Brandon Roofers rebuilds chimney stacks for homeowners in Soham, and once the work is done we want it to last - so this page covers not just what a rebuild involves, but what you can do to keep your chimney in good condition for years afterwards.
A chimney rebuild starts by taking the stack down to the lowest course of sound brickwork. From there, the stack is rebuilt upward with bricks matched as closely as possible to the existing ones, bedded in the correct mortar mix for the age and type of the property. The top is finished with new flaunching - the sloped mortar collar that seats the pots and drains water away from the stack. Where the stack meets the roof, the lead flashing is inspected and replaced where necessary using properly stepped and soaked lead rather than a mortar fillet or mastic.
The work requires scaffold or a proper working platform, not a ladder. It takes at least most of a day on a standard stack. The bricks used should be selected to match the colour, texture and size of the existing chimney - a stack rebuilt in obviously mismatched bricks is a sign that this step was skipped.
Chimney stacks are the most exposed part of a house. They sit above the roof line where they catch wind and rain from every angle, and they cycle between extremes of temperature as the flue heats up with use and cools again. Frost is a particular problem: water in mortar joints or brick faces freezes, expands slightly, and over many winters gradually breaks the material apart. Mortar joints typically deteriorate before the bricks do, and if they are not caught early the bricks start to displace and the stack loses its structural integrity.
Sulphate attack from flue gases gradually degrades certain mortar types from the inside, and is a common cause of mortar failure in chimneys on properties that have used solid fuel. A stack can look sound from the ground but have significant internal breakdown in the mortar.
Flashing is the lead detail that seals the joint between the chimney stack and the roof covering. It fails when lead is fixed too rigidly and thermal movement causes it to crack or pull away from the brick, when the mortar pointing in the step chase (the groove where the flashing edge is tucked into the brick) shrinks and releases the lead, or when original flashing was mortared rather than properly chased and soaked. Once flashing is open, rainwater tracks down behind it into the wall or ceiling below - which is why a damp patch on a chimney breast wall inside the house is often a flashing problem rather than a roof tile problem.
A properly rebuilt chimney, with the right mortar and well-fitted flashing, should give you many years of trouble-free service. But there are practical things you can do to extend that and catch problems early, before they become expensive again.
The flaunching at the top of the stack is the most vulnerable point. Look at it from the ground with binoculars if you can. You are looking for visible cracks, sections that appear to have dropped or separated, or pots that seem to have shifted position. Hairline surface cracks in new flaunching in the first winter are not unusual - wider cracks that go through the depth of the flaunching, or sections that have lifted away, need attention before the next frost season.
After a period of heavy rain, check inside the house at the chimney breast on each floor. A damp patch, staining or fresh efflorescence on the plaster near the chimney breast is a sign that water is getting in somewhere. Flashing problems are easier and cheaper to fix when caught early rather than after water has been tracking behind the lead for a full winter.
A chimney sweep is not just about removing soot. A sweep will also check the condition of the flue liner, the pot and the stack from the outside, and is often the first person to notice a mortar joint opening up or a displaced brick that is not obvious from the ground. Annual sweeping for a regularly used wood burner or open fire is standard practice and keeps the flue safe. A sweep is not the same as a structural roofer, but the two trades often refer work to each other.
If you cap or seal a chimney that is no longer in use, ventilation is still needed to prevent condensation forming inside the flue. A capping cowl with ventilation holes rather than a solid cap is the right solution. A sealed flue with no airflow will attract moisture, which then saturates the brickwork and mortar from the inside - sometimes causing more damage than leaving the pot open would have done.
For a chimney that is genuinely never going to be used again, a vented cap fitted into the pot is the lowest-maintenance solution. It keeps rain, birds and debris out while allowing the flue to breathe. Fitting a cowl properly means seating it into good flaunching - if the flaunching is cracked, sort that first.
Yes. Older and listed properties require lime mortar rather than cement, and matching reclaimed or handmade bricks where the original type is no longer in standard production. If the property is listed, it is worth confirming with your local planning authority whether the planned work requires consent before it begins - changing the character of a chimney on a listed building can fall within the scope of listed building controls.
We assess the stack from the ground using binoculars first, then get to close range on scaffold or a tower to inspect the individual bricks, mortar joints, flaunching, pots and flashing in detail. We tap bricks and check for the hollow sound that indicates mortar breakdown behind the face, check whether the stack is plumb, and look at how the flashing is seated at roof level. The inspection gives us the information we need to tell you what needs doing and why.
A typical full chimney rebuild on a standard two-pot stack runs from around £1,500 to £3,000 in the UK, depending on the number of courses to be rebuilt, the complexity of brick-matching required and whether new flashing is needed. Scaffold is included in a properly priced job. Larger stacks or those needing reclaimed bricks will cost more. Repairs such as repointing or flaunching replacement are considerably less.
No. A chimney sweep deals with the inside of the flue - clearing soot, checking the liner and ensuring the flue is safe to use. A roofer deals with the structural and weatherproofing elements: the stack brickwork, flaunching, flashing and the roof covering around the chimney base. Both trades have a role in maintaining a chimney, but they are different jobs requiring different skills and equipment.
If your chimney stack has been rebuilt or repaired and you want to make sure it stays in good shape, or if you think something is starting to go wrong and want it assessed before it gets worse, call Brandon Roofers. We cover Soham and the surrounding area from our base in Brandon, and we will give you a straight assessment of what the chimney needs.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
