CareHomeDeskCareHomeDeskRepointing an older building with the wrong mortar can cause more damage than leaving it alone. What 'like for like' actually means, and why Historic England's own guidance says less repointing is often the right answer.
Most care home buildings constructed before around 1919, and many later buildings built in a traditional style, use lime mortar rather than cement. The mortar is deliberately more permeable and softer than the brick or stone it sits between, which lets moisture entering the wall escape through the joints rather than through the masonry units themselves -- the mortar is the sacrificial part of the wall, eroding gradually over decades so the brick or stone does not have to. This is the single fact that should drive every repointing decision on an older building: matching the mortar's characteristics to what's already there matters more than how neatly the joint is finished.
A hard, dense cement mortar is far less permeable than traditional lime mortar and than most older brick or stone. Repointed with cement, a wall that used to let moisture evaporate evenly through its joints is instead forced to push that moisture out through the face of the brick or stone itself, since the new mortar won't let it through. The result, well documented by Historic England, SPAB and specialist repointing contractors alike, is spalling, frost damage to the masonry face, trapped damp and accelerated long-term decay -- the repair intended to protect the wall ends up damaging it faster than leaving deteriorated original mortar in place would have.
Historic England's own guidance on repointing (Repointing Brick and Stone Walls: Guidelines for Best Practice) is explicit that comprehensive repointing of an entire elevation is rarely necessary. Sound original mortar should be left undisturbed -- it's often part of the building's genuine character as well as being structurally fine -- and work should be targeted at the sections that are actually failing: joints eroded back to a depth roughly equivalent to the joint's own width, or areas affected by a specific, identifiable problem such as a leaking gutter or downpipe. A survey that recommends repointing an entire wall or elevation without distinguishing sound mortar from failed mortar is worth querying before it's approved.
Repointing addresses a symptom -- eroded or failed mortar -- not necessarily the reason the mortar failed there and not elsewhere. A leaking rainwater pipe, a failed roof detail, or rising damp will continue degrading new mortar exactly as it degraded the old, so the source of water ingress should be identified and fixed before repointing work starts, not scheduled alongside it as an afterthought. Repointing over an unresolved cause is money spent on a repair that's already failing again by the time it's finished.
A repointing specification for an older or traditionally-built care home should specify a lime-based mortar (commonly a Natural Hydraulic Lime, NHL, mix) matched in strength and appearance to the original rather than a generic sand:cement mix, with the exact mix and sand colour/texture confirmed against a sample of sound existing mortar before work starts. It should require hand tools for raking out defective joints wherever practical, since power tools and grinders risk damaging the arrises of the surrounding brick or stone -- guidance from conservation specialists consistently flags this as one of the most common ways a repointing job damages the very masonry it's meant to protect. Where existing cement pointing genuinely cannot be removed without damaging the masonry beneath it, established guidance is that it may be better left in place than removed at the cost of the original fabric.
CareHomeDesk gives you compliance checklists, maintenance logs, and contractor management tools built around exactly this kind of knowledge.