From the first proper inspection to clearing the last brick dust from your roof tiles, a chimney rebuild follows a clear sequence of work - North Walsham Roofers carries out chimney rebuilds for homeowners in Sheringham and nearby.
Most homeowners have never watched a chimney rebuild from start to finish, which makes it hard to know what to expect, how long it takes, or whether the work is being done properly. This page walks through the process in the order it actually happens, so you know what each stage involves and what to look for at each point.
Any chimney assessment worth acting on is done from close range. A view from the ground or from a bedroom window gives a general impression, but it cannot tell you whether individual bricks are soft, whether the mortar joints are failing at depth, or whether the flashing is still holding at the raglet. An inspection from scaffold level - or at minimum from a properly secured roof ladder on a low pitch - is the only way to make a reliable judgement about what needs doing.
At this stage, a roofer should be checking the condition of every face of the stack, the state of the mortar joints throughout, the flaunching (the mortar cap around the chimney pot base), the pot itself, and the full run of the lead flashing at the roof junction. If the chimney serves a working fireplace, the flue opening should be checked for signs of liner damage. The findings should be explained to you clearly before any work is priced or agreed.
A chimney rebuild cannot be carried out safely or properly from a ladder. A scaffold platform that gives safe, stable access to all four faces of the stack is a basic requirement for the job. On a typical two-storey house, this means a scaffold tower or a bridging scaffold arrangement that brings the working platform to just below chimney height.
The scaffold needs to be properly footed and tied. A poorly erected scaffold is a risk to the workers on it and to anyone below. If a roofer quotes for chimney work without mentioning scaffold, ask directly how they intend to access the stack - and be cautious if the answer involves only a ladder.
For most residential chimney rebuilds, the scaffold is in place for the duration of the work and is then struck and removed as a separate operation, usually on the same day as the final inspection.
Once the scaffold is up and the roofer is at working height, the failed section of the stack is carefully taken down course by course. The aim is to remove every brick and every bit of old mortar back to the point where the remaining brickwork is genuinely sound - not just to where it looks acceptable from arm's length.
Bricks are lowered or passed down rather than thrown - dropping debris onto a roof slope or into a garden is poor practice and can cause damage. Good site discipline at this stage protects your roof tiles, your guttering and your garden.
The top of the remaining section is cleaned back to a flat, level bed. Any loose or soft bricks in the courses just below the cut line are replaced at this point rather than built over. Building new work on top of a suspect course is one of the most common shortcuts in chimney repairs, and it shortens the life of everything above it.
If the flashing is being replaced as part of the rebuild - which it should be in most cases where the stack is coming down to roof level - the existing lead is removed at this stage. The raglets (the grooves cut into the mortar joints to hold the flashing) are cleaned out ready for the new lead to be fitted.
If the flashing is in good condition and the rebuild is only from mid-stack upward, the flashing is carefully protected during the demolition and rebuild phases. Mortar droppings on lead flashing are not just messy - mortar is alkaline and can attack the surface of the lead over time if left in contact with it.
New brickwork goes up course by course, with each bed of mortar given time to set before the next course is laid. Rushing this - laying too many courses in one session on fresh mortar - allows the weight of the new brickwork to squeeze the joints before the mortar has begun to stiffen, producing uneven joint widths and a stack that is not truly plumb.
Each course should be checked for level and for plumb (vertical alignment). A chimney stack that leans is not just unsightly - it puts uneven loading on the courses below and increases the risk of failure in wind. The bricks should be laid with the correct mortar for the type of brick being used (lime mortar for older soft bricks, sand-and-cement for modern ones) and the joints struck or pointed to match the surrounding work.
Where the rebuild is a partial one - starting from mid-stack - the first new course is bonded into the existing brickwork in the same way brickwork is always bonded: staggered joints, with each new brick crossing the joint below. A straight vertical joint between old and new work is a weakness and should not be accepted.
Once the new brickwork has been laid to the correct height, the lead flashing is fitted at the roof junction. Step flashing is worked up the slope of the roof beside the stack, with each piece overlapping the one below and tucked under the tile course above. The counter flashing (sometimes called cover flashing) is dressed over the top of the step flashing and is tucked into the raglets cut into the new mortar joints.
The raglets are then pointed with mortar or a suitable flexible sealant to hold the flashing securely. Lead wedges are driven in before pointing to prevent the flashing pulling out as the lead expands and contracts. This detail is easy to skip and easy to miss from the ground, but it is the difference between a flashing that stays put for many years and one that starts lifting within a couple of seasons.
The chimney pot is bedded in mortar at the top of the rebuilt stack. The mortar is haunched - built up and sloped away from the pot on all sides - so that water runs off rather than pooling at the base. The haunch should be smooth and slightly proud of the surrounding brickwork, not flat or recessed.
If the chimney is redundant, a ventilating cap is fitted in place of an open pot. If a new pot is being fitted, the type and height should match the draught requirements of the fireplace or stove it serves.
Before the scaffold comes down, the finished stack should be checked from all angles. The brickwork should be plumb, the joints should be consistent, the pot should be solidly bedded, and the flashing should be tight along its full length with no gaps or lifted sections. Any mortar splashes on surrounding tiles or on the flashing itself should be cleaned off while they are still workable - dried mortar is much harder to remove and can chip tile glazing.
Once the scaffold is struck, the work area should be cleared of all debris. Old bricks and mortar rubble should be removed, not left in the garden or on the roof slope. A clean finish to the job is a reasonable expectation, not an extra.
We carry out chimney rebuilds in Sheringham and across the surrounding area. If you want to talk through what a chimney rebuild would involve for your specific property - the access arrangements, the likely scope of work or anything else - call North Walsham Roofers for a straightforward conversation before any work is agreed.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
