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Sand Microtadelakt arches in the grand atrium of the Calligraphy Museum, Madinah
Specification and technical data

Lime plaster and tadelakt — specification and technical data

A one-component hydraulic lime plaster with marble dust, laid by trowel at 1 to 4 mm over a prepared base. It carries the hardness and the standards record of a mineral coating while reading as a hand-worked surface — tadelakt, marmarino or polished plaster, depending on how it is finished.

The system

What sits against what, from the substrate outwards. Junctions, movement joints and edge details are project-specific — send us the drawings and we will mark them up.

Microtadelakt on a prepared mineral base

Grain sizes are selected by coat: Base for build, Regular or Medium for the finish, Fine for the closest work.

BUILD ORDER — SUBSTRATE FIRST, IN SEQUENCE Substrate
Concrete, cementitious mortar, ceramic, MDF, plaster or plasterboard. Clean, free of grease, consolidated and true.
 Consolidation and barriers
Compactec mortar consolidator, fibreglass mesh, vapour barrier or Vapoepox rising damp barrier where the substrate calls for it.
 Primer
Primer 100 adhesion promoter on absorbent and non-absorbent substrates.
 Base coats
Two coats of Microtadelakt Base by metal trowel. 4 hours between coats, sanded at 40 grit.
 Finish coats
Microtadelakt Regular, Medium or Base, worked wet-on-wet or wet-on-dry to the sheen required.
 Sealer
Sealed 24 to 48 hours after hardening, at below 5% moisture: Hidroprimer with Aquamax, or Maxipur.

Performance data

Taken from the manufacturers' own technical data sheets, with the standard each figure was measured against. Product-level figures are on the product pages below.

Property Result Standard
Applied thickness 1 – 4 mm Cemher data sheet
Emissions into indoor air A+ UNI EN ISO 16000-6:2019 / UNE EN 16516:2018
Thermal conductivity 0.46 W/mK UNI EN 12664:2002
Reaction to fire Class A1 / A1FL UNE EN 13501-1:2019
Adhesion strength > 4 N/mm², Class B 4.0 UNI EN 13892-8:2003 / UNE EN 13813:2014
Impact resistance > 18.5 Nm, IR 18 UNI EN 6272-2:2012
Surface hardness > 200 N/mm², SH 200 UNI EN 13892-6:2003
Compressive strength > 40 N/mm², Class C40 UNI EN 13892-2:2005
Abrasion resistance (BCA) Class AR 0.5, max 50 µm UNI EN 13892-4:2003
Water penetration under pressure 5 bar, 3 days — no penetration UNE EN 14891:2017 / UNI EN 12390-8:2020
Slip resistance USRV 41, Class 2 UNE EN 12633:2003
Permeability to liquid water < 0.1 kg/(m²·h^0.5), Class II UNE EN ISO 1062-3:2008
Water vapour transmission Class 1, Sd < 5 m UNE EN ISO 7783-2:2012
Workability at 20 °C Approx. 120 minutes; pot life 3 hours Cemher data sheet
Minimum application temperature + 10 °C Cemher data sheet
Shelf life 24 months from manufacture, stored 10 – 30 °C, dry and ventilated Cemher data sheet

Products in this family

One page per technical data sheet. Each carries the manufacturer's declared figures, the limits, a specification clause and the full document set.

Cemher Cemher Microtadelakt One-component lime plaster A one-component hydraulic lime plaster with marble dust, trowelled at 1 to 4 mm over a prepared base. Worked wet-on-wet or wet-on-dry it produces tadelakt, marmarino or polished plaster effects from a single material, with a full EN standards record behind it. Cemher Cemher Microtadelakt Thick Base Lime-based plaster for high build The high-build member of the Microtadelakt system: a lime-based mortar with graded aggregates for 5 to 15 mm builds, used to bring an out-of-true substrate into tolerance before the finish coats go on, and for exterior work. Cemher Microtadelakt — four grain sizes Lime-based plaster, four grain sizes The four-grain system sheet, declared to UNE-EN 13813. Base builds and levels, Medium and Regular carry the finish, Fine closes the surface. Selecting the right grain per coat is what produces the sheen the drawings show.

Where not to use it

Specifying a material into the wrong place is the most expensive mistake on a finishes package. These are the limits we will raise at review whether or not they are asked about.

  • Values marked as tested without sealer. The sealed system performs differently and the sealer has its own data sheet.
  • Do not apply below 10 °C. Low temperatures extend, and high temperatures shorten, pot life and drying.
  • Suitable over hot water underfloor heating; not over electric underfloor heating.
  • pH 12 after one day. Rubber gloves and eye protection during application.
  • Tadelakt in wet areas is not fully impermeable and needs re-soaping every one to two months to keep its water repellency.
  • Not acid resistant. Citrus, wine, vinegar and household cleaners will damage the surface.
Specification clause

Lime plaster: Cemher Microtadelakt one-component lime plaster in colour [ref], applied 1–4 mm in [number] coats over two coats of Microtadelakt Base on the prepared substrate, finished [tadelakt / marmarino / polished plaster] to the approved sample panel. Primer 100 adhesion promoter to all substrates. Reaction to fire Class A1 to UNE EN 13501-1:2019. Sealed with [Aquamax / Maxipur] not less than 24 hours after hardening and below 5% substrate moisture. Supply and application by Conmarble Natural Finishes.

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.

Document library

Every publishable document for this family, reproduced in full and unaltered under our cover. Free to download, no form.

Featured projects

Built with this material, by our own artisans. Open the project for the full set of photographs and the story of the installation.

Sand Microtadelakt arches in the grand atrium of the Calligraphy Museum, Madinah
Calligraphy Museum, Madinah Microtadelakt lime plaster across the atrium and halls View the project →
Microtadelakt polished lime plaster on the curved display walls at Afraa Boutique, Lusail
Afraa Boutique, Place Vendôme Microtadelakt on the curved display walls View the project →

Related systems

Microcement A seamless mineral coating at 2 to 3 mm over a prepared substrate, sealed to a defined system. Microcement is durable and low-VOC. It is a cementitious product: specify it for wear, chemical exposure and continuity, not as a natural or breathable finish. Clay plaster An unfired clay plaster, pigmented through the body, applied by hand over a primed substrate. It is a finish, not a waterproofing layer: it breathes, buffers humidity and is repaired rather than replaced. Interior walls and ceilings only.

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.

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