Newmarket Roofers carries out chimney rebuilds in Girton, working through a clear process from the first inspection to final scaffold removal and clean-up.
Homeowners often ask what a chimney rebuild actually involves and how long the whole thing takes. The process has a clear sequence, and understanding each stage helps you know what to expect, what questions to ask, and how to judge whether the work has been done properly. This page walks through the job from start to finish.
A proper chimney inspection cannot be done from the ground. Binoculars will reveal obvious problems - a visible lean, large open joints, a pot that is clearly out of position - but the true condition of the pointing, the flaunching, the lead flashing, and the individual bricks can only be assessed at close quarters. We erect scaffold before making any definitive assessment of what work is required.
During the inspection, we check every course of brickwork from the roof line to the top of the pot. We look at the condition of the mortar joints, test bricks for soundness by probing and tapping, assess the flaunching around the pot, and inspect the lead flashing at the base of the stack where it meets the roof. We also check whether the stack is plumb - a lean of even a few degrees indicates that courses have moved and the structure is compromised.
Only after that inspection can we give you an accurate scope of work. A quote produced before scaffold goes up and the stack is inspected at close range is, at best, an estimate based on guesswork.
All our chimney work is carried out from purpose-built scaffold. The scaffold is designed to give safe, stable working access to every face of the stack. For most domestic chimneys, this means a lift of boards at ridge or just above it, tied to the structure and with guard rails on all open sides. The scaffold goes up before any work begins and comes down only after everything is complete and checked.
Scaffold is not optional and is not a sign of an over-cautious contractor. A chimney stack is typically 5 to 8 metres above the gutter line by the time you account for the roof pitch. Attempting to relay brickwork, dress lead, or bed a pot from a ladder at that height is not just dangerous - the quality of the work cannot be controlled without a stable platform to work from.
Once on scaffold, we remove the courses of brickwork that are beyond repoint or repair. The number of courses taken down depends on the condition of the stack. Sometimes only the top four or five courses above the haunching are affected. On a stack that has been neglected for a long time, or where mortar mismatch has accelerated decay, more courses may need to come down to reach sound, stable brickwork to build from.
Bricks are assessed as they come down. Sound bricks are retained if they match and are structurally intact. Spalled, cracked, or hollow-sounding bricks are discarded. Any debris is cleared carefully - loose bricks and mortar at height are a safety hazard and must be controlled, not simply knocked off the edge.
Where the lead flashing is disturbed or found to be failed during this stage, it is dressed out and set aside. New lead will be formed and fitted as part of the rebuild.
New courses are laid from the highest sound course upward, using a mortar mix appropriate for the age and type of the existing brickwork. For older properties, that typically means a lime-based or lime-rich mix rather than a strong sand-cement mortar. Using a mortar stronger than the brick causes stress to transfer into the brick face - a common cause of new spalling appearing within a few years of a repair.
Each course is laid level and plumb, with consistent joint widths. Mortar is pressed firmly into the joints and finished flush or with a slightly recessed profile to shed water effectively. Bed joints (horizontal) and perpend joints (vertical) are both filled - a chimney with gaps in the perpends is still an open stack, even if the beds look sound.
Where replacement bricks are needed, we try to source material that matches the original in colour, texture, and density. A visible colour difference between old and new brickwork is normal initially and generally weathers down over time, but a density mismatch will cause problems under frost regardless of how it looks.
The chimney pot is set in position on the top course and secured with fresh flaunching - a sloped mortar collar that supports the pot, seals the top of the stack, and sheds water away from the brickwork below. Old flaunching is broken out completely before new material is applied; patching over existing failed flaunching is not a sound repair and will not hold.
The flaunching is applied in a smooth, even slope from the base of the pot down to the top edge of the uppermost brick course. It should be approximately 45 degrees in profile so water runs clear rather than pooling. A pot that is set at the correct height for the flue opening, bedded level, and surrounded by properly sloped flaunching will resist water entry effectively and remain stable.
If the pot itself is cracked or damaged, it is replaced. A new terracotta pot matched to the flue opening size is the standard replacement. The pot is checked for plumb before the flaunching is finished.
Lead flashing at the base of the stack is the seal between the chimney and the roof. It is made up of several components - the back gutter behind the stack, the side step flashings that follow the roof slope, and the front apron below the stack. Each section is formed from lead sheet and dressed into the mortar joints of the brickwork, then pointed in to hold it secure.
Where existing lead is in good condition it can be redressed and repointed. Where it is cracked, lifting, or has been patched with sealant over the years, new lead is cut and fitted to the correct code (typically code 4 for domestic work). Lead sealant alone is not a long-term repair for a failed flashing - it degrades and allows water back in.
Once the brickwork, flaunching, and flashing are complete, all tools and materials are removed from the scaffold. Any mortar droppings on the roof tiles below are cleared. The scaffold is then struck and removed, and the area around the property is left clean. Before the scaffold comes down, the completed stack is inspected again from the working platform to confirm every joint is filled, the flaunching is smooth and fully adhered, and the lead is correctly dressed on all sides.
We carry out chimney rebuilds in Girton and across the surrounding area. If you have a chimney stack that needs attention, call us to arrange a proper inspection from scaffold so we can give you an accurate account of what is needed.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
