Chimney repair in Lewisham

A chimney is the hardest-working and least-inspected part of most South East London roofs. By the time a problem shows up indoors, it has usually been developing outside for several winters.

We repair chimneys across the London Borough of Lewisham — Catford, Brockley, Hither Green, Forest Hill, Sydenham, Deptford, Blackheath and the surrounding SE postcodes. Most of what we do is on period stacks: soft London stock brick, lime mortar, tall and exposed, and often carrying flues that have not been used in fifty years.

What "chimney repair" actually covers

It is worth being precise, because the phrase covers several genuinely different jobs at very different costs. A chimney is an assembly of parts, and repair means fixing whichever part has failed:

The pots and the flaunching

Clay pots crack, and the mortar cap they are bedded into — the flaunching — is the single most common failure on any chimney. It is thin, fully exposed, and once it cracks, water runs straight down inside the stack rather than off it. Because the two are physically bound together they are effectively one job. See chimney flaunching and pot repair for what that involves.

The brickwork and joints

Open, hollow or missing mortar joints let water into the body of the stack. Left long enough, saturated brick faces blow off in frost — that is spalling, and it is not reversible. Once you have lost the outer face of the bricks, pointing no longer solves it. See chimney repointing.

The flashing

The weatherproof junction between the stack and the roof covering. Failed lead, or the cement fillets that were often used instead of lead, are a very common source of leaks that get blamed on the chimney itself. See chimney flashing repair.

The structure

Where a stack has moved, is leaning, or has deteriorated beyond the point that pointing will help, the work becomes structural — a partial or full rebuild. See chimney stack repair and rebuild.

The faults we are called out to most

• Damp on the chimney breast in a bedroom or top-floor room, worse after driving rain
• Cracked or eroded flaunching visible as a broken mortar cap around the pots
• Open mortar joints — you can see daylight through them, or rake them out by hand
• Spalled brick faces where the outer skin has flaked away, often on the weather side
• Debris in the gutter — sand, mortar crumbs or brick fragments after wind
• Failed or lifted lead, or cement fillets that have cracked away from the brickwork
• A stack out of vertical, or one that has visibly moved relative to the roofline
• Vegetation growing out of the stack — always a sign that joints have opened up

What you can see, and what it usually means

Chimney problems present as a handful of recognisable symptoms, and each points at a fairly specific cause. Find yours below — each row links to the page that explains that problem properly.

Repair or rebuild? How the decision is actually made

This is the question that determines the cost, so it deserves a straight answer rather than a sales pitch.

Repair is usually appropriate when the brickwork itself is sound and the failure is in the mortar, the flaunching, the pots or the flashing. The bricks are the expensive, irreplaceable part; if they are in good condition, everything around them can be renewed.

Rebuilding becomes the sensible option when the brick faces have spalled through, when joints have eroded so deeply that there is nothing left to point into, when the stack has moved, or when previous hard-cement repairs have trapped moisture and damaged the brick behind. At that point repointing is spending money on a stack that will need doing again.

Very often the answer is partial: the top three or four courses — the most exposed part — are rebuilt, and the sound brickwork below is repointed. That is a common and cost-effective outcome on Lewisham terraces, and it is usually only clear once someone has looked at the stack properly rather than from the pavement.

How we assess a chimney

An honest assessment looks at more than the thing you have noticed:

• The stack from roof level where access allows — brick condition, joint depth, whether mortar is sound or sandy
• The flaunching and pots, including hairline cracking that is invisible from the ground
• The flashing and the chase it is dressed into
• The roof covering immediately around the base, which is where a lot of "chimney" leaks actually originate
• Inside, where relevant — the pattern and position of staining on the breast tells you a lot about where water is entering
• Whether the stack is shared with a neighbouring property, which affects both the work and who is responsible for it

Access and scaffolding

Most work on a stack above the roofline needs a proper working platform. That means scaffolding, and it is a real part of the cost — frequently a significant proportion of a smaller job, which is why it rarely makes sense to do flaunching now and pointing next year. If a stack needs several things doing, doing them under one scaffold is almost always cheaper than doing them one at a time.

Where a stack is on a shared party wall, or where access runs over a neighbour's property, that needs arranging in advance. We will flag it when we quote rather than on the morning of the work.

What it costs

Chimney work spans a very wide range — from recasting flaunching through to a full rebuild with scaffolding. We have set out what drives the price, and the realistic bands, on the chimney repair cost page. We do not quote firm prices without seeing the stack, because the difference between "point it" and "rebuild it" is not visible from the street.

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Chimney repair questions