I have three flues in my chimney. Two are active and go to a stove and a fireplace. The third flue goes to the bathroom. Now I am going to build a wall 5 mm from the chimney breast in the bathroom. The plan is to seal off the flue that goes to the bathroom. It feels unsafe to have a 15x15 cm opening behind a tiled wall. There I will not have any possibility for closer inspection or action. I think there is a risk of bird nests, moisture, etc.
My initial thought was to seal the hole in the living area and pour a few liters of loose concrete into the flue.
Now I am considering instead filling the flue with stone wool and then gluing/screwing a metal sheet onto the chimney cap.
Thoughts?
