If you have a chimney stack in Fulbourn that needs rebuilding, here is exactly what that job involves, from the initial survey through to the point we take the scaffold down and leave the site clear.
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No chimney rebuild should be priced from ground level alone. A proper survey means getting eyes on the stack itself - which requires either scaffold, a tall ladder secured at the top, or in some cases a drone survey where the stack is not immediately accessible. We assess the brickwork condition course by course, check the flaunching, inspect the pots, look at the condition and fit of the lead flashing, and check whether the top of the chimney breast inside the roof space shows signs of water tracking down internally.
The survey establishes two things: how far down the stack needs to come, and what the cause of the problem is. These are not the same question. A stack can look visually deteriorated from below but be sound from a certain course down. Conversely, a stack that looks acceptable can have badly eroded internal joints that only show when you are standing next to it. The extent of the rebuild - and therefore the cost - depends on what the survey finds, not on what the problem looks like from the garden.
We cover Fulbourn, Haverhill and the surrounding area. The survey tells us what work is actually needed before we commit to a scope or a price.
A chimney rebuild above the roofline cannot be done safely from a ladder. Scaffold is erected around the stack, typically a small chimney lift or independent scaffold that allows the roofer to stand safely adjacent to the stack and work both hands free. On a two-storey house this usually means the scaffold stands on the main roof slope, tied to the chimney stack itself before work begins.
The scaffold is erected before any other work starts. It stays in place until everything - brickwork, flaunching, pots and lead - is finished and inspected. Rushing the scaffold down to save a day is a false economy. On a terrace or semi-detached property, the scaffold position needs to account for neighbour access and any protected plants or structures below.
Scaffold costs are part of the job, not an optional extra. Any quote that does not include access equipment should be questioned.
The pots come off first, set aside if they are to be reused or removed if they are cracked or the wrong type for the job going forward. The flaunching is broken off - it is almost never salvageable and is always replaced. Then the brickwork is taken down course by course to the point agreed at survey stage.
This is not a case of knocking the stack over. Each course is carefully removed, brick by brick, lowering materials by hand or in a bucket and rope rather than dropping them. Material dropped from chimney height onto a tiled roof causes more damage than the repair is worth. A good roofer removes mortar from each brick face as it comes down, working methodically rather than quickly.
The rubble and old mortar are cleared from the scaffold platforms at regular intervals throughout the day to prevent build-up and keep the working area safe.
Once the stack is down to the agreed course, we look again at the brickwork beneath. Occasionally the survey will have predicted the stopping point correctly and work starts straight away. Sometimes the brickwork one or two courses below the original target is softer or more water-damaged than expected, and the decision needs to be made on-site to take it down a little further.
This is not unusual and not a sign of a job going wrong - it is the nature of chimney work on older property. The customer should be informed immediately if the scope changes, with a clear explanation of why and what the additional cost is. Carrying on silently and adjusting the invoice later is not acceptable practice.
The exposed top of the remaining stack is checked for soundness. Any loose or soft mortar in the remaining joints is raked out ready for repointing as part of the rebuild process.
New brickwork goes up course by course, with each course checked for level and plumb. The mortar mix is prepared to the right consistency - not too wet, not too stiff - and applied to bed and perpend joints. Joints are struck off flush or slightly recessed as agreed; a heavily raked or beaded joint profile on a chimney stack, while it can look smart, creates ledges where water sits.
Corners are properly bonded, not just butted. The stack is built plumb throughout - a leaning rebuild is a wasted job. On a shared or party stack, the dividing course between flues must be correctly maintained to prevent cross-flue issues.
Where the original stack had any through-the-wall ties or restraints to the main roof structure, these are reinstated. A tall or slender stack without adequate restraint is at greater risk of future movement.
The lead flashing is the joint between the stack and the roof slope, and it is typically fitted once the brickwork has had at least a day to begin setting, so the mortar joints are stable enough to accept the lead without disturbing them.
The stepped side flashings are cut and dressed in sections, each piece stepped up or down to follow the course of the tiles. They are turned into raked joints in the brickwork - the joint is raked out 25mm minimum before the lead is folded in - then pointed over with a flexible mortar or appropriate sealant. The front apron covers the lowest few courses at the front of the stack and is tucked under the first course of tiles above it. The back gutter sits behind the stack, collecting water that runs down the roof slope behind it and directing it to the sides.
Code 4 lead is the standard for residential chimney work. Where the flashing width or exposure warrants it, code 5 is used. Proprietary self-adhesive products are not a like-for-like substitute for dressed lead and should not be presented as one on a rebuild job.
Flaunching is mixed and applied once the lead work is complete. It is built up around the base of each pot, sloping outward from the pot to the edge of the stack so that rainwater sheds away from the pot base rather than pooling. Each pot is bedded into the wet flaunching and checked for vertical - a pot that leans slightly sits unevenly on the stack and can admit water at the base.
The flaunching is finished to a smooth, even slope with no lips or dips where water can collect. It is left to cure without being disturbed. In cold or wet weather, curing flaunching should be covered and protected from frost - a frost-damaged flaunch will crack within months of being laid.
If cowls or caps are being fitted in place of open pots, they are secured at this stage. A capping cowl on a redundant flue must seal properly at the base - a cowl simply dropped onto a pot with no fixing or bedding is a temporary measure at best.
Before the scaffold comes down, the finished stack is inspected. Every joint is checked for soundness, the flaunching is checked for adhesion and slope, the lead is checked for gaps at the top edges and for any lifted sections, and the pots or cowls are checked for seating and vertical. If anything is not right, it is corrected on the scaffold before access is removed.
The scaffold is then struck, the roof slope beneath it is checked for any tile damage caused during erection or use, and all materials are removed from site. The chimney breast inside the property should be checked a few weeks after the job in wet weather - if there is any residual damp from pre-existing saturation in the walls, it will dry out over weeks; new water ingress after a correctly executed rebuild should not occur.
How long a chimney rebuild takes depends mainly on the size and complexity of the stack. Larger stacks, shared stacks or those with complex lead work take longer. Scaffold erection and striking add time at either end of the job.
We carry out chimney rebuilds in Fulbourn, Haverhill, Cambridge and the villages between. If your stack needs attention, call us to arrange a proper survey and we will give you a clear scope and price before any work starts.
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Call any time. Calls are answered day and night and passed straight to our roofers.
