Limecrete Floors for Old and Stone Houses

Why old houses need a breathable floor

Old stone and solid-wall houses were built without damp-proof membranes. Moisture from the ground escapes through the floor and walls. Seal the floor with concrete and a membrane, and that moisture has nowhere to go but up into the walls, where it shows up as damp, flaking plaster and rotting skirting boards.

What limecrete is

Limecrete is a lime-based concrete. It's usually laid over a layer of loose insulating aggregate, such as expanded clay or recycled foamed glass, which stops ground moisture wicking up while still letting the floor breathe. A lime screed can then give the finished, level surface.

Underfloor heating in a limecrete floor

Underfloor heating can go into a limecrete floor, and it suits old houses that are slow to heat. The pipes sit within the lime layers.

Protected structures

If the house is a protected structure, the floor build-up may need sign-off from the conservation officer. We'll work to their spec or your architect's.

Typical limecrete floor build-up

• Dig out to the right depth, without undermining old walls
• Breathable membrane over the ground
• Layer of loose insulating aggregate, such as expanded clay or recycled foamed glass
• Limecrete slab, with underfloor heating pipes if you're having them
• Lime screed or a breathable finished floor

Depths depend on the house, the ground and the insulation you choose.

What to avoid in an old house

• Cement-based concrete or screed laid wall to wall
• Plastic damp-proof membranes under the floor
• Sealed floor coverings like vinyl over a lime floor
• Cement plaster repairs at the base of old walls

All of these stop the building breathing and push moisture into the walls.

Combining old and new

Plenty of renovations add a modern extension to an old house. The extension can have a standard insulated slab and underfloor heating screed, while the original rooms get limecrete. The detail where the two floors meet matters, so we'll go through it with you.

Is limecrete right for my house?

• Yes, usually: stone cottages, farmhouses and solid-wall period houses
• Yes, usually: houses already showing damp at the base of the walls
• Probably not needed: modern cavity-wall houses with a damp-proof course
• Ask us: extensions on old houses, where the two floors meet

More on our lime screed and limecrete work.

From JAM Floor Screeding, Portlaoise. Over 20 years laying screed across Leinster. Figures here are typical guidance; your floor's spec and the manufacturer's data sheet always come first.