Chimney repointing

Chimney repointing deals with the part of the house that takes the most punishment: a chimney stack stands exposed above the roofline on every side, taking more direct weather than any other brickwork on the house, and the mortar joints between the bricks erode faster there than almost anywhere else on the property. Once water gets into cracked joints it works into the brick itself and, eventually, down into the roof structure and the room below.

Why mortar joints fail first

Mortar is more porous and less durable than the brick it holds together, by design, since it is meant to be the sacrificial element that gets replaced periodically rather than let the bricks themselves erode. On an exposed chimney stack, decades of frost, rain and wind erode the joints, and once cracks appear, freeze-thaw cycles in winter widen them quickly.

What repointing involves

• Raking out the old, failed mortar to a consistent depth
• Cleaning the joint of loose material and dust before repointing
• Repointing with a mortar mix matched to the age and type of the original brickwork, since a modern hard cement mix on an older, softer brick can trap moisture and cause the brick face to spall
• Finishing the joint profile to match the existing pointing style

Getting the mortar mix right matters more than people expect. On period properties common across the Fens, a lime-based mortar is usually correct, allowing the brick to breathe, while a hard modern mix can do more harm than good over time.

The finished joint profile matters too, whether it is struck flush, weathered or bucket handle, matching the original finish keeps the repointing looking consistent with the rest of the stack rather than an obvious patch job visible from the ground.

Signs a chimney needs repointing

• Visible gaps or crumbling mortar between the bricks
• Mortar debris found in the guttering below the chimney
• Damp patches appearing on a chimney breast inside the house
• A stack that looks visibly weathered or eroded compared to the rest of the roof

What is often checked at the same time

While scaffolding is up for repointing, we check the flaunching and lead flashing at the base of the stack too, since these commonly need attention around the same time. See our lead flashing and valleys page and our wider chimney repairs and leadwork page.

What you get

Repointing carries our 10 year written workmanship guarantee. See our chimney repair cost guide for typical pricing.

A newly repointed stack should look consistent with the rest of the chimney once the mortar has cured, not stand out as an obvious patch, which is part of why matching the mix and finish correctly matters as much as the structural repair itself.

Curing time varies with weather, and we allow the mortar the time it genuinely needs rather than rush a finish that will crack again within a season because it was worked or exposed too soon.

How much repointing a stack usually needs

Not every joint on a stack needs redoing, we assess the whole chimney and repoint where the mortar has genuinely failed, rather than strip and redo sound joints unnecessarily just to make the job look more thorough. This keeps the cost proportionate to what the chimney actually needs.

Areas we cover

Chimney repointing across Wisbech, Cambridge, Ely and the rest of Cambridgeshire, Norfolk, west Suffolk and south Lincolnshire.