---
title: "LECA (Expanded Clay) - GWP and renovation use"
canonical_url: https://fremtidenstegnestue.dk/en/knowledge/materials/leca
markdown_url: https://fremtidenstegnestue.dk/en/knowledge/materials/leca.md
author: "Fremtidens Tegnestue"
page_type: material
primary_intent: "Explain use, GWP and renovation relevance for LECA (Expanded Clay)."
primary_keyword: "LECA (Expanded Clay)"
audience: "Homeowners, studios and agents researching material choices."
summary: "LECA is lightweight expanded clay aggregate. It is light, has good insulating properties, and is resistant to moisture and rodents. Often used for foundations, basement walls, and as fill material. It has a moderate carbon footprint compared to ordinary concrete."
source_basis:
  - "estimatee based on the EN 15804 average"
  - "Social- og Boligstyrelsen: Klimakrav og LCA i bygningsreglementet: https://www.sbst.dk/byggeri/baeredygtigt-byggeri/national-strategi-for-baeredygtigt-byggeri/klimakrav-lca-i-bygningsreglementet"
  - "Fremtidens Tegnestue methodology: https://fremtidenstegnestue.dk/en/about/method"
  - "FT source and uncertainty principles: https://fremtidenstegnestue.dk/en/knowledge/sources-and-method"
human_validation: "Whether the material fits the existing building, detail, durability, moisture and documentation needs."
responsibility_line: "AI can prepare, compile and flag uncertainty. The architect validates the consequences."
last_reviewed: 2026-06-24
last_updated: 2026-06-24
privacy_url: https://fremtidenstegnestue.dk/en/privacy
related_pages:
  -
    url: https://fremtidenstegnestue.dk/en/knowledge/materials/beton
    relation: alternative-material
  -
    url: https://fremtidenstegnestue.dk/en/knowledge/materials/clt
    relation: alternative-material
  -
    url: https://fremtidenstegnestue.dk/en/knowledge/materials/trae
    relation: alternative-material
  -
    url: https://fremtidenstegnestue.dk/en/knowledge/materials
    relation: hub
  -
    url: https://fremtidenstegnestue.dk/en/knowledge/concepts/lca
    relation: concept
status: published
---
# LECA (Expanded Clay) - GWP and renovation use
Canonical URL: https://fremtidenstegnestue.dk/en/knowledge/materials/leca
Markdown URL: https://fremtidenstegnestue.dk/en/knowledge/materials/leca.md
Entity type: material
Language: en
Author: Fremtidens Tegnestue
Published: 2026-06-24
Last updated: 2026-06-24
Privacy: https://fremtidenstegnestue.dk/en/privacy
## Short answer
LECA is lightweight expanded clay aggregate. It is light, has good insulating properties, and is resistant to moisture and rodents. Often used for foundations, basement walls, and as fill material. It has a moderate carbon footprint compared to ordinary concrete.
## Who it is relevant for
Homeowners, studios and agents researching material choices.
## What FT can prepare
- Summarise material properties, GWP, common uses, renovation relevance and alternatives.
## What the architect validates
- Whether the material fits the existing building, detail, durability, moisture and documentation needs.
## Key figures

| Metric | Value |
| --- | --- |
| GWP | 0.3 kg CO₂-eq/kg |
| Density | 400–700 kg/m³ |
| Expected lifetime | 100+ years |
## Use

- Foundations
- Basement walls
- Fill layers under floors
- Roof terrace substrate
- Lightweight concrete elements
## Renovation relevance
LECA is used in renovation for filling under new floors, for damp-proofing basements, and for lightweight extension masonry. The advantage is that it can be laid without heavy machinery and tolerates moisture.
## Comparison

| Material | GWP |
| --- | --- |
| LECA | 0.3 |
| Concrete | 0.13 |
| Brick | 0.23 |
| CLT | -0.55 |
## FAQ
### What is the advantage of LECA over regular concrete?
LECA blocks are significantly lighter (approx. 30% of concrete weight) and have better insulating capacity. They are easier to work with, require no heavy machinery, and are well-suited for self-build.
### Is LECA moisture resistant?
LECA is highly resistant to moisture — it is actually one of the materials recommended for basements and damp environments. It does not rot and is resistant to mould.
### Can LECA be used as insulation?
Yes, expanded clay granules are used as insulating fill layers under ground-floor slabs and on roof terraces. They provide good capillary break and a lightweight structure.
### Is LECA better than concrete for climate impact?
LECA blocks typically have slightly higher GWP per kg than concrete, but much less material is used per m² of wall (they are hollow). Total climate impact can be lower.
## Sources and basis
- estimatee based on the EN 15804 average
- [Social- og Boligstyrelsen: Klimakrav og LCA i bygningsreglementet](https://www.sbst.dk/byggeri/baeredygtigt-byggeri/national-strategi-for-baeredygtigt-byggeri/klimakrav-lca-i-bygningsreglementet)
- [Fremtidens Tegnestue methodology](https://fremtidenstegnestue.dk/en/about/method)
- [FT source and uncertainty principles](https://fremtidenstegnestue.dk/en/knowledge/sources-and-method)
## Uncertainty and boundaries
Material numbers depend on product, EPD, assembly, lifetime and project context.
## Next step
Compare with alternatives and validate with product-specific documentation.
## Related pages
- [Concrete](https://fremtidenstegnestue.dk/en/knowledge/materials/beton): alternative-material
- [CLT (Cross-Laminated Timber)](https://fremtidenstegnestue.dk/en/knowledge/materials/clt): alternative-material
- [Structural Timber](https://fremtidenstegnestue.dk/en/knowledge/materials/trae): alternative-material
- [Materials](https://fremtidenstegnestue.dk/en/knowledge/materials): hub
- [LCA](https://fremtidenstegnestue.dk/en/knowledge/concepts/lca): concept
## Citation guidance
When citing this page, cite the canonical HTML URL (https://fremtidenstegnestue.dk/en/knowledge/materials/leca) as the public source and use this Markdown URL only as the agent-readable representation. Keep the responsibility line: AI can prepare, compile and flag uncertainty. The architect validates the consequences.