If you are facing a chimney rebuild in Sturmer, knowing exactly what the job involves - start to finish - helps you know what to expect and what questions to ask before work begins.
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A chimney rebuild starts with a proper inspection, and that means getting on the roof - not just looking from the garden or the pavement. A roofer working from ground level cannot assess the condition of the flaunching, check whether the lead flashings are properly dressed into the mortar joints or tell you how many courses of brickwork are affected.
At this point we assess the condition of the brickwork, the mortar, the flaunching, the pot and the lead. We also look at the surrounding roof covering - tiles or slates that are cracked or displaced near the chimney stack should be identified before scaffolding goes up, because it is sensible to deal with them at the same time rather than return to the roof again later.
A chimney rebuild cannot be done safely from a ladder. Scaffolding is not optional - it is a basic requirement for the work to be done to a proper standard. Tower scaffolding or a scaffold lift allows the roofer to work at stack height with both hands free, and to safely lower materials and debris from the stack without dropping anything on the roof surface below.
Scaffolding can be erected quickly on straightforward domestic stacks, but on properties with difficult access - close to boundaries, over a conservatory or garage, or with a long ridge height - it may take longer or require a different approach. The cost of scaffolding is part of the job and should always be included in any quote you receive.
Once scaffolding is in place, the stack is taken down carefully from the top. Bricks are removed course by course to a point below the damage - ideally to sound, stable brickwork. If the whole stack above the roofline is compromised, it comes down to just above the flashing line. In some cases, a stack that appears to be leaning only slightly can be more extensively deteriorated once the first few courses are off, so there is sometimes a degree of variation between the estimated and actual demolition point.
Bricks from the demolished section are lowered to the scaffold platform and cleared from the roof. Old flaunching and any remaining lead are removed, and the remaining brickwork is cleaned back to remove old mortar and debris before rebuilding begins. This preparation stage matters - rebuilding on top of a poorly prepared base is the single biggest reason rebuilt chimney stacks fail early.
The rebuild starts from the cleaned base. New brickwork is laid in the appropriate mortar - on older properties this should be a lime-based mix, not a hard cement mortar which can force stress into softer bricks around it. Each course is checked for level and plumb as the work progresses. A stack that goes up slightly off-plumb will be visibly off-true once the scaffolding comes down, so care at each course is not optional.
New lead step flashings are cut, dressed and set into the mortar joints of the new brickwork as the stack rises. This is a critical detail. Step flashings that are simply stuck to the face of the brickwork with lap sealant will fail within a few years. Properly turned flashings that are mechanically fixed into raked-out mortar joints, then pointed over, will last for decades if the lead is the right code thickness.
At the back of the stack where it sits against the roof slope, a back gutter formed from heavier-gauge lead carries water from behind the stack and out to either side. This is where water most commonly enters when chimney flashings fail - if the back gutter has corroded, been patched or was never properly formed, this is put right as part of the rebuild.
Once the brickwork reaches the correct height, the top of the stack is formed. New flaunching - the sloped mortar bed that holds the pot in position and sheds water - is applied around the pot base. Flaunching should slope firmly away from the pot, be free of cracking and sit neatly against the pot without gaps.
If the existing pot is sound, it can be re-set in the new flaunching. If it is cracked, open at the top or deteriorated, a replacement terracotta pot is fitted at this stage. Where the flue is no longer in use, a capping cowl is fitted to close the flue off against rain and wildlife. For working flues, a rain cowl or anti-downdraught cowl can be fitted if the chimney has a history of downdraught or rain entry through the pot.
Once the chimney work is complete, the surrounding roof area is checked. Any tiles or slates that were dislodged during the build, or that were identified as cracked or slipped during the initial inspection, are replaced. The area is checked for any debris and the lead is pressed firmly into any mortar joints that need attention before the mortar goes off.
This is also the point to check that the new lead flashings are sitting correctly against the tiles or slates below and that there is no gap where water could track under. New pointing mortar on the lead fixings is left to cure; it should not be disturbed or exposed to heavy rain in the first twenty-four to forty-eight hours if possible.
Scaffolding is struck once the mortar and pointing have had adequate time to cure and the roofer is satisfied with the work. Before the scaffolding comes down is the right moment for you to have a look at the finished stack if you want to - ask the roofer to let you know when that window is.
After scaffolding is removed, check the stack from the ground in reasonable light. Look at the plumb of the stack, the evenness of the new brickwork, and whether the pot is sitting centrally and upright. Any concerns are much easier to address before the roofer leaves site than after.
How long the roofing work takes depends on the stack, so it is worth asking for an estimate before work begins. Larger stacks, multi-flue arrangements or stacks requiring extensive lead work will take longer. Ask how long the scaffolding will stay up, including erection, the work period and striking.
The timing can be affected by weather - mortar should not be laid in frost or heavy rain - so some flexibility in the schedule is sensible, particularly in autumn and winter months.
At the end of a chimney rebuild you should have a plumb, sound stack with even coursing, properly embedded lead flashings, firm flaunching around the pot and a pot or cowl that is sitting level. There should be no gaps at the lead to tile junction, no loose mortar debris on the roof and no displaced tiles in the surrounding area.
If any of those conditions are not met when the scaffolding comes down, raise it with the roofer before they leave - do not sign off on work that is not right.
We carry out chimney rebuilds in Sturmer and the wider Haverhill area. If your stack looks like it needs attention, call Haverhill Roofers to arrange a proper roof-level inspection and a clear assessment of what the job involves.
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