Should old stone and brick walls be pointed with lime or cement?

For an old stone or brick wall, lime mortar is usually the starting point when repointing is genuinely needed. The new mortar should suit the existing masonry and the wall's exposure; there is no universal mix to copy from another house. Hard cement pointing can make old masonry deteriorate faster, but that does not mean every cement patch should be stripped out. First decide whether the joints need repair at all, then ask someone experienced in traditional buildings to specify the work.

Why the mortar needs to suit the wall

Pointing is the mortar visible between bricks or stones. Its job includes helping keep weather out. In older masonry, lime mortar can be more permeable than the units around it, so moisture and some weathering tend to affect the joint instead of concentrating in the stone or brick. The mortar is intended to be the part that can wear and be renewed. A hard cement joint can change that balance, leaving the masonry itself to bear more frost and salt action.

That is why a neat, hard finish is not automatically a better repair. SPAB warns that routine hard cement pointing on old buildings can speed deterioration of brick and stone. Lime-based materials can also accommodate gentle movement in traditional fabric. None of this means that any bag labelled lime will do. Lime comes in different forms and strengths, and a stronger mortar may be less permeable and flexible. Material, strength, colour, texture and finish have to be considered for the wall in front of you.

Does the wall actually need repointing?

Do not repoint simply because old mortar feels soft or looks weathered. SPAB advises that repointing is premature until mortar has weathered back substantially into the joint or is very loose. Wear is often uneven, so a local repair can be more appropriate than doing a whole elevation. Unnecessary repointing can damage the edges of the brick or stone and remove useful clues about the building. The safest first question for a contractor is not which mortar to use, but which joints have failed and why.

Take a careful look from ground level. Are joints open or loose, is rain entering, or is there a small area of genuine loss? If the wall is damp, also check the wider water route: overflowing gutters, exposed details and drainage may matter more than the pointing. A new mortar cannot correct a separate leak. If the pattern is unclear, an independent, suitably qualified surveyor with traditional-building experience can identify the cause before any wall is opened up.

What if there is cement pointing already?

A hard patch beside older lime joints is worth assessing, particularly if adjacent stone or brick is deteriorating. But taking hard mortar out can damage the edges of the masonry. SPAB says removal should be attempted only after a trial shows it can be done without further damage; otherwise it may be better to leave it until the mortar works loose. Resist the temptation to chip out sound joints just because they look different. Ask for the condition of the masonry and the risks of removal to be explained before agreeing to work.

Pennine pointing in Yorkshire and Lancashire

On a Pennine stone terrace, a hard patch repair may sit right beside older, softer lime joints. That difference can alter where moisture leaves the wall after rain and where weathering shows up. Look at the condition of the stone next to the patch, the more sheltered original joints and the exposure of that particular elevation. A gable that takes the weather calls for an assessment of its actual conditions, not a mortar choice copied from the front wall or the house next door. Localised, compatible repair may be all that is needed.

How a sound repair is chosen

Where repointing is necessary, a specialist should examine surviving original mortar, often easiest to see in a sheltered place such as under the eaves. SPAB recommends matching material and finish where possible and taking exposure into account. Samples and trial panels can show how the proposed mortar and joint will look and behave before work spreads across a wall. The aim is a repair compatible with the existing brick or stone, rather than the hardest possible mix or a fashionable joint shape.

The work itself also needs suitable conditions. New pointing must be protected from frost, rain and rapid drying, and poor preparation can lead to failure. Ask the person doing the work how they will protect it and which joints they intend to leave alone. If the building has historic finishes or is listed, involve someone with the relevant conservation experience before changing the appearance or fabric. For most readers, the practical next step is simple: establish whether the mortar has really failed, trace any damp to its source, and have the repair specified for that wall.

This page gives general information, not legal or medical advice. For your own situation, use the organisations listed under "Where this comes from" at the foot of the page.