What is lime pointing?
Pointing is the exposed face of the mortar joints between stones or bricks. In any solid-wall building constructed before the early twentieth century, that mortar was lime-based: softer and more porous than the masonry around it. This is deliberate. The joint acts as the wall's wick — moisture that enters the wall migrates to the mortar and evaporates from the joint, and any movement in the building is absorbed by the mortar rather than cracking the stone. The pointing is designed to weather and, eventually, to be renewed. It is the sacrificial element of the wall.
Lime pointing means repairing or renewing those joints with a lime mortar matched to the original — in strength, in aggregate, in colour and in the profile of the finished joint — so the wall keeps working the way it was built to.
Why cement pointing damages old walls
A large share of our pointing work is undoing well-intentioned repairs in cement. Cement mortar is harder and far less permeable than most building stone and old brick, and in a solid wall that inverts the whole system. Moisture can no longer escape through the joints, so it is forced out through the face of the masonry instead — and in frost, trapped water freezes behind the surface of the stone and spalls it away. The result is familiar across South Wales: hard grey cement joints standing proud while the sandstone or brick around them crumbles back. The wall erodes instead of the joint.
- Cement traps moisture in the wall, raising damp levels internally as well as externally
- The masonry, not the mortar, becomes the sacrificial element — stone faces spall and brick arrises erode
- Rigid cement joints crack rather than accommodate movement, letting water in behind them
- Once the stone face is lost, the damage is permanent; mortar can be renewed, masonry cannot
Careful cement removal
Removing failed cement pointing is slower and more skilled than the repointing itself, and it is where walls are most often ruined. Attack hard cement with an angle grinder and you widen every joint and scar every stone. We work with hand tools — plugging chisels, quirks and thin-bladed hacksaws — using small sharp blows along the joint, and we accept that a stubborn, well-adhered patch of cement is sometimes better left than removed at the cost of the stone around it. Joints are then raked out to a sound depth, brushed clean and dampened before new mortar goes in.
Mortar matching: aggregate, colour and joint profile
Good repointing should be hard to spot. We match new mortar to the original by examining what is in the wall: the type and grading of the aggregate, the colour of the sand, the lime binder and the strength the joint actually needs. On conservation work that can mean analysing an original sample; on most jobs it means trial mixes checked dry against the existing joints, because lime mortar lightens considerably as it cures. The joint profile matters just as much — a flush, slightly weathered or brushed-back finish that follows the stone, never the raised 'strap' or ribbon pointing that traps water on its top edge.
Mixes are chosen for the exposure and the masonry: fat lime putty mortars for soft stone and sheltered work, moderately hydraulic lime (NHL 2 or 3.5) where the wall is exposed to driving rain or frost. New pointing is protected from sun, wind and frost while it carbonates — pointing done in the wrong weather fails early, so we programme the work around the season.
Our lime pointing service
- Repointing stone and brick walls in matched lime mortar
- Careful removal of cement pointing using hand tools
- Mortar matching by eye and by sample — aggregate, colour and joint profile
- Repointing of chimneys, boundary walls, barns and outbuildings
- Deep tamped pointing and packing of eroded rubble-stone joints
- Localised patch repointing where most of the wall remains sound
When does a wall need repointing?
Not as often as people think. Weathered joints that have receded a little are usually still doing their job, and over-frequent repointing does more harm than good. The wall needs attention when mortar is soft enough to rake out with a finger, when joints are open and washing out, when vegetation has rooted in them, or when cement pointing is visibly damaging the surrounding masonry. We only repoint what needs it — sound original lime mortar is always worth keeping.
Where we work
We are based near Newport and carry out lime pointing and repointing across South Wales and the West Country — including Cardiff, Monmouthshire, Abergavenny, Hereford, Gloucester, Bristol and Swansea. For the right building we will travel further; get in touch and tell us about the wall.