If you own an older stone property in Derbyshire — a cottage at Old Brampton, a terrace in the pit villages, anything toward the Peak fringe — the question of lime versus cement mortar isn't academic. It's the difference between a repair that lasts and one that actively damages your building. Get it wrong and you'll watch the stone faces pop off over a few winters.
What mortar actually does
Mortar's job is to hold the units together and to be the part that gives — the sacrificial layer that takes the weather so the stone or brick doesn't. The mortar should always be softer than the material it's pointing. When the mortar is softer, moisture evaporates out through the joints, the building breathes, and when the weather eventually does for the mortar, you repoint — not rebuild the wall.
Why cement on soft stone is a mistake
A hard cement mortar is stronger than soft Derbyshire stone and older brick. When moisture gets in — and it always gets in — it can't evaporate through the hard cement, so it gets trapped. Come winter, that trapped moisture freezes, expands, and the only thing that can give is the stone face itself. The result is spalling: the front of the stone pops off, leaving a rough, recessed surface that gets worse every year.
I've seen plenty of older property across Derbyshire ruined by a previous "repointing" in cement. The mortar sits there, hard and proud, looking neat — and the stone around it crumbles. It's the exact opposite of what pointing is meant to do. The mortar was meant to sacrifice itself to protect the stone; instead the cement sacrificed the stone to protect itself.
When cement is the right choice
Cement mortar has its place. On newer brickwork — post-war semis, modern estates, anything built with hard engineering brick — a sand-and-cement mix is appropriate because the brick is hard enough to take it. Ridge tiles on a tiled roof are bedded in sand-and-cement. Cement is not wrong; it's wrong on the wrong material.
How to tell which you need
The rule of thumb is simple: if the building is stone or soft, old brick, use lime. If it's hard modern brick, cement is fine. A quick test — if you can scratch the brick or stone surface with a knife or a coin, it's soft, and lime is the answer. If the original mortar is soft and chalky and comes out easily, the building was built with lime and wants to stay that way.
Across the Peak fringe — Cutthorpe, Old Brampton, Holymoorside, out toward Barlow and Holmesfield — the property is stone-built and almost always wants lime. The conservation character of those villages means it's not just a preference, it's the right thing for the fabric.
Lime costs more — and it's worth it
Lime mortar is slower to work with and the material costs more, so a lime repoint is dearer than a cement one per square metre — roughly £40 to £70 per square metre for stone, more than the equivalent cement job. But it's the only job that won't need undoing. A cement repoint on soft stone will start spalling the brickwork within a few years and cost far more to put right than doing it properly once.
The honest version
There are firms that'll repoint your stone cottage in cement because it's quicker and cheaper, and because the customer doesn't know to ask. There are firms that'll specify lime on a modern brick semi because it sounds artisanal and justifies a higher price. Neither is honest. The right mortar is the one that serves the building in front of you — lime on the soft and the old, cement on the hard and the new — and the right roofer tells you which yours is before they start, not after.
If you've got older stone property in Derbyshire and you want pointing done the way it should be, ring 07949 348947. We'll tell you honestly whether yours is a lime job or a cement job, and quote it accordingly.