Lime mortar and repointing older Wiltshire homes

Wiltshire has a huge amount of older property: Georgian and Victorian brick in Devizes and Marlborough, Bath stone in Corsham, Calne and Bath, and brick, flint and timber-framed cottages in the villages. Almost all of it was built with lime mortar, and it needs lime to stay healthy.

Why lime matters

Older solid walls do not have a cavity. They handle moisture by absorbing it and letting it dry out again through the joints and the face of the wall. Lime mortar is softer and more breathable than the brick or stone around it, so moisture escapes through the mortar, and any movement or wear happens in the joint, which can be repointed, rather than in the masonry, which is much harder to replace.

What cement pointing does to an old wall

Cement mortar is hard and far less breathable. When it is used to repoint an old wall:

• Moisture is trapped behind it and has to escape through the brick or stone instead
• Frost then pushes the face off the brick or stone, which is known as spalling
• Damp can appear inside the house
• The hard joints crack away from the softer masonry, letting even more water in

You will often see the damage on older Wiltshire houses: crisp grey cement joints standing proud of bricks whose faces have crumbled away around them. Bath stone is especially vulnerable because it is soft and porous.

What good repointing involves

Repointing is slow, careful work, and the preparation matters more than the pointing itself.

• Raking out. Old mortar is removed by hand to a sound depth, typically about twice the height of the joint, without damaging the edges of the brick or stone.
• Choosing the mix. Lime mortars range from soft lime putty mixes to natural hydraulic limes of different strengths. The right choice depends on the masonry, how exposed the wall is, and what was used originally. The sand is chosen to match the colour and texture of the existing mortar.
• Preparing the joint. The joint is cleaned out and dampened so the wall does not suck the moisture out of the new mortar.
• Pointing. Mortar is pressed in firmly in layers and finished to match the original joint profile, often flush or slightly recessed rather than raised.
• Curing. Lime cures slowly. Fresh work is protected from frost, strong sun, wind and rain while it hardens, so lime pointing is best avoided in freezing weather.

Listed buildings and conservation areas

If your home is listed, changing the mortar or the style of pointing can need listed building consent. In conservation areas, such as central Devizes, Marlborough and Bath, the council will expect sympathetic materials. Our guide to planning permission and building regulations covers how these designations affect building work.

Lime beyond pointing

The same principle applies to the rest of an older building. Lime render and lime plaster let solid walls breathe where modern gypsum plaster and impermeable renders can trap damp. Lime plastering and traditional rendering are part of our plastering and rendering service.

Old boundary walls benefit too. Rebuilding a historic wall with its original bricks and a lime mortar keeps its character and lets it last. See our boundary walls page.

Getting it done

Repointing is one of our core bricklaying services. We work on period brick and stone across Devizes, Marlborough, Corsham and Bath, matching mortar colour, texture and joint profile to the original.

If your pointing is cracked, crumbling or has been patched in cement, get in touch for a free site visit and advice.