Two pieces of work on one old Warrington roof: the chimney cow re-bedded and the crown renewed in fresh mortar, and the mossy, failing bedding along the ridge line raked out and re-pointed.
This is an older property on the edge of Warrington with a heavy grey slate roof and two brick stacks, and both jobs on it came down to the same thing: mortar that had given up. Moss was growing out of the joints along the ridge and out of the top courses of the chimney, which only happens once the mortar has gone soft enough to hold water and hold roots.
We took the stack first and the ridge second. The two are connected in practice — a failed bedding at either lets wind and water under the tiles and into the roof structure, and on a long exposed ridge like this one the wind does as much damage as the rain. Both fall under our chimney repair work.
Before touching anything we went over the stack for the usual faults: cracked, crumbling or missing mortar between the courses, pots or cowl fittings sitting loose or out of line, staining on the timbers or in the loft below, and damage to the lead flashings and soakers where the stack passes through the slates. The close-up photograph shows what we were dealing with — a thick crown of old cement broken down to a sandy, crumbling mass with the pot leaning in it.
The old mortar was raked out back to sound material, then fresh weather-resistant mortar was worked in and the crown rebuilt round the base of the pot. The cow was realigned as it was re-bedded and finished with a cowl on top, and the flashings were sealed where they meet the brickwork. The finished crown in the photographs is shaped to a slope on all four sides so nothing stands on it.
The ridge on this roof runs a long way, and the photographs taken before we started show cushions of moss growing along the full length of it, both between the ridge tiles and in the joint where they sit down onto the slates. Behind that moss there was very little mortar left.
The failing mortar was removed along the ridge line and the alignment and condition of each tile was checked as we went, because there is no sense pointing round a tile that has shifted. The ridge was then pointed up in fresh mortar. The last photograph shows the result — a clean buff line running the length of the roof above the old grey slates, with the joints closed and the moss gone.
A ridge that has lost its bedding is not just untidy. The joint is what stops wind driving up under the top course of slates, and once it is open the water follows the wind into the structure, where it works on the timber long before anybody sees a mark on a ceiling. The same is true of a stack whose crown has broken up.
Old roofs like this one are worth keeping rather than replacing, and pointing is a large part of how that is done. We cover this and other chimney repairs in Warrington, and if your stack or ridge has moss growing out of the joints you can ask us for a free quote.
Tell us what the roof is doing and roughly where you are. We will come and look, and you get a written price before anything starts.
