Limecrete Floor Slab
Hydraulic lime slab laid over a lightweight expanded clay sub-base. Vapour-open, so it lets a solid-walled building dry downward instead of pushing damp into the walls.
Carbon and evidence
How This Is Made
An Environmental Product Declaration is issued by a manufacturer against a declared unit. This record has neither, so it states sourced facts about process and provenance instead of a carbon figure.
Standard breathable-floor buildup in UK heritage and solid-wall retrofit
Process
Feedstock
Mineral
Natural hydraulic lime over expanded clay (LECA) or foamed recycled glass
Process heat
Calcined
Lime is burnt at roughly 900C, and the LECA sub-base is itself kiln-expanded. This is NOT a low-process material — its case rests on moisture behaviour in solid-walled buildings, not on embodied carbon.
Binder
Lime
Fabrication
Site-formed
Sourcing: national
Who Builds It
Trained contractor
Limited UK availability
Slow cure and a wet trade; sequencing against other finishes is the practical difficulty
End Of Life
Monolithic
Broken out at end of life; the LECA sub-base is separable and reusable
Maintenance: As a lime floor: no sealants, breathable finishes only
Specification Risk
What a specifier has to resolve before this can be built.
- Certification
- No Agrément for the buildup; component materials are certified individually
- Fire
- Non-combustible
- Warranty
- Workmanship only
- Insurance
- Not normally an issue
- Supply
- Materials are readily available; experienced installers less so
Read This Honestly
- •Lime is calcined at high temperature. Carbonation reabsorbs some of that CO2 over time — state both, net neither.
- •Specified for moisture performance, not for carbon. Nothing here claims it is lower-carbon than a concrete slab.
Design & Specification Notes
Hydraulic lime slab laid over a lightweight expanded clay sub-base.
Material Note
The standard answer where a concrete slab would trap moisture in a solid-walled building. The lime binder is calcined at high temperature and reabsorbs CO2 as it cures — two opposing effects that should be stated separately, never netted.
Typical Uses
- •Primary flooring
- •High-traffic circulation
- •Work areas
Key Performance
Hard-wearing surface for high footfall.
Specification Actions
- •Confirm the build-up suits the wall construction; the point of limecrete is vapour-openness, and a sealed finish defeats it.
- •Check the LECA or recycled-glass sub-base depth against the insulation target.
- •Do not specify over a damp-proof membrane; that reverts it to a concrete slab with extra steps.
Indicative Health & Indoor Air
- •dust
Wet lime is caustic during placement. Inert once cured.
Products in this category
6 products from 6 manufacturers · 25 in this category. Ordered by the evidence each record holds, never by commercial standing.
Specification
- Finish
- Limecrete over LECA, breathable
- Service life
- 60 years