If you are having a chimney stack rebuilt near Honing and want to know exactly what should happen from the roofer's first visit through to the finished job, this page walks through every stage in order.
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Before any scaffolding goes up or any work is priced, a proper chimney inspection should be carried out. From ground level, a roofer will use binoculars to assess the overall condition of the stack - the pointing, the brickwork, the flaunching and the pot. If access to the roof is possible from a ladder, they may get a closer look at the flashing and the lower courses at this stage.
The inspection is not just about confirming whether a rebuild is needed. It is about establishing where the work needs to start and stop. A stack that looks bad from the outside may have problems running further down than the visible damage, and that affects both the price and the access required. A thorough initial look saves everyone time and prevents surprises mid-job.
At this stage the roofer should also check whether the flue is in use. An active flue has different capping and pot requirements from a disused one, and that affects material choices later in the job.
Chimney rebuilds cannot be done safely from a ladder alone. A chimney stack sits above the ridge, which means working at considerable height with no fixed support. Proper scaffold access is not optional - it is a basic requirement for the job to be done safely and well.
A typical chimney scaffold involves a platform erected around the stack at roof level, often with handrail protection on the perimeter. The scaffold may be freestanding on adjustable base plates bedded on the roof, or tied back to the structure depending on the height and position of the stack. Setting up and striking the scaffold usually adds half a day at each end of the job.
Be wary of anyone who suggests they can do a chimney rebuild from a ladder or with roof ladders alone. The quality of the work suffers when a tradesperson is working from an unstable position, and the safety risk is real.
Once the scaffold platform is in place, the old brickwork is carefully dismantled course by course from the top down to the agreed starting point. On a partial rebuild, this is usually just above the lead flashing. On a more extensive job, it may be back to the roofline or below it.
Bricks are lowered by hand or in a kibble rather than pushed off the scaffold. Broken debris onto a roof or into a garden creates a hazard and risks damaging tiles below. The old lead flashing, flaunching and pot are also removed at this stage and the flue opening is temporarily covered to stop debris entering the flue during the rebuild.
The top of the remaining masonry is then inspected closely. Sometimes a stack that appeared sound at ground level shows additional deterioration once the top is removed - honeycombed mortar joints, cracked bricks, or signs that water has tracked further down the stack than expected. The extent of the rebuild may be adjusted at this point.
The new brickwork is laid course by course, with each course checked for level and plumb as it goes up. The mortar mix used should be appropriate for the bricks being laid - on a traditional older stack, that means a lime-based mortar, not hard cement. Joints are finished to match the profile of the existing brickwork below the new section, whether that is flush, recessed or weathered.
Where the stack serves an active flue, the correct relationship between the pot and the ridge height needs to be maintained. Building regulations and standard practice require the pot to sit at least 1 metre above the roof slope where the stack passes through, to ensure proper draw. This is worth confirming when the pot is being fitted.
The brickwork is built up to full height before the flaunching is applied. New pots are positioned and then bedded into the fresh flaunching, which is formed to slope away from the pot base on all sides so rainwater runs off rather than pooling around the bedding.
New lead flashing is cut and fitted once the stack is at full height. This is one of the most important parts of the entire job. The flashing seals the junction between the stack and the roof slope on all sides, and it is where water most often finds a way into the structure when it fails.
Stepped flashing is cut to follow the rake of the roof slope on either side, with each step tucked into a raked joint in the new brickwork and fixed with lead wedges. The back gutter flashing seals the upslope face. On a tiled roof, soakers sit behind each tile course to make the junction watertight before the cover flashing goes on top.
Code 4 lead is the standard minimum for chimney flashing. The lead is dressed flat against the brickwork face and tiles using a bossing stick or dresser - it should lie in full contact along its length, not just at the edges. The mortar pointing over the top of the tucked edge should be slightly recessed, not overloaded, so it stays in place as the brickwork moves slightly with temperature.
Once the lead is fitted, the mortar joints in the new brickwork are finished - a process called pointing or jointing, depending on whether it is being done as a separate stage. The profile of the joint matters: a slightly weathered profile sheds rain more effectively than a flush finish, which can hold water against the face of the joint.
The new brickwork and mortar should be protected from rain in the first 24 to 48 hours while the mortar begins to cure, particularly if the weather is cold. Hessian or polythene sheeting is used to cover the top of the stack if rain or frost is forecast overnight. This is particularly important with lime mortars, which need longer curing time than cement-based mixes.
Good practice at the end of a chimney rebuild means clearing the scaffold platform of all debris, checking the surrounding roof tiles for any displacement caused by scaffold boards or foot traffic, and inspecting the new flashing from the top and from the eaves to confirm the lead is fully dressed and there are no open gaps.
Any mortar droppings on tiles should be cleaned off before they set hard. Scaffold is then struck and removed, and the surrounding area is cleared of any material that has come down during the job.
Before the scaffolding is removed entirely, it is worth asking the roofer to walk you through the completed work. A few minutes with binoculars from the ground, or a photograph taken from the scaffold platform looking along the new flashing, costs nothing and gives you a record of the finished condition.
If you would like to know what a rebuild would involve on your property specifically, call us to arrange a roof survey and we will talk you through what we find.
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Call any time. Calls are answered day and night and passed straight to our roofers.
