- 27 Jun 2026
- 3 min read
Cement pointing on natural stone is one of the most destructive repairs a building can receive. It looks solid. It feels hard. But for Yorkshire gritstone, limestone, or sandstone — it is actively breaking the building.
Why Stone and Cement Are Incompatible
Traditional stone walls were built with soft lime mortars for a reason. Natural stone expands and contracts with temperature and moisture. Lime mortar — being softer and more flexible — moves with it. Cement does not. It is rigid and far stronger than the stone itself.
When cement-pointed stonework cycles through freeze-thaw, it cannot flex. Instead of the mortar yielding, the stress transfers into the face of the stone. The result: spalling — the face of the stone flaking away, often in large sheets. Once the stone face is lost, it cannot be restored. The damage is permanent.
How to Spot Cement Damage on Yorkshire Stone
- Mortar joints standing proud of the stone face — cement shrinks less than lime and tends to sit high
- Hairline cracks running along the junction between mortar and stone
- Stone faces that look pitted, layered or flaking, especially around joints
- Dark, damp patches that will not dry out — cement traps moisture behind it
- White efflorescence (salt deposits) migrating out from behind cement beads
Why the Wrong Repair Makes It Worse
A common response is to rake out the damaged cement and apply more cement. This repeats the problem and accelerates stone loss. Some contractors apply sealants over the top — this traps even more moisture internally. If your building is listed or in a conservation area, cement repointing may already constitute unauthorised works.
The correct specification for Yorkshire stone — particularly sandstone and gritstone — is a hydraulic lime mortar matched to the original. This requires knowledge of the wall's construction, the stone's porosity, and the exposure rating of the site. It is not a general building task.
When You Need a Specialist Inspection
If your stone building has been cement-pointed at any point — whether recently or decades ago — you need a proper building leak and damp inspection before any further work. The inspection will identify how much stone loss has occurred, whether damp is trapped behind joints, and what mortar specification is appropriate for your building and location.
NSJ carries out lime mortar repointing across Bradford, Harrogate, Ilkley, Otley and the wider West and North Yorkshire area. We specify and apply mortars that comply with BS 7913:2013 for conservation work on historic and listed buildings.
If you can see cement on your stonework, do not wait. Every freeze-thaw cycle removes more stone face. Contact us for an assessment.