The product
A pre-mixed, pre-pigmented clay plaster laid in strata at around 7 to 10 mm, so an interior wall reads as monolithic rammed earth on a conventional substrate. Every specification is custom developed — there is no standard colourway.
Where it is used
- Interior walls and ceilings where rammed earth is wanted but in-situ construction is impractical — city-centre sites, refits, upper floors
- Feature walls and full-room treatments
- Fixed furniture
Substrates
- Gypsum plasterboard
- Masonry and blockwork
- Wood fibre board and wood wool carrier board
- Plywood-reinforced gypsum backing board, suitably primed
- Other substrates may require a backing coat — refer to Clayworks Design Details
Application data
Coverage, thickness, mix and cure, as declared by the manufacturer. Site conditions in the Gulf sit at the top of most of these ranges — allow for it in the programme.
| Supply | 25 kg bags of dried plaster, in recyclable or compostable bags |
|---|---|
| Applied thickness | Around 7 – 10 mm |
| Coverage | 1.2 m² nominal per 25 kg bag at 10 mm |
| Drying | 2 – 3 hours per layer, depending on temperature and humidity |
| Ancillary products | Clayworks Wall Primer and Clayworks Glaze |
| Composition | Unfired clays blended with natural minerals and pigments |
| Colour | Custom developed per project. UV resistant, through-pigmented. |
Performance data
Every figure below is reproduced from the manufacturer's own technical data sheet, with the test standard it was measured against. The sheet itself is in the download section.
| Property | Result | Standard |
|---|---|---|
| Surface spread of flame | Class 1 | BS 476-7:1997 |
| Fire propagation | I = 0.5, i₁ = 0.0 — satisfies Building Regulations Class 0 | BS 476-6:1989 + A1:2009 |
| Noise reduction coefficient | 0.20 – 0.25 NRC depending on backing board | BS EN ISO 354 |
| Impact | Impact diameter < 15 mm | BS EN 520 |
| Moisture buffer value | 1.28 — measured at 9× painted plasterboard | University of Bath figures |
| Light reflectance value | Tested; data per colour on request | BS 8493:2008 + A1:2010 |
| VOC | No detected VOCs or formaldehyde in emissions testing to the standards named | Clayworks VOC emissions certificates, EN 16516 / ISO 16000-6 |
| Embodied carbon | 0.048 – 0.068 kg CO₂e/kg | LCA stages A1–A3 |
| Material safety | No asbestos, lead, PCBs, mercury, PFCs, flame retardants, phthalates or isocyanates | Clayworks fundamental material safety |
| Mass | Physical mass of clay plaster 20.6 kg/m², about 2.5× gypsum plaster at 8 kg/m² | Research by Tom Morton et al, cited by Clayworks |
| End of life | Recyclable, compostable and re-usable; product and packaging compostable at all lifecycle stages | Clayworks data sheet |
Where not to use it
The limits are as much a part of the specification as the performance. Everything here is stated on the manufacturer's data sheet.
- Cannot be applied directly onto wood, including plywood, MDF or OSB
- Not suitable for floors
- Appropriate for bathrooms but not wet or shower areas
- Not advised on doors or items that will be moved
- Application by an approved plasterer only
Rammed earth finish: Clayworks Rammed Earth Finishes, applied 7–10 mm in strata over Clayworks Wall Primer on the substrate scheduled, colour and strata rhythm to the mock-up approved by the Architect. Fire performance to BS 476-7 Class 1 and BS 476-6 (I = 0.5, i₁ = 0.0). Applied by an approved plasterer. Clayworks Glaze to surfaces scheduled to be wiped clean.
Square brackets mark the choices that belong to the project. Send us the finishes schedule and we will return the clause completed, with the sample and mock-up programme against it.
Documents
Every document is the manufacturer's own, reproduced in full and unaltered under our cover. Free to download, no form.
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Rammed Earth Finishes Rammed earth · Technical data sheet · 7 pp · 1.9 MBDownload (PDF, 1.9 MB)
Technical support for the design team
We supply the material and we apply it, so the specification and the workmanship sit with one party. Send a finishes schedule, an elevation or a mood board and we will come back with the system, the build-up, the sample programme and a completed clause.