Bsi bs en 13914 2 2016 (2017)

BS EN 13914-2:2016 Incorporating corrigendum March 2017 BS EN 13914-2:2016 BSI Standards Publication Design, preparation and application of external rendering and internal plastering Part 2: Internal plastering BS EN 13914-2:2016 BRITISH STANDARD National foreword This British Standard is the UK implementation of EN 13914-2:2016 It supersedes BS EN 13914-2:2005 which is withdrawn The UK participation in its preparation was entrusted to Technical Committee B/519, Masonry and associated testing A list of organizations represented on this committee can be obtained on request to its secretary National Annex NA provides additional information and guidance from the UK committee This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application © The British Standards Institution 2017 Published by BSI Standards Limited 2017 ISBN 978 580 98043 ICS 91.100.10 Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2016 Amendments/corrigenda issued since publication Date Text affected 31 March 2017 National Annex NA added BS EN 13914-2:2016 EN 13914-2 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM March 2016 ICS 91.100.10 Supersedes EN 13914-2:2005 English Version Design, preparation and application of external rendering and internal plastering - Part 2: Internal plastering Conception, préparation et mise en oeuvre des enduits extérieurs et intérieurs - Partie 2: Enduits intérieurs This European Standard was approved by CEN on January 2016 Planung, Zubereitung und Ausführung von Außen- und Innenputzen - Teil 2: Innenputze CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC 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 translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels © 2016 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref No EN 13914-2:2016 E BS EN EN 13914-2:2016 13914-2:2016 BS EN 13914-2:2016 13914-2:2016(E) (E) EN Contents Page European foreword Scope Normative references Terms and definitions 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Materials and accessories General Factory-made and semi-finished factory-made plasters — properties Materials for site-made plasters 10 Water 10 Reinforcement, carriers and beads 11 Fixings 12 Substructures 12 5.1 5.2 Essential principles and building programme 12 Essential principles 12 Building programme 13 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 6.11 Design 13 General 13 Factors influencing the plastering system 13 Durability 17 Thermal insulation 18 Acoustic properties 19 Plasters with enhanced resistance to soluble salts 19 Plasters with enhanced protection from x-ray radiation 19 Plastering system for decorative finish 19 Thickness of plaster coats on walls and ceilings 19 Types and standards of plaster finish 21 Air tightness 23 7.1 7.2 7.3 7.4 Preparation and application of plasters 24 Storage 24 Cleanliness and protection of the works 24 Considerations by the designer for application matters 24 Considerations by the applicator 25 8.1 8.2 8.3 8.4 Maintenance and repair (other than restoration) 27 General 27 Inspection 27 Efflorescence 27 Repairs to cracks 27 Annex A (normative) Design considerations for work and acceptance of smooth plaster finishes under aspects of lighting 29 Annex B (informative) Methods of minimizing the occurrence of cracks 31 Annex C (informative) Fixing applied backgrounds 32 Annex D (informative) Restoration of plasters 35 Bibliography 37 BS EN EN 13914-2:2016 13914-2:2016 BS EN EN13914-2:2016 13914-2:2016 (E) (E) European foreword This document (EN 13914-2:2016) has been prepared by Technical Committee CEN/TC 125 “Masonry”, the secretariat of which is held by BSI This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 2016, and conflicting national standards shall be withdrawn at the latest by September 2016 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights This document supersedes EN 13914-2:2005 The initial draft of this document was prepared by the European section of International Union of Contractors of Plastering, Dry Lining, Stucco and Related Activities (UIEP) at the request of the CEN Technical Sector Board (Resolution No.BTS1/56/1991) It has been revised by CEN/TC 125/WG in conjunction with experts of CEN/TC 241 Relevant data are summarized in a series of tables This part of EN 13914 applies to the design of plaster made of mortars containing inorganic and organic binders and mineral aggregate 1) which is applied to internal vertical and soffit surfaces of structures As this standard is a code-like document as opposed to the more conventional European product standard, it is appropriate to mention that, as with product standards, the use of the verbal form 'shall' denotes a requirement for which verification of compliance has to be able to be demonstrated Recommendations are denoted by the verbal form 'should' and should be followed unless there is a justifiable reason for not doing so It is not the function of this standard to assign responsibility for the design and application of any work or actions mentioned herein to any specific party Such responsibility is a matter for other documentation associated with the work, e.g the contract It has been assumed in the drafting of this document that the application of its provisions is entrusted to appropriately qualified and experienced persons, for whose guidance it has been prepared The content of CEN Technical Reports containing guidance relating to the design, preparation and application of plaster and plastering systems for gypsum (CEN/TR 15124), cement and/or lime (CEN/TR 15125) and polymer plasters (CEN/TR 15123) has been included According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom 1) The aggregate can be omitted from mortars made from gypsum plaster or anhydrite binders BS EN EN 13914-2:2016 13914-2:2016 BS EN 13914-2:2016 13914-2:2016(E) (E) EN Scope This European Standard deals with the design considerations and essential principles for internal plastering systems and application of plastering systems The different parts of the EN 13914 series of standards specify requirements and recommendations for detailing, design and material considerations, the selection of mixes and the application of gypsum plasters, gypsum/lime plasters, lightweight plasters, lime/gypsum-, cement- and cement/lime-based plasters, lime-based plasters, clay plasters, silicate plasters, organic plasters, polymer-modified plasters, etc This standard does not deal with the following: — external finishes; — painting and/or preparation; — impregnations; — structural repair of concrete; — prefabricated fibre-reinforced plaster elements Owing to the many and varied materials and practices and different climatic conditions in Europe it is not possible for certain aspects of the standard to enter into sufficient detail to be fully usable to practitioners in each country Such guidance to complement, but not alter, any basic European recommendations is given in documentation prepared by each country Aspects of this European Standard, the basic recommendations of which may need to be complemented, are indicated where they occur by a footnote referencing this clause Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies EN 197-1, Cement — Part 1: Composition, specifications and conformity criteria for common cements EN 413-1, Masonry cement — Part 1: Composition, specifications and conformity criteria EN 459-1, Building lime — Part 1: Definitions, specifications and conformity criteria EN 998-1:2010, Specification for mortar for masonry — Part 1: Rendering and plastering mortar EN 1008, Mixing water for concrete — Specification for sampling, testing and assessing the suitability of water, including water recovered from processes in the concrete industry, as mixing water for concrete EN 10088-1, Stainless steels — Part 1: List of stainless steels EN 10244-1, Steel wire and wire products — Non-ferrous metallic coatings on steel wire — Part 1: General principles EN 10244-2, Steel wire and wire products — Non-ferrous metallic coatings on steel wire — Part 2: Zinc or zinc alloy coatings BS EN EN 13914-2:2016 13914-2:2016 BS EN EN13914-2:2016 13914-2:2016 (E) (E) EN 10346, Continuously hot-dip coated steel flat products for cold forming — Technical delivery conditions EN 12878, Pigments for the colouring of building materials based on cement and/or lime — Specifications and methods of test EN 13055-1, Lightweight aggregates — Part 1: Lightweight aggregates for concrete, mortar and grout EN 13139, Aggregates for mortar EN 13279-1, Gypsum binders and gypsum plasters — Part 1: Definitions and requirements EN 13658-1, Metal lath and beads — Definitions, requirements and test methods — Part 1: Internal plastering EN 13914-1:2016, Design, preparation and application of external rendering and internal plastering — Part 1: External rendering EN 15824, Specifications for external renders and internal plasters based on organic binders EN ISO 16120-2, Non-alloy steel wire rod for conversion to wire — Part 2: Specific requirements for general-purpose wire rod (ISO 16120-2) Terms and definitions For the purposes of this document, the terms and definitions given in EN 998-1, EN 13279-1, EN 13914-1, EN 13658-1, EN 15824 and the following apply 3.1 plaster (noun) mixture of different materials (binders, additives, admixtures, water, aggregates) to obtain a surface finish which is applied internally to walls and ceilings 3.2 plastering (verb) application of plaster 3.3 gypsum plaster all kinds of gypsum building plaster, gypsum based building plaster and gypsum-lime building plaster used in buildings [SOURCE: EN 13279-1:2008, 3.2] 3.4 mineral based plaster plaster with one or more inorganic binders 3.5 organic plaster factory made plaster with one or more organic binders in paste or powder form BS EN EN 13914-2:2016 13914-2:2016 BS EN 13914-2:2016 13914-2:2016(E) (E) EN 3.6 designed plaster plaster whose composition and manufacturing method is chosen by the producer in order to achieve specified properties (performance concept) [SOURCE: EN 998-1:2010, 3.3.1, modified] 3.7 prescribed plaster plaster made in pre-determined proportions, the properties of which are assumed from the stated proportion of the constituents (recipe concept) [SOURCE: EN 998-1:2010, 3.3.2, modified] 3.8 plaster coat obtained by application of one or more layers with one or more mixes of the same product 3.9 plaster layer layer produced by the application of the same plaster in one or more operations, "fresh on fresh" 3.10 plaster system plaster coat or sequence of plaster coats to be applied to a background, including the possible use of a support and/or reinforcement and/or pre-treatment 3.11 site made plaster plaster batched and mixed on site 3.12 one coat plaster plaster applied in one coat which fulfils all the functions of a plastering system 3.13 thin coat mm to mm plaster coat applied to a surface 3.14 skim/filler coat 0,1 mm to mm plaster coat applied to a surface 3.15 reinforcement material incorporated within a plaster coat to improve resistance to cracking (e.g welded wire mesh, glass fibre mesh, fibres) [SOURCE: EN 13914-1:2016, 3.17, modified] 3.16 reinforcing coat polymer modified, mineral or organic plaster layer with a mesh embedded into it and applied over an undercoat or defective background which contributes to the minimising of cracks BS EN EN 13914-2:2016 13914-2:2016 BS EN EN13914-2:2016 13914-2:2016 (E) (E) [SOURCE: EN 13914-1:2016, 3.18, modified] 3.17 final coat last coat, decorative or not, of a plaster system [SOURCE: EN 13914-1:2016, 3.19, modified] 3.18 background surface of a construction element to which a plaster or a plaster system is to be applied [SOURCE: EN 13914-1:2016, 3.22, modified] 3.19 preparatory treatment actions to be taken on backgrounds with devices, machines and/or tools, to remove dust and unstable or deleterious material e.g efflorescence [SOURCE: EN 13914-1:2016, 3.23] 3.20 key property of a background or plaster coat which allows the bonding of a plaster without the need for a pre-treatment or carrier [SOURCE: EN 13914-1:2016, 3.24, modified] 3.21 pre-treatment application of a material on the background to improve the application properties of the plaster (e.g spatterdash, primer, bonding agent) [SOURCE: EN 13914-1:2016, 3.25, modified] 3.22 bond mechanical and/or chemical adhesion between the plaster and the background [SOURCE: EN 13914-1:2016, 3.26, modified] 3.23 bonding agent proprietary material used to provide or improve adhesion of the plaster or plaster system to the background where necessary [SOURCE: EN 13914-1:2016, 3.27, modified] 3.24 primer material for pre-treatment of the background Note to entry: background For example primers can be used to reduce suction or to stabilize the surface of the BS EN EN 13914-2:2016 13914-2:2016 BS EN 13914-2:2016 13914-2:2016(E) (E) EN [SOURCE: EN 13914-1:2016, 3.28] 3.25 spatterdash technique for pre-treatment characterized by brushing, throwing or spraying of site or factory made mortar onto a background to improve its bonding properties and/or to regulate the suction of the background [SOURCE: EN 13914-1:2016, 3.29] 3.26 dubbing out process of filling large localized irregularities in the background, such as hollows, prior to the application of a plaster coat [SOURCE: EN 13914-1:2016, 3.30, modified] 3.27 carrier product attached to the background to which a plaster is applied so that the plaster system is largely independent of the background (e.g lathing) [SOURCE: EN 13914-1:2016, 3.31, modified] 3.28 crazing network of short, irregular and very fine cracks up to approximately 0,2 mm in width Note to entry: Hairline cracks not impair the function of the plaster and are therefore acceptable to a limited extent [SOURCE: EN 13914-1:2016, 3.33, modified] 3.29 depth gauge band of plaster or bead used in setting out for a required thickness or evenness [SOURCE: EN 13914-1:2016, 3.34, modified] 3.30 drying time necessary hardening- and drying- time until the next layer or coating can be applied [SOURCE: EN 13914-1:2016, 3.35] 3.31 lining temporary frame for plastering up to 3.32 efflorescence formation of salts on a surface during drying caused by the presence of soluble substances [SOURCE: EN 13914-1:2016, 3.34] BS EN EN 13914-2:2016 13914-2:2016 BS EN 13914-2:2016 13914-2:2016(E) (E) EN 7.4.2 Pre-treatment for gypsum plaster The following can be used for gypsum plaster: a) organic bonding agents for sufficient adhesion; b) primers for uniform suction behaviour 7.4.3 Pre-treatment for lime/cement and clay plaster The following can be used: a) mineral bonding agents for sufficient adhesion; b) primers for uniform suction behaviour; c) spatterdash etc 7.4.4 Pre-treatment for organic plaster For organic plaster, primers can be used to ensure sufficient adhesion 7.4.5 Pre-treatment of mixed backgrounds Suitable measures shall be taken where plastering is to be continued across backgrounds of different materials, e.g concrete abutting masonry The type of measure, e.g joints or support, will depend on the individual situation 7.4.6 Dubbing-out Special treatment may be required if the background is uneven, with localized hollows The method of working will depend upon the depth and area of the hollow, the type of background and the plaster to be used 7.4.7 One-coat system A one-coat system may be applied in one layer or in two passes by wet on wet It can provide different plaster surface finishes, e.g smooth finishes, felted finishes or other types of finish, depending on the composition of the plaster and the tool to be used 7.4.8 Multi-coat system 7.4.8.1 General The recommendations of 7.4.7 apply to the first coat of a multi-coat system The surface of a preceding coat should be prepared to present a suitable key, if necessary, to assist bonding with a subsequent coat 7.4.8.2 Undercoat For either two or more coat systems, application of the initial undercoat can be carried out in two continuous operations and may be applied in multiple passes by wet on wet (see also 6.2.4) For multi-coat plaster systems it is generally unnecessary to ensure that thorough drying of one coat has taken place before the application of the following coat, but sufficient strength should have developed However, certain types of plasters, e.g polymer plasters, have to be applied to a dry background/undercoat 26 BS EN EN 13914-2:2016 13914-2:2016 BS EN EN13914-2:2016 13914-2:2016 (E) (E) 7.4.8.3 Final coat A multi-coat system can be finished in the same way as a one-coat system of an equivalent thickness Where it is necessary to plaster over an existing substrate, it should have sufficient bond strength to support and provide adhesion for the new plaster Where an organic plaster coat is applied to cement or cement lime background, the entire substrate has to be hardened, clean and dry to avoid de-bonding of the plaster coat Undercoat plasters shall have a compressive strength ≥ N/mm2 to be suitable for the application of organic plasters Maintenance and repair (other than restoration) 8.1 General This clause gives recommendations for the maintenance and repair of plaster where, for instance, the plaster or the building structures are made of materials and techniques that are similar to those used in current construction The principles and recommendations given in the previous clauses of this document generally apply except where advised otherwise in this clause 8.2 Inspection The nature and extent of the defects should be ascertained by someone knowledgeable and experienced in the subject It is important to ascertain the basic cause of the defects, especially where they are due to inappropriate design or deficiencies in the background 8.3 Efflorescence This is caused by the presence of soluble salts such as sulfates, nitrates and chlorides in the background and the presence of sufficient water to carry these to the surface as the structure dries To overcome this problem, all sources of moisture should be removed The contaminated plaster should be removed over an area of approximately m surrounding the affected areas Any salts on the background surface shall be removed by the dry method and the joints raked When this has been done a renovation plaster may be applied or other measures taken, e.g provision of a new background 8.4 Repairs to cracks 8.4.1 General The method will depend upon the width, depth and the cause of the crack Repairs to partial areas may remain visible One solution is to provide a coating incorporating reinforcement mesh on the surface 8.4.2 Repairs to fine cracks and crazing in plasterwork only Such cracks may be treated with a purpose-made plaster and redecorated 8.4.3 Repairs to wider cracks in plasterwork only Such cracks, if not accompanied by loss of adhesion, can normally be repaired by forming a V-cut to slightly widen them and filling the gap with an appropriate product If accompanied by lack of bond, loose materials should be removed and replaced with new plaster 27 BS EN EN 13914-2:2016 13914-2:2016 BS EN 13914-2:2016 13914-2:2016(E) (E) EN 8.4.4 Repairs to cracks in plasterwork and background The cause of the crack should be identified and rectified prior to making the repair If the background cannot be effectively repaired, special measures will be required in each case The method of repair will depend on each individual case 28 BS EN EN 13914-2:2016 13914-2:2016 BS EN EN13914-2:2016 13914-2:2016 (E) (E) Annex A (normative) Design considerations for work and acceptance of smooth plaster finishes under aspects of lighting A.1 General This annex gives general advice Any detailed national regulations regarding lighting considerations will take precedence A.2 Lighting — general recommendations As the general level of lighting can have a critical effect on the appearance of a finished plaster surface, a higher level of lighting is often needed for such work The temporary lighting conditions on site for the plasterer should simulate the same or higher lighting conditions produced by the final permanent installation NOTE This can readily be obtained by the simulation of the future lighting situation in addition to the local light sources providing the general working light However, the appearance of a surface can also be affected by the angle of illumination which can accentuate minor deviations from line Hence the direction of the supplementary lighting should be adjustable Examples of such onerous lighting conditions are: — natural light from a window or another opening; — artificial light from close wall fittings, cornice lighting, etc The appropriate classes of flatness and smoothness should be given in the project specification However, irregularities due to the lighting conditions can still be visible even when classes of evenness and smoothness are specified and the work has been carried out accordingly A.3 Lighting generally falling perpendicular to the plaster surface For the reasons given in A.2, normal working and acceptance conditions in many countries are limited to when lighting and viewing are from positions normal to the surface A.4 Glancing light conditions Issues with the visual appearance can arise where the final permanent lighting of any surface is to fall at glancing angles In such situations plastering under glancing light would constitute working under special conditions When working under such conditions: — the direction of supplementary lighting shall be adjustable, and — the designer shall inform the plasterer, before the start of plastering, of the type and location of the final permanent lighting 29 BS EN EN 13914-2:2016 13914-2:2016 BS EN 13914-2:2016 13914-2:2016(E) (E) EN This lighting, whether permanent or temporary, shall be installed prior to plastering Certain lighting conditions may appear to show surface unevenness even though the finish is as flat as required by the specification A.5 Viewing conditions When inspecting plasterwork for acceptance, surfaces shall be viewed from the positions normally used in the adjacent area NOTE In general, this would be from the entrance doorway and from the centre of the room in a normal domestic house and from about m away from the surface in larger areas 30 BS EN EN 13914-2:2016 13914-2:2016 BS EN EN13914-2:2016 13914-2:2016 (E) (E) Annex B (informative) Methods of minimizing the occurrence of cracks B.1 General To minimize background movement and subsequent cracking of the plaster, the design should take into account — whether the background materials are dry at the time of plastering; — the allowance of sufficient time between the construction of the background and the application of the plaster An approximate assessment of background moisture may be made by the generally accepted test methods of visual examination, wetting and/or wiping B.2 Movement/Joints Where a movement joint occurs in the background, the movement joint should be provided (by the designer) in the plastering at a location coincident with that of joint in the background The resulting gap should be sealed with a suitable joint sealant Movement joints can also be formed using a movement bead Plastered metal lathing is subject to movement due to temperature To limit the tendency to crack, large uninterrupted areas of plastering on lathing should be divided at intervals in accordance with manufacturer's instructions B.3 Dissimilar backgrounds which cause differential movement Where plastering is to be continued across dissimilar backgrounds the possibility of differential movement at their junction should be considered At such points, movement joints in the background and the plaster should be provided If differential movement is a remote possibility and it is not deemed necessary or appropriate to provide a joint in the plastering, other precautions should be taken to minimize the effect of any movement in the background on the plastering 31 BS EN EN 13914-2:2016 13914-2:2016 BS EN 13914-2:2016 13914-2:2016(E) (E) EN Annex C (informative) Fixing applied backgrounds C.1 Fixing applied backgrounds in welded wire meshes or metal lath C.1.1 Fixings The fixings for metal lath should be of corrosion-resistant materials compatible with the material of the lath Fixings should be of adequate size for the weight to be supported and the type of firring or structure on which the metal lath will be fixed The fixing heads should be of sufficient size to prevent pull-through The fixings and overlaps should meet the fire resistance criteria of the application for which they will be used (reference to be made to the manufacturer's installation specifications) C.1.2 Fixing for all types of welded wire mesh or lath The type of support and the fixing centres should be chosen taking into consideration the type and grade of the welded wire mesh and lathing and the weight to be supported so that the welded wire mesh and lathing are held rigidly The laths and the welded wire meshes should be fixed with the stiffening ribs or wires running at right angles to the support For mixed backgrounds of masonry and timber or masonry and steel, welded wire meshes or laths should be fixed to the masonry wherever possible The lath or welded wire mesh should be fixed to any other background (concrete or masonry) using appropriate fixings such as plugs, screws, but with regard to any requirements for fire and corrosion resistance The maximum span between supports will depend on the type of lath or welded wire mesh used, but shall not exceed 700 mm for walls and 450 mm for ceilings Manufacturer's recommendations should also be considered with regard to the type of lath being used The lath or welded wire mesh should always be fixed in a staggered pattern The number of fixings to the support depends on the type of lath or welded wire mesh, but the maximum distance between the fixing and the support should be 150 mm The laths or welded wire meshes should be lapped on all sides by not less than 100 mm in the horizontal and vertical direction The ribs, where present, should be nested and fixed together Where end laps occur between supports, the lath or welded wire mesh should be lapped by not less than 100 mm and the laths should be rigidly tied together on all sides C.2 Metallic mesh for reinforcement C.2.1 Fixings Metallic mesh fixings should be of corrosion-resistant materials compatible with the material of the mesh Fixings should be of adequate size for the weight to be supported The fixings should allow a maximum distance between the metallic reinforcement and the background 32 BS EN EN 13914-2:2016 13914-2:2016 BS EN EN13914-2:2016 13914-2:2016 (E) (E) C.2.2 Fixing of metallic mesh The metallic mesh type to be used as reinforcement should be fixed to the background with the appropriate fixings The number of fixings depends on the type of mesh The metallic mesh shall be compatible with the plaster being applied Metallic mesh shall be embedded in the outer half of the overall thickness of the plaster It should be lapped in all directions with an overlap of not less than 100 mm C.3 Non-metallic mesh for reinforcement The non-metallic mesh shall be compatible with the plaster being applied The mesh should be lapped by at least 200 mm over adjacent backgrounds and 100 mm between adjacent sheets The same applies to mesh applied to insulation a) Undercoat: The mesh should be embedded in the upper half of one-coat plasters b) Reinforcing coat: A reinforcing plaster with a wire mesh should be applied (approximately mm to mm) to the hardened undercoat The final coat should be applied after sufficient drying time C.4 Beads and temporary formwork Beads should be fixed in line before plastering Formwork is temporarily fixed to openings and frames instead of beads in order to facilitate, for example, the use of clip-on frames (see Figure C.1) The use of stop beads is recommended when using prefabricated metal door frames without reveals or returns (see Figure C.2) Key plaster temporary formwork wall Figure C.1 — Examples of applications of beads and temporary formwork around openings Temporary formwork at opening prior to fitting clip-on frames 33 BS EN EN 13914-2:2016 13914-2:2016 BS EN 13914-2:2016 13914-2:2016(E) (E) EN Dimensions in millimetres Key plaster prefabricated metal door set in position wall architrave bead Figure C.2 — Examples of applications of beads and temporary formwork around openings - Use of prefabricated metal doorsets 34 BS EN EN 13914-2:2016 13914-2:2016 BS EN EN13914-2:2016 13914-2:2016 (E) (E) Annex D (informative) Restoration of plasters D.1 General This section gives recommendations for the renovation and repair of defective plasters where the types of material and technique used are often different from those in current usage As the range of backgrounds, types of plaster and their constituent materials have varied greatly throughout Europe over the centuries the recommendations given here are mostly of a general nature The advice of experts practising in the type of work involved should always be sought Designers, applicators and others involved should work in close co-operation and with any authority, if involved Before undertaking such work, the causes of deterioration should be established and the existing materials identified so that materials with similar properties can be used in the repair Depending upon the condition of the background as revealed by the investigation, it may be necessary to stabilize or damp-proof it prior to plastering Such treatment may take a considerable time to dry out before plastering can start D.2 Design The restoration work should be designed taking into account the likely conditions of exposure (see 6.3.2) When choosing a plastering system for restoration work, account should be taken of chemical, physical and mechanical interactions that can occur between coats and with the background A choice should be made as to whether the materials to be specified for the repair are — of similar composition to those originally used, or — compatible with the materials originally used A further choice should be made as to whether to reproduce the original design details, which may not be technically appropriate, or to incorporate improved details Consideration should be given to the use of trial panels for the approval of design and suitability including texture, colour, etc of the renovation works D.3 Application D.3.1 General The condition of the background and plaster coats is often only fully revealed when access is provided to enable close inspections and defective material is either removed or specially treated This may necessitate the reconsideration of certain aspects of the work e.g its extent Any proprietary products used should be applied taking the manufacturer's recommendations into account 35 BS EN EN 13914-2:2016 13914-2:2016 BS EN 13914-2:2016 13914-2:2016(E) (E) EN D.3.2 Hollow or loose parts of the background Loose materials should be removed or stabilized Specialist advice should be sought if further treatment is necessary D.3.3 Patching and remodelling The properties of patching plaster should be as similar as possible to the existing plaster 36 BS EN EN 13914-2:2016 13914-2:2016 BS EN EN13914-2:2016 13914-2:2016 (E) (E) Bibliography EN 934-3, Admixtures for concrete, mortar and grout — Part 3: Admixtures for masonry mortar — Definitions, requirements, conformity and marking and labelling EN 1996-2:2006, Eurocode 6: Design of masonry structures — Part 2: Design considerations, selection of materials and execution of masonry EN 13496, Thermal insulation products for building applications — Determination of the mechanical properties of glass fibre meshes as reinforcement for External Thermal Insulation Composite Systems with renders (ETICS) EN 16566, Paints and varnishes — Fillers for internal and/or external works — Adaptation of fillers to European standards 37 BS EN 13914-2:2016 National Annex NA (informative) Internal plastering: guidance on the use of BS EN 13914-2 NA.1 Who provides and fixes beads, templates, etc and to what line? It should be noted that this standard states in subclause 6.9.6 that beads, depth beads and plastering templates (e.g for openings) ‘shall be described in detail in the specification’ It would be advisable for contract documentation to state whose responsibility it is to provide and to fix the temporary frames and/or templates NA.2 Quality levels of smooth finishes and flatness Quality levels of smooth finishes (subclause 6.10.2) and flatness (subclause 6.10.3) are categorized differently and are described separately Four levels of smooth finish are categorized in Table and five classes of flatness are categorized in Table It should be noted that the standard of flatness that can be achieved with the final plaster surface (column of Table 6) is dependent upon the minimum standard of flatness of the background provided (column of Table 6) The UK committee is of the opinion that the contract documentation should state which level of smooth finish and class of flatness is required In doing so, it should be borne in mind what standard of flatness the background is required to achieve (see column of Table 6) to facilitate the class of flatness required of the final plaster surface It might be considered appropriate to make the standard of flatness of the background required by Table a term of the contract documentation NA.3 Minimum plaster thickness for various classes of flatness Although not stated in the standard, it is likely that in order to achieve the flatness required by classes 1, and in Table 6, the plaster should have a minimum thickness of at least 10 mm Footnote a at the bottom of Table states that classes and are only appropriate for plaster thicknesses of mm or less Furthermore, if the minimum standard of the background flatness does not reach the standard required in Table 6, column 3, to compensate for this deficiency the UK committee recommends the application of a greater thickness of plaster than 10 mm in order to achieve the overall required 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