EN 1015-21:2002

Methods of test for mortar for masonry - Part 21: Determination of the compatibility of one-coat rendering mortars with substrates

This European Standard specifies a test method for the evaluation of the compatibility with given backgrounds of One-Coat (OC) rendering mortars. The evaluation is based on the determination of the adhesion strength and water permeability of the hardened render applied on tested substrates, after exposure to weathering cycles.

Prüfverfahren für Mörtel für Mauerwerk - Teil 21: Bestimmung der Verträglichkeit von Einlagenputzmörteln mit Untergründen

Diese Europäische Norm legt die Verfahren zur Bewertung der Verträglichkeit von Einlagenputzmörteln (OC) mit den in Frage kommenden Untergründen fest. Die Bewertung basiert auf der Bestimmung der Haftfestigkeit und der Wasserdurchlässigkeit des erhärteten Putzes, der auf geprüften Untergründen aufgetragen und bewittert wurde.

Méthodes d'essai des mortiers pour maçonnerie - Partie 21: Détermination de la compatibilité des mortiers d'enduit extérieur mono-couche avec les supports

La présente Norme européenne décrit une méthode de détermination de la compatibilité des mortiers d'enduit mono-couche (MC) avec les supports sur lesquels ils doivent être appliqués.
Cette détermination est basée sur la mesure de l'adhérence et de la perméabilité à l'eau de l'enduit durci appliqué sur des supports définis, après cycles de conditionnement.

Metode preskušanja zidarske malte – 21. del: Določevanje združljivosti enoslojnih ometov s podlagami

General Information

• Status: Published
• Publication Date: 03-Dec-2002
• ICS: 91.100.10 - Cement. Gypsum. Lime. Mortar
• Technical Committee: CEN/TC 125 - Masonry
• Drafting Committee: CEN/TC 125/WG 4 - Test methods
• Current Stage: 9093 - Decision to confirm - Review Enquiry
• Start Date: 23-Jan-2025
• Completion Date: 14-Apr-2025
• Directive: 305/2011 - Regulation (eu) No 305/2011 of the European Parliament and of the Council of 9 march 2011 laying down harmonised conditions for the marketing of construction products and repealing council directive 89/106/eec
• Directive: 89/106/EEC - Construction products
• Ref Project: SIST EN 1015-21:2004 - Methods of test for mortar for masonry - Part 21: Determination of the compatibility of one-coat rendering mortars with substrates

Overview

EN 1015-21:2002 is a CEN test standard that specifies a laboratory method to determine the compatibility of One‑Coat (OC) rendering mortars with substrates. Compatibility is assessed by measuring the adhesion strength and water permeability of hardened renders applied to representative substrates after exposure to prescribed weathering/conditioning cycles. The procedure helps manufacturers, specifiers and test laboratories verify that a one‑coat render will perform as intended on given backgrounds.

Key topics and technical requirements

• Scope: Evaluation of OC rendering mortars on defined substrates (strong and weak) using adhesion and permeability tests after conditioning.
• Substrates: Minimum two panel types representing worst‑case field conditions, typically:
  • Strong substrate: concrete panel (300 × 300 × 40 mm minimum)
  • Weak substrate: lightweight masonry unit (e.g. autoclaved aerated concrete)
• Render application: Two thicknesses per panel - 10 mm ±1 mm and 20 mm ±1 mm; applied on vertical substrates per manufacturer instructions.
• Curing and conditioning:
  • Cure for at least 28 days at 20 °C ±2 °C and 65 % ±5 % RH.
  • Two series of four cycles each: heating/freezing (infra‑red surface heating to 60 °C ±2 °C; freeze at –15 °C ±1 °C) and humidification/freezing (partial immersion, then freeze). Record damage after each cycle.
• Water permeability test:
  • Apparatus uses a 200 mm diameter cone and a sustained 100 mm head of water.
  • Measure water flow needed to keep level constant over 48 hours; express as ml/(cm²·48 h).
• Adhesion test:
  • Performed after permeability test and conditioning, using the pull‑off method described in EN 1015‑12; report adhesive strength to 0.1 N/mm² and mode of failure.
• Reporting: Detailed test report including mortar designation, mixing ratio, flow, substrate description (including capillary absorption), specimen dimensions, individual permeability and adhesion values, and observed failure modes.

Applications and users

• Who uses it: mortar manufacturers, independent test laboratories, specifiers (architects, façade engineers), building product certifiers and compliance assessors.
• Practical uses:
  • Validate compatibility of one‑coat renders with specific masonry or concrete substrates.
  • Support product datasheets, CE marking and technical declarations.
  • Inform substrate preparation and application guidance to minimize failures (delamination, excessive water ingress).

Related standards

• EN 1015‑12 (adhesive strength / pull‑off)
• EN 1015‑2, EN 1015‑3, EN 1015‑9 (sampling, consistency, workable life)
• EN 772‑11 (water absorption of masonry units)
• prEN 998‑1 (specification for rendering and plastering mortar)

Keywords: EN 1015-21, one‑coat rendering mortars, compatibility test, adhesion strength, water permeability, substrate compatibility, weathering cycles, CEN standard.

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Prüfverfahren für Mörtel für Mauerwerk - Teil 21: Bestimmung der Verträglichkeit von Einlagenputzmörteln mit UntergründenMéthodes d'essai des mortiers pour maçonnerie - Partie 21: Détermination de la compatibilité des mortiers d'enduit extérieur mono-couche avec les supportsMethods of test for mortar for masonry - Part 21: Determination of the compatibility of one-coat rendering mortars with substrates91.100.10Cement. Mavec. Apno. MaltaCement. Gypsum. Lime. MortarICS:Ta slovenski standard je istoveten z:EN 1015-21:2002SIST EN 1015-21:2004en01-januar-2004SIST EN 1015-21:2004SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 1015-21December 2002ICS 91.100.10English versionMethods of test for mortar for masonry - Part 21: Determinationof the compatibility of one-coat rendering mortars withsubstratesMéthodes d'essai des mortiers pour maçonneries - Partie21: Détermination de la compatibilité des mortiers d'enduitextérieur mono-couches avec leur armaturePrüfverfahren für Mörtel für Mauerwerk - Teil 21:Bestimmung der Verträglichkeit von Einlagenputzmörtelnmit UntergründenThis European Standard was approved by CEN on 6 July 2002.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2002 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 1015-21:2002 ESIST EN 1015-21:2004
...