Stone Pointing in Edinburgh

Edinburgh is a sandstone city, and its stone lasts far longer when the mortar between the joints is right. Repointing in lime rather than cement is the single most important decision in a stonework repair.

Why Lime, Not Cement

Edinburgh's tenements and townhouses are built largely from local and regional sandstones, a relatively soft, porous stone. In a traditional solid wall the mortar has a job beyond sticking stones together: it acts as the sacrificial part of the wall. Lime mortar is weaker and more permeable than the stone, so moisture in the wall travels out through the joints and evaporates, and any wear happens to the mortar rather than the stone. Repointing every few decades is normal and expected.

Cement mortar reverses that relationship. It is stronger and much less permeable than sandstone, so moisture that would have escaped through the joints is pushed out through the face of the stone instead. Over freeze-thaw cycles that face flakes and spalls, and because the cement is harder than the stone, it survives while the stone around it erodes. The result is a wall where the pointing stands proud in ridges and the stone has crumbled back behind it. This is why Historic Environment Scotland and Edinburgh's conservation officers are firm that traditional stone walls are repointed in lime.

Raking Out the Old Joints

Good repointing starts with careful removal of the failed mortar. The aim is to take out loose and decayed mortar back to a sound depth, generally around two to two and a half times the width of the joint, so the new mortar has enough depth to key in and is not just a thin skim over the old. Thin surface pointing fails quickly.

How you rake out matters as much as how deep. Hand tools, a plugging chisel and a quirk or hooked blade, let you follow the joint without touching the stone. Angle grinders are the classic cause of ruined stonework: they widen the joint, cut into the arrises (the crisp edges of the stone) and leave saw marks that never come out. On any wall worth keeping, and certainly on a listed building or in a conservation area, raking out is done by hand. Once the joints are open, brush and dampen them so the wall is not bone dry when the mortar goes in.

The Mortar Mix

The right mix is one that matches the existing mortar in strength, permeability and appearance. That usually means a lime mortar, either a natural hydraulic lime (NHL) or a traditional non-hydraulic lime putty or hot-mixed lime, depending on exposure and what the building was built with. A common starting point is roughly one part lime to two or three parts well-graded sharp sand, adjusted to suit the stone and the local weather, but the exact specification is a judgement based on the original mortar rather than a fixed recipe.

Binder

Natural hydraulic lime (NHL 2 or 3.5 for most Edinburgh work) or a traditional lime putty or hot-mixed lime, chosen to be no harder than the stone.

Aggregate

Well-graded sharp sand, selected to match the colour and grain of the original mortar. The sand largely controls the final colour, so matching it is what makes a repair blend in.

Ratio

Around 1 part lime to 2 to 3 parts sand as a common range, adjusted for exposure. Softer, more permeable mixes suit sheltered elevations; slightly more hydraulic mixes suit exposed ones.

Colour and texture come from the aggregate and the finish, not from adding pigment or cement. A repair that matches the original sand and is finished flush or slightly back from the stone face will weather in and become almost invisible. Proud, smoothed "strap" or ribbon pointing over the face of the stone is both wrong technically and obvious visually.

Finishing, Weathering and Curing

The joint is normally finished flush with, or just slightly recessed from, the stone, then lightly tamped and brushed once it has taken up, which knocks back the surface and exposes the aggregate so it matches the weathered look of the original. Lime needs to cure slowly and stay damp to gain strength, so freshly pointed work is protected from sun, wind and rain with damp hessian and sheeting, and misted if it starts to dry too fast. Lime work is not done in freezing conditions, so avoid pointing in the depths of an Edinburgh winter, roughly from late autumn to early spring, when frost can destroy the mortar before it has set.

Well-executed lime pointing has a useful trick: fine cracks tend to self-heal as free lime recrystallises, which is one reason a lime-pointed wall can go for decades between repairs while staying weathertight.

When to Call a Specialist

Small areas of pointing at ground level are within reach of a competent DIY owner willing to learn lime technique. Bring in a specialist stonemason once the work involves working at height, matching mortar on a prominent elevation, or any listed building or conservation-area property, where getting the mix and method wrong can mean an enforcement problem as well as a poor repair. Repointing a listed building generally needs listed building consent, and inside a conservation area it can need planning permission, so check before starting. Our guides to lime plaster and harling and roughcast cover the related lime finishes on the same walls, and Traditional Finishes gives the wider picture.

Last reviewed: 2026-07-10