This is a 6 flue stack and you can see the brick withes that separate each flue. One of the flues is serving a boiler and the old terminal is visible. One other flue is serving a wood burning stove and the other 4 flues are unused. You will notice in the finished photo that the unused flues are protected by vent caps which keep the rain and birds out and but keeps the air circulating through the flue and reduces the risk of further damp building up. The lower end of each unused flue will also be ventilated.
The client did not want to take the whole stack down because of the cost and uncertainty of the cause of the damp. We suggested a compromise solution to take the stack down to a stable base, in this case 9 courses of brick work, and then rebuild but to incorporate a lead tray at that height to reduce the risk of water penetrating into the building.
The stack was rebuilt to its original dimensions using a lime mortar which in time will be a close match to the old mortar.
It is worth noticing the flaunching on the top of the stack and that it is set at a steep pitch to encourage rainwater away and the corbelled courses creating a “drip” to also encourage the water away. If you look closely you will also see the weep holes sitting above the lead tray and which will allow the water, including any running down the inside of the flue, to run away from the interior of the building.
The lower part of the stack is still vulnerable but the stack is now stable and the repairs will make a significant difference to its weather tightness.
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