotorvent cowl so that less light is reflected. Does anyone have one? If so, can you confirm that they give minimal light reflection?