1、BSI Standards PublicationBS 1251:2015Open-fireplace componentsPublishing and copyright informationThe BSI copyright notice displayed in this document indicates when the documentwas last issued. The British Standards Institution 2015Published by BSI Standards Limited 2015ISBN 978 0 580 57839 7ICS 97.
2、100.30The following BSI references relate to the work on this document:Committee reference RHE/28Draft for comment 13/30157623 DCPublication historyFirst published November 1945Second edition October 1959Third edition November 1970Fourth edition October 1987Fifth (present) edition March 2015Amendmen
3、ts issued since publicationDate Text affectedBS 1251:2015 BRITISH STANDARDContentsForeword ii1 Scope 12 Normative references 13 Firebacks 14 Prefabricated fireplace surrounds and hearths 45 Throat forming lintels 126 Marking 14AnnexesAnnex A (normative) Heat resistance test 15Bibliography 16List of
4、figuresFigure1Typical assembly of open-fireplace components 2Figure 2 Firebacks 3Figure 3 Depth of recess and thickness of surround (Recessed surround viewedfrom back face) 5Figure 4 Frame fixing 6Figure 5 Throat hood/Otty hood 6Figure 6 Cut stone fire surround 8Figure 7 Heat plate 9Figure8Typical f
5、ixing brackets for cut stone surrounds 11Figure9Typical fixing locations for cut stone surrounds 11Figure 10 Precast concrete throat-forming lintel 13List of tablesTable 1 Fireback dimensions 4Table 2 Dimensions of fireplace openings 4Summary of pagesThis document comprises a front cover, an inside
6、front cover, pages i to ii,pages 1 to 16, an inside back cover and a back cover.BRITISH STANDARD BS 1251:2015 The British Standards Institution 2015 iForewordPublishing informationThis British Standard is published by BSI Standards Limited, under licence fromThe British Standards Institution, and ca
7、me into effect on 31 March 2015. It wasprepared by Technical Committee RHE/28, Domestic solid mineral fuelappliances. A list of organizations represented on this committee can beobtained on request to its secretary.SupersessionThis British Standard supersedes BS 1251:1987, which is withdrawn.Informa
8、tion about this documentThe principal changes introduced by this revision are as follows. Mention of different materials currently used in the construction offireplaces and their suitability. The minimum projection of the hearth of inset open fires has beendecreased in accordance with the Building R
9、egulations 1, 2 and 3. Requirements are specified for mechanical fixings for cut stone and boxedsection fireplace surrounds to secure them to chimney breasts.Presentational conventionsThe provisions of this standard are presented in roman (i.e. upright) type. Itsrequirements are expressed in sentenc
10、es in which the principal auxiliary verb is“shall”.Commentary, explanation and general informative material is presented insmaller italic type, and does not constitute a normative element.It should be noted that many desirable properties of open-fireplace componentscannot be specified objectively. H
11、owever, attention is drawn to the notes in thisstandard and to BS 8303, which gives guidelines for their assembly.Contractual and legal considerationsThis publication does not purport to include all the necessary provisions of acontract. Users are responsible for its correct application.Compliance w
12、ith a British Standard cannot confer immunity from legalobligations.BRITISH STANDARDBS 1251:2015ii The British Standards Institution 20151 ScopeThis British Standard specifies requirements for components which, whenassembled in accordance with BS 8303, form the setting for inset open fires ofnominal
13、 sizes 400 mm and 450 mm (see Figure 1).Clause 3 specifies requirements for firebacks for inset open fires without boilersor underfloor air supply used with solid fuel.Clause 4 specifies requirements for prefabricated fireplace surrounds and hearthsand excludes constructional hearths at floor level
14、(see Figure 1).Clause 5 specifies requirements for precast, reinforced concrete throat-forminglintels, excluding those designed to form part of a complete appliance.NOTE 1 Lintels conforming to this British Standard are suitable for use asload-bearing supports for brickwork.NOTE 2 Requirements for f
15、ireguards are specified in BS 8423.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in thisdocument and are indispensable for its application. For dated references, onlythe edition cited applies. For undated references, the latest edition of thereference
16、d document (including any amendments) applies.BS 4550-3, Methods of testing cement Part 3: Physical testsBS 4550-6, Methods of testing cement Part 6: Standard sand for mortar cubesBS 8303, Installation of domestic heating and cooking appliances burning solidmineral fuelsBS EN 197-1, Cement Part 1: C
17、omposition, specifications and conformity criteriafor common cementsBS EN 12390-3, Testing hardened concrete Part 3: Compressive strength of testspecimensBS EN 12620, Aggregates for concreteBS EN 14647, Calcium alumina cement Composition, specifications andconformity3 Firebacks3.1 DesignFirebacks sh
18、all be designed for installation in two, four or five pieces, as shownin Figure 2a).NOTE Two-piece firebacks may be manufactured in two separate sections, or in onesection with suitable horizontal scribing to enable the pieces to be readily separatedbefore installation.3.2 DimensionsThe dimensions o
19、f firebacks, when assembled without jointing, shall be as givenin Figure 2b) and Table 1.NOTE 1 Internal and vertical external angles may be sharp or rounded to a radiusnot exceeding 10 mm. External edges at the rear may be rounded to reduce the riskof damage to the edges.BRITISH STANDARD BS 1251:20
20、15 The British Standards Institution 2015 1Dimensions A and B shall be measured at the point where straight lines alongthe wings intersect straight lines along the front and back of the firebacks. Theminimum thickness of the firebacks at any point shall be 40 mm.NOTE 2 It is desirable for firebacks
21、to be made with a shallow groove in the frontface not less than 20 mm from the inner edge, to permit the insertion ofnon-combustible rope to ensure that the fireback forms an adequate seal to theback of the fireplace surround.Figure 1 Typical assembly of open-fireplace componentsKey1 Corrugated card
22、board 7 Insulating backfill2 Fireback 8 Mantel shelf3 Insulating backfill 9 Fireplace surround lintel4 Flaunching in heat-refractory mortar 10 Fireplace surround5 Factory-made gather 11 Fireplace surround jamb6 Flue linerNOTE Insulating backfill should be either:a) 1 part ordinary Portland cement to
23、 20 parts suitable lightweight expanded clay aggregate, minimally wetted;orb) 1 part ordinary Portland cement to 6 parts Vermiculite; orc) 1 part ordinary Portland cement to 10 parts Perlite.BRITISH STANDARDBS 1251:20152 The British Standards Institution 2015Figure 2 FirebacksTwo-piece Four-piece Fi
24、ve-piecea) Types of sectional firebacksb) Fireback dimensions (see Table 1)BRITISH STANDARD BS 1251:2015 The British Standards Institution 2015 3Table 1 Fireback dimensionsNominalsize of fireDimensionAA)BA)CA)DEF GB)HB)JC)KD)LB)MB)mm mm mm mm mm mm mm mm mm mm mm mm mm0to3 0to3 0to3400 380 250 170 5
25、60 470 100 340 43 150450 430 300 170 560 470 100 340 43 150ABCTolerances on dimensions:A)+15/0B)+10/0C)10D)0/-103.3 Heat resistanceWhen tested in accordance with A.2, a specimen of the fireback obtained inaccordance with A.1 shall show no signs of increased blistering, cracking,powdering or fusing.3
26、.4 InstallationWhere a fireback is intended to be supplied in one piece, it shall be possible tosplit this along the score line before installation.4 Prefabricated fireplace surrounds and hearths4.1 Dimensions4.1.1 Fire openings in fireplace surroundsThe dimensions of openings in fireplace surrounds
27、 shall be as given in Table 2.Table 2 Dimensions of fireplace openingsNominal size of fire DimensionWidth Heightmm mm mm400 410 560450 460 560Tolerances on dimensions: width: +10/0 mm height: 0/-5 mm4.1.2 Surrounds4.1.2.1 Flush back surroundsThe back of the surround at its periphery and around the f
28、ire opening shall bein the same plane. The thickness of the fireplace surround for a distance of atleast 50 mm from the fire opening shall be not greater than 55 mm, includingany integral metal fire frame. 25 mm glass fibre rope shall be attached to theslabbing with rope clips around the fire openin
29、g.BRITISH STANDARDBS 1251:20154 The British Standards Institution 20154.1.2.2 Recessed back surroundsWhere a fireplace is to be constructed for use with a shallow chimney breast(less than 350 mm deep) then a standard fireback or other inset appliance canproject proud of the chimney breast. In these
30、instances a recesses back surroundcan be used.The recess in the back of the surround shall be not more than 50 mm deep andshall be consistent up to a point 50 mm from the perimeter of the surround. Thethickness of the return at the perimeter shall be no thicker than the thickness ofthe face of the s
31、urround (see Figure 3).The thickness of the surround for a distance of at least 50 mm from the fireopening shall be not greater than 55 mm, including any integral metal fireframe. 25 mm glass fibre rope shall be attached to the slabbing with rope clipsaround the fire opening (see Figure 3).Figure 3
32、Depth of recess and thickness of surround (Recessed surround viewed fromback face)KeyR Depth of recessT1Perimeter returnT2Surround face thicknessMetal fire frames shall be attached using wire ties cast into the surround(see Figure 4).Where a surround is intended to be installed with an open fire, a
33、standardthroat forming lintel shall not be used. Instead, an otty hood or throat hoodshall be used.BRITISH STANDARD BS 1251:2015 The British Standards Institution 2015 5An otty hood or throat hood shall project forward of the chimney breast andhave a recessed groove for the fitting of a rope seal be
34、tween it and the recessedrear of the fire surround, to ensure there is no gap in the throat formation forthe open fire (see Figure 5).Figure 5 Throat hood/Otty hoodDimensions in millimetresKey1 Chimney breast less than 350 mm deep2 Throat hood/Otty hood3 Fireback brought forwardFigure 4 Frame fixing
35、KeyA Wire tied into slabbingBRITISH STANDARDBS 1251:20156 The British Standards Institution 20154.1.2.3 HearthsThe hearth shall extend not less than 225 mm beyond each side of the fireopening of the fireplace surround. The hearth shall project at least the minimumdimension specified for the grate or
36、 firebed being used, and this dimension shallbe not less than 300 mm in front of the face of the fireplace surround at thefire opening. The hearth shall also project at least 300 mm in front of theappliance firebed.Hearth thicknesses shall be dependent upon the fuel or appliance to be used,with a mi
37、nimum thickness of 20 mm. The hearth shall not extend under anyopen fire as a separate cast in situ or prefabricated back hearth will be requiredto match the level of the hearth supplied.4.1.2.4 Wooden mantelsWhere a fireplace consists of a marble, stone or ceramic back panel and hearthtogether with
38、 a wooden mantel, there shall be a minimum clearance tocombustible material of 300 mm above the fire opening and 150 mm either sideof the fire opening to the start of the wooden mantel.NOTE Extra clearance might be needed when the fireplace is constructed forcertain types of appliance.4.2 Constructi
39、on of fireplaces4.2.1 General4.2.1.1 Slabbed fireplace surroundsFor slabbed fireplace surrounds constructed from marble, stone, conglomerateand ceramic tiles on a backing of heat insulating cement mix, the backing ofsurrounds and hearths shall be constructed of a reinforced lightweight concretemix h
40、aving a thickness of not less than 30 mm for marble or stone and 40 mmfor tiles. The overall thickness, including any facing material, shall be not lessthan 48 mm. The backing of the marble or tiles shall be coated with a bondingagent before filling to aid adhesion and seal the material against stai
41、ning fromthe process.NOTE 1 See 4.2.3 for the fixings for fireplace surrounds.After manufacture, slabbed parts shall be left to dry overnight and covered witha membrane to allow the slabbing to cure evenly and not dry out too quickly.During this process the surround shall be protected from frost.NOT
42、E 2 High alumina cement has a drying time of approximately six hours andachieves complete setting within 24 hours.Normal Portland cement shall be left for 24 hours before moving.4.2.1.2 Cut stone fireplacesNOTE 1 Many fire surrounds are produced with an outer surround manufacturedfrom cut heavy ston
43、e sections, the most common design consisting of two verticallegs over which rests a horizontal lintel that has a mantel shelf on top (see Figure 6).Because cut stone surrounds have little inherent stability and are often unstableby design, with a large overhanging mantel shelf in comparison to the
44、width ofthe vertical legs, they shall be manufactured with provision for mechanical fixingof each stone either directly to the backing wall or to another stone which itselfis mechanically fixed to the backing wall.NOTE 2 See 4.2.3 for the fixings for fireplace surrounds.BRITISH STANDARD BS 1251:2015
45、 The British Standards Institution 2015 7Figure 6 Cut stone fire surroundKey1 Mantel shelf2 Lintel3 Leg4.2.1.3 Boxed section fireplace surroundsA boxed section fireplace surround shall be manufactured from natural stone ormarble and be marked as to its suitability with either a gas or solid fuel fir
46、e. Afireplace for solid fuel use shall either:a) have loose slips for the back panel with a minimum thickness of 30 mm ifdesigned to be used with an open convector type fire, or 50 mm if intendedto be used with a metal fire trim and refractory fireback; orb) be supplied with a slabbed and sectioned
47、back panel.The hearth shall be 50 mm solid and sectioned with a replaceable heat plate ofthe same material, marble, granite or metal to correspond with the fireopening, or boxed, sectioned and slabbed with a heat plate.BRITISH STANDARDBS 1251:20158 The British Standards Institution 2015NOTE 1 Facing
48、 materials: If marble or limestone is used for a fireplace for a solidfuel appliance they should be natural and not conglomerate (which constitutes a firerisk when used with such appliances). The back panel and hearth should be split, toaid expansion. Back panels should be split into three or four s
49、ections before slabbingback panels together, which should comprise legs and a one or two piece head(see Figure 7). Hearths should be split into two or three sections with a marble,limestone, granite or metal heat plate with a fireclay or similar strip directly in frontof the fire opening (see Figure 7). If ceramic tiles are used, it is recommended thatthey have a thickness of not less than 8 mm if their water absorption is greaterthan 3%. Ceramic tiles having a water absorption of less than 3% should have athickness
