When the ground floor of an old house needs replacing, the usual modern answer is a concrete slab over a plastic damp-proof membrane. In a new house, that works well. In a building with solid walls and no damp-proof course, it can cause real problems. Limecrete is the traditional-style alternative.
Why concrete can cause damp in old buildings
Traditional floors of flagstones, brick or earth let a little ground moisture rise and evaporate across the whole floor area. A concrete slab with a membrane stops that completely. The moisture still has to go somewhere, and it moves sideways to the edges of the floor and up into the base of the walls. The result is often rising damp, tide marks and decay at skirting level that never used to be there.
How a limecrete floor works
A limecrete floor is built in layers:
- A base of free-draining, insulating aggregate, which stops moisture rising by capillary action and keeps the floor warmer.
- A slab of limecrete, a mix of lime and aggregate, which is breathable and very slightly flexible.
- A breathable finish, such as flagstones, clay tiles, brick or timber.
Any moisture can evaporate evenly across the floor, rather than being pushed into the walls, and the building can manage moisture the way it was designed to.
Benefits of limecrete
- Helps prevent damp being driven into the base of solid walls.
- Insulated, so the floor is warmer underfoot.
- Works well with underfloor heating.
- Suits the character of period and listed buildings.
- A lower carbon footprint than a cement-based slab.
Things to consider
Limecrete cures more slowly than concrete, so it needs time before the final floor goes down, and it needs protecting while it cures. The floor finish has to be breathable too, as a sealed or impermeable finish would undo the benefit. And as with any floor replacement in an old building, the wall footings need care when the ground is dug out.
Find out more
If you are planning to replace a floor in an old building, read more about our limecrete flooring or get in touch for a free site visit.
