What Is Limecrete?
Limecrete is a floor slab made with lime as the binder instead of cement, usually mixed with a lightweight aggregate such as expanded clay and laid over a layer of insulation.
The important difference is that limecrete breathes. Moisture can pass up through it and evaporate rather than being sealed underneath. That is the whole point of the material, and it is why it keeps coming up on older Irish properties.
Most houses built before roughly 1940 have solid stone or brick walls, no damp proof course and no membrane under the floor. They were built to let moisture move through the structure and dry out. Limecrete works with that. Concrete works against it.
Pros and Cons
The Pros
It does not trap moisture. Ground moisture that used to rise through the old floor can still escape. In a sealed concrete floor it has nowhere to go and moves sideways into the walls instead.
It works with underfloor heating. Pipes go into the slab as normal, over the insulation layer, so you get a modern heated floor in an old building.
It suits lime plaster and traditional finishes. If the walls are being lime plastered, the whole building keeps working the same way.
Lower embodied carbon. Lime is fired at a lower temperature than cement and reabsorbs carbon dioxide as it cures.
The Cons
It is slower. Limecrete cures over weeks rather than days and needs to be kept damp and protected while it does. On a tight programme that is a real cost.
It costs more. Expect to pay noticeably more per square metre than a standard concrete slab once the insulation layer is included.
Fewer crews can lay it properly. It is not difficult, but it is not concrete, and curing is where most failures happen.
It is softer. Fine for a domestic floor. Not the right choice for a workshop floor carrying heavy point loads.
How Does It Compare to Concrete?
Concrete is cheaper, faster and stronger. On cost, a concrete slab typically runs from around €60 to €90 per square metre installed, while a full limecrete build up with insulation is more commonly in the €110 to €160 range. Site access, dig depth and whether an old floor needs breaking out all move those figures, so treat them as a starting point rather than a quote.
On strength, concrete wins comfortably. On programme, concrete wins again, days versus weeks. On availability of crews who can lay it properly, concrete wins.
Concrete loses on one thing only, and it is the thing that matters in an old house. It seals the floor. In a modern build with a damp proof membrane and cavity walls, that is exactly what you want. In a solid walled cottage with no membrane, that sealed floor pushes moisture into the walls, and you get rising damp on walls that were dry for two hundred years.
That single difference decides almost every case.
When to Choose Limecrete
- The property is pre-1940 with solid stone or brick walls
- There is no damp proof course
- You are using lime plaster or other breathable finishes elsewhere in the build
- Damp problems have appeared in the walls after previous renovation work
- It is a protected structure or a conservation-led project
- The programme has room for a slower cure
When to Choose Concrete
- It is a new build or a modern cavity wall house with a damp proof membrane
- The floor needs to carry heavy loads, such as a garage or workshop
- The programme is tight and the floor is on the critical path
- The budget is fixed and limecrete would push the project over it
- An extension is being tied into an existing modern slab
Conclusion
Limecrete is the right choice for a specific type of building and the wrong choice for most others. It is not a better floor than concrete, it is a different floor solving a different problem.
The building itself tells you which one you need. If it was built to breathe, seal it and you will pay for it in damp walls within a couple of winters. If it was built sealed, limecrete is an expensive answer to a problem you do not have.
Anyone recommending limecrete for a modern build, or concrete for a period cottage, has not looked at the property properly.
Talk to Us About Your Floor
We work on period and modern properties across Meath and the surrounding counties. If you are not sure which build up your floor needs, get in touch and we will look at the property and tell you straight.
