Chimney repointing
In short
A stack takes weather from four sides with nothing above it, so its mortar erodes long before the rest of the house. Repointing means raking out to a proper depth and refilling with a mortar matched to the brick — not smearing a hard cement over the top of what is there.
Also called: Repoint chimney · Chimney mortar · Chimney brickwork repair · Pointing chimney stack
Signs you need this
- Mortar joints visibly recessed, crumbling or missing
- Sand or mortar debris in the gutters below the stack
- Damp staining on the chimney breast inside
- Brick faces spalling — flaking off in layers
- Vegetation or moss growing out of the joints
- Previous pointing that is cracked or falling away in strips
Pointing is the sacrificial part of masonry. It is meant to erode slowly and be renewed, protecting the brick or stone either side of it — and on a chimney, which stands clear of the building and gets the full weather from every direction, it erodes several times faster than the walls below.
Once the joints have gone back far enough, the brickwork starts taking up water directly, and a saturated stack is both a source of internal damp on the chimney breast and a candidate for frost damage. That is the point at which repointing stops being maintenance and becomes a repair.
The job itself is straightforward and frequently done badly. The old mortar has to be raked out to a depth of at least twice the joint width, cleanly, back to sound material — not scratched at the surface. The joints are wetted, and the new mortar is worked in properly in layers on a deep joint, then finished to a profile that sheds water. Skim-pointing over eroded joints, which is the commonest bodge, holds for a couple of winters and then falls out in sheets, taking the surface of the brick with it.
Mortar mix matters more than almost anything else here, and getting it wrong causes real damage. Old soft brick and stone need a mortar softer than they are — traditionally lime-based — so that the mortar erodes rather than the masonry, and so that moisture can escape through the joint. A hard modern cement mortar on soft Victorian brick traps water in the brick, which then spalls its face off in the first hard frost. There is a great deal of that in this town, and a great deal of it was done with the best intentions.
Frost is the reason the mix matters more up the hill. Air frost increases sharply with altitude — the Met Office records around 20 frost days a year on the North West coast against over 75 in the higher Pennines, and roughly half a degree of cooling per hundred metres — so a stack in Rainow or Kerridge gets many more freeze-thaw cycles a year than one in the town centre. Wrong mortar plus more frost is how a stack goes from tired to rebuilt.
One practical point on a terrace. A stack sitting on the party wall is normally a party structure, so significant work to it falls under the Party Wall etc. Act 1996 and the neighbour needs written notice — two months for work to a party structure. Repointing your own face of a shared stack is usually uncontroversial; anything more, and it is much easier to do the paperwork at the start.
What the job covers
- Joints raked out to proper depth, back to sound material
- Mortar mix matched to the brick or stone — softer than the masonry
- Joints finished to a weather-shedding profile
- Spalled or badly damaged bricks cut out and replaced
- Flaunching and flashing checked at the same time
- Party Wall position flagged where the stack is shared
What it costs
We don't publish a price for this yet, because a number pulled out of the air is worse than no number at all — your roofer has to honour it. On roofing it would also be close to meaningless: access is often the biggest single factor, and it varies enormously house to house. You'll get a firm price for your actual job when they ring you back, before any work starts. The quote itself is free and there's no obligation either way.
Common questions
Can you just point over the top of the old mortar?
No — and it is the commonest bad repair on a chimney. Skim-pointing over eroded joints gives no depth to bond to, so it falls out within a couple of winters, and it often takes the arris off the brick with it. The old mortar has to come out to at least twice the joint width first.
Does the mortar mix really matter?
A great deal, and getting it wrong causes damage that pointing was supposed to prevent. Old soft brick needs a mortar softer than itself, traditionally lime-based, so the joint erodes instead of the brick and moisture can escape. Hard cement mortar on soft Victorian brick traps water and spalls the brick faces off in frost.
How often does a chimney need repointing?
There is no schedule — it depends on exposure, the original mortar and the aspect. A sheltered stack in the town might go fifty years or more; an exposed one on the high ground with a hard cement mortar can need attention in twenty. The honest measure is the depth of the joints, not the age of the last job.
Do I need a scaffold to repoint a chimney?
Almost always, yes. A stack is at the highest point of the building, the work takes time, and it involves both hands. That is not a ladder job under the Work at Height Regulations, and on a terrace fronting the pavement the scaffold may need a highway licence from Cheshire East — which is why it belongs in the quote.
Need this doing in Macclesfield?
Tell us the job and it goes straight to our local roofer — one call back, usually the same day. Free quote, no obligation.