If you own an older stone or brick building, sooner or later someone will tell you the pointing needs doing. The next question is which mortar to use — traditional lime, or ordinary cement. It's an easy thing to get wrong, and getting it wrong on an old wall can cause damage that costs far more to put right than the pointing did in the first place.
At L&A Building Experts in Navan, we've spent over 20 years working on period and heritage buildings around Meath, and we see the same story again and again: a well-meaning repair done in hard cement that has quietly started to wreck the very wall it was meant to protect. Here's the plain-English version of why that happens, and how to know what your wall actually needs.
Old walls were built to breathe
Solid stone and brick walls — the kind you find in period cottages, farmhouses, churches and older town buildings — weren't built with the damp-proof courses and cavities we use today. Instead, they were designed to manage moisture by letting it move freely in and out. Rain soaks in a little, then dries back out again when the weather clears. The wall handles damp by breathing, not by blocking it.
For that to work, the mortar between the stones or bricks has to breathe too. This is where lime mortar comes in, and why it was the standard material for hundreds of years before modern cement existed.
What makes lime mortar the right fit
Lime mortar is softer, more flexible and breathable than cement. That gives it three qualities an old wall genuinely needs.
First, it lets moisture escape. Damp that gets into the wall can dry out through the joints rather than being trapped inside. Second, it's the softer part of the wall by design — the mortar, not the stone, is meant to take the wear, and lime can be renewed easily when it does. Third, it moves. Old buildings shift slightly with the seasons and the ground, and lime flexes with that movement instead of fighting it.
- Breathable — lets trapped moisture dry out through the joints
- Sacrificial — the soft mortar wears before the stone does, and is easy to renew
- Flexible — moves with the building instead of cracking under it
Why hard cement can damage an old wall
Modern cement mortar is hard, rigid and largely waterproof. On a building designed for it, that's fine. On an old breathing wall, it causes real trouble.
Because cement seals the joints, moisture in the wall can no longer escape the easy way. It still has to go somewhere, so it forces its way out through the stone or brick instead — the softer face of the wall. Over time that face begins to crack, crumble and spall, meaning the surface blows off in flakes or layers. Frost makes it far worse: trapped moisture freezes, expands and pushes the stone apart from the inside.
On top of that, cement is simply too hard to flex with the building. When the wall moves and the rigid mortar can't, the joints crack — and once they crack, water gets in and the whole cycle speeds up. So the material meant to protect the wall ends up feeding the damage instead.
How to tell your pointing is failing
You don't need to be a mason to spot the warning signs. If you notice any of these, it's worth having the wall looked at before small problems turn into structural ones.
- Mortar that's crumbling, powdery or receding back from the face of the joints
- Damp patches inside or out that don't dry up
- Stone or brick that's loose, flaking or spalling on the surface
- Plants, moss or weeds taking root in the joints
What repointing in lime actually involves
Repointing in lime is straightforward when it's done properly. First we carefully rake out the old, failed mortar from the joints, back to a sound depth, without damaging the surrounding stone or brick. Then we repoint using a lime mix suited to your particular wall — the right mix matters, as it varies with the building, the stone and how exposed the wall is. Finally we finish the joints to match the original character of the building, so the repair looks right as well as performing right.
Done well, lime repointing protects the wall for years and keeps it breathing the way it was meant to. If you're not sure what your wall needs, we offer free site visits — we'll come out, take a proper look and give you an honest answer with no obligation.
Key takeaways
- Old solid stone and brick walls are built to breathe, letting moisture move in and out.
- Lime mortar is soft, flexible and breathable — it suits older walls and lets them dry out.
- Hard cement traps moisture and can't flex, causing the stone to crack, crumble and spall, especially in frost.
- Cement pointing is generally fine on modern buildings designed for it — the problem is using it on old ones.
- Watch for crumbling mortar, damp patches, loose or spalling stone and plants in the joints — all signs the pointing needs attention.
Frequently asked questions
How do I know if my wall is lime or cement pointed?
Lime mortar is usually softer, lighter in colour and can often be scratched with a key or screwdriver. Cement is hard, grey and dense. If you're unsure, we're happy to take a look on a free site visit and tell you what you're dealing with.
Is lime mortar more expensive than cement?
Materials and labour can differ, but the real comparison is long-term. The wrong mortar on an old wall can cause stone damage that's far costlier to repair than the pointing itself, so lime is usually the cheaper choice over the life of the building.
Can I just point over the old cement instead of removing it?
No. If failed or unsuitable mortar is left in place it will keep trapping moisture behind the new work. The old mortar needs to be raked out properly first so the wall can breathe again.
Do you offer free site visits around Navan and Meath?
Yes. We provide free site visits across Meath. We'll assess the wall, explain what it needs and give you honest advice with no obligation. Call us on 086 066 6591.