Roofing Guide · Bath · March 2026

Chimney Repointing in Bath

Chimney repointing is one of the most frequently requested roofing jobs in Bath, and one of the most frequently done incorrectly. The choice of mortar — lime versus cement — is not a preference issue in Bath: it is a structural and planning compliance issue on the majority of period properties. This guide explains what correct chimney repointing involves and what it costs.

Chimney repointing in Bath costs 250 to 650 pounds for a standard stack. Bath stone and limestone chimneys require NHL lime mortar, while post-war brick uses flexible cement. All four faces of the stack should be inspected, as north-facing sides deteriorate faster than the visible street elevation.

The Mortar Decision — More Important in Bath Than Anywhere

In most UK cities, the choice between lime and cement mortar for chimney repointing is a quality preference. In Bath, it is a structural and legal necessity on a significant proportion of properties. Bath oolite, Doulting stone, and traditional local limestone are all softer than cement mortar. When cement is applied to these materials and thermal cycling opens the joint, the mortar pulls fragments of stone face away with it — spalling damage that cannot be reversed without expensive stone replacement. On listed and conservation area Bath properties, cement repointing of stone chimneys also represents an enforcement risk.

British Standard BS 5390: British Standard BS 5390 for stone masonry sets the joint preparation and mortar specification for repointing — including the rake-out depth needed for a durable repair on Bath's limestone chimney stacks.

How We Assess a Bath Chimney

Every chimney survey covers all four faces of the stack — not just the street-facing elevation. North-facing and rear faces frequently show more advanced mortar failure than the visible front face because they receive less solar drying and more sustained moisture loading. We use a pole camera or access equipment for stacks where ladder inspection does not allow adequate view of all faces.

The survey records: mortar condition as a percentage of failed joints; masonry condition (cracking, spalling, movement); lead flashing condition at base; pot condition and flaunching; and any structural concerns. The written quote covers the full stack condition, not just what was accessible from the visible face.

The Repointing Process

Rake Out

Failed mortar is raked to a minimum 20mm depth using hand tools or a small angle grinder. The depth is important — new mortar packed to less than 15mm has insufficient bond area and will fail prematurely. We do not use large angle grinders on Bath stone or limestone — they overheat the stone and damage adjacent material.

Mortar Application

Lime mortar is applied in layers — a scratch coat to fill the joint body, allowed to firm up, then a finish coat struck to the correct profile. For Bath stone work we prepare a sample panel for the homeowner to approve before committing to the full stack, where the mortar colour matching is critical.

Curing

Lime mortar requires protection from rapid drying for 3 to 5 days after application. In summer weather this means dampening the completed work morning and evening. In temperatures below 5 degrees, lime mortar work is deferred — lime requires warmth to cure correctly and will fail if it freezes within the first 24 hours.

When to Repoint vs Rebuild

Chimney repointing is appropriate when the mortar has failed but the masonry itself is structurally sound — no cracking, no movement, no spalling beyond the surface. When cracking in the masonry courses indicates structural movement, or when more than 40 percent of the courses show open joints, partial or full rebuilding is the correct approach. We identify which is appropriate at the survey stage and explain the reasoning.

For chimney repointing in Bath call 0122 528 7924. Free survey, correct mortar for your property type, written quote.

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Last reviewed: 19 July 2026

Seasonal Timing for Bath Chimney Repointing

Lime mortar chimney repointing in Bath is best carried out between March and October — when temperatures are above 5 degrees consistently and risk of frost within the 24-hour curing window is low. For urgent chimney repointing requirements in winter months, we use an NHL 3.5 mix which has faster initial strength development than NHL 2, and provide temporary waterproofing of the worst-affected joints using compatible lead tape while conditions improve.

The pre-autumn window — August to September — is ideal for planned chimney repointing on Bath properties. Work completed in this window has a full curing season before the first frost, giving the lime mortar time to develop full strength before the most demanding weather of the year. We typically have good availability for chimney surveys in August with work completable before October.

Chimney Repointing Costs Across Bath

Chimney repointing costs across Bath and surrounding areas: standard single-flue stack to approximately 3 metres above roof level, lime mortar, scaffold from existing roof access — £350 to £550. Taller Georgian or Victorian stacks requiring a mobile elevated work platform or additional scaffold — £500 to £800. Full stack rebuild in lime mortar and matching stone — £800 to £2,500 depending on stack size. Lead saddle and step flashing replacement at the same time as repointing — add £300 to £700 depending on the flashing extent. All work is quoted in writing before starting. Call 0122 528 7924 to arrange a free chimney assessment.

Step-by-Step: What Chimney Repointing Involves

A chimney repointing job on a Bath period property follows a consistent process. Survey: we inspect all four faces of the stack from the closest accessible point — street elevation, rear, and both sides where visible. We note the mortar condition, the masonry type, any lead flashing condition, and any structural concerns such as cracked courses or movement at the stack base. Written quote: the quote specifies the extent of repointing, the mortar specification, any lead or flaunching work included, access equipment, and the total cost.

Raking out: old mortar is raked to a minimum 20mm depth using hand tools or a narrow disc cutter for hard cement joints. The face of the brick or stone is cleaned of dust and loose material. For Bath stone and limestone, raking is always done by hand — power tools cause irreversible surface damage on soft oolite. New mortar: NHL lime mortar is mixed on site to the correct ratio, colour-matched using iron oxide pigments where needed, and applied in one or two passes to fill the joint to slightly below face level. The struck profile is matched to the original — flat bed joints on Georgian stack, slightly recessed on Victorian brick.

Curing: lime mortar must be protected from rapid drying for 3 to 5 days in dry weather. We use damp hessian or polythene cover over the work area where needed. In cold weather below 5 degrees, lime mortar work is deferred — frost damage to uncured lime mortar is irreversible. Final inspection: the completed work is inspected from scaffold before dismantling. Photographs are taken for the written record. For listed properties, the mortar specification and photographs are provided for the conservation file.

How Long Should Chimney Repointing Last in Bath?

NHL lime mortar repointing on a Bath stone or limestone chimney, correctly mixed and cured, should last 40 to 80 years — comparable to or exceeding the original lime mortar it replaces. Flexible cement repointing on Victorian brick in sheltered positions should last 20 to 30 years. Rigid cement repointing on Bath stone typically fails within 10 to 20 years through differential movement and causes stone damage in the process. The 20-year cost of three cement repointing jobs plus the stone remediation cost is almost always higher than the cost of one correct lime mortar job. Call 0122 528 7924 for a free chimney assessment.

Free Chimney Repointing Survey in Bath — How to Book

We cover Bath and all surrounding areas for chimney repointing survey work across the full BA1, BA2, BA3, BS31, BA11, BA14, BA15, SN12, SN13 and SN14 postcode areas. Free assessments within 2 to 5 working days. Emergency attendance within 60 to 90 minutes for Bath city addresses. All work quoted in writing before starting. 10-year workmanship guarantee. No call-out fee on any visit.

Chimney repointing surveys include inspection of all four faces, a written mortar specification, and a fixed-price quote before any work starts. Emergency chimney repair attended same day for active water ingress.

Call 0122 528 7924 to arrange a free assessment. Our team will confirm availability immediately and give you an honest assessment of what is needed — no upselling, no pressure, no obligation to proceed. If repair is the right answer we will say so. If replacement is the right answer we will explain why.

FAQ

Frequently Asked Questions

Chimney repointing on a standard single stack costs £250 to £650 depending on stack height and the extent of mortar failure. Taller stacks requiring mobile access or scaffold cost more. Free quotes for all chimney work.

NHL 2 lime mortar for Bath oolite and Doulting stone properties. NHL 3.5 for harder limestone and traditional brick. Flexible cement for post-war dense brick. Never cement mortar on any period masonry.

Correctly applied lime mortar repointing lasts 40 to 80 years. Flexible cement on post-war brick lasts 20 to 30 years. Cement mortar on traditional masonry fails within 10 to 20 years and causes stone damage in the process.

For stacks taller than a single storey, scaffold or a mobile elevated work platform is required for safe access. Single-storey stacks can often be accessed from a ladder. We confirm access requirements at the survey stage.

On lime mortar chimneys, selective repointing of failed joints is generally appropriate. On cement-pointed chimneys being converted to lime, the existing cement should be removed in full before lime is applied — lime over cement does not bond correctly.

We assess and include flaunching repair as part of every chimney repointing visit where it requires attention. Failed flaunching is quoted separately but is inspected as standard.

No. All assessments are free with no call-out fee.