Health and Safety ExecutiveHealth and Safety series booklet (HS(G)32) Safety in falsework for

in situ beams and slabs

ContentsExplanation of terms 3

Introduction 5

Statutory responsibilities 5

Categories of falsework 5

Preparation 7Control documents 7Detailing 7

Co-ordination 15

Site supervision 16

Materials on site 16

Timber materials 16

Steel or iron products 18

Miscellaneous materials 18

Proprietary items 18

Erection 18Foundations andThe frameworkChecking 19

Dismantling 19

Appendix A

setting out 1819

Suggested layout of control documents 21

Appendix BSuggested foundation details toconditions 23

Appendix CTypical solutions for falseworksconcrete beams 25

Appendix D

suit vaious ground

to support in situ

Typical solutions for falseworks to support in situconcrete slabs 32

Appendix EStatutory requirements and references 38

London: Her Majesty’s Stationery Office

@Crown copyright 1987First published 1987

HS(G) seriesThe purpose of this series is to provide guidance for thosewho have duties under the Health and Safety at Work etc Act1974 and other relevant legislation. It gives guidance on thepractical application of regulations made under the Act, but itshould not be regarded as an authoritative interpretation of thelaw. __

Further advice on this or any other HSE publications may beobtained from Area Offices of HSE or from the generalenquiry points listed below.

Health and Safety ExecutiveLibrary and Information ServicesBroad LaneSHEFFIELD S3 7HQTelephone: (0742) 752539 Telex: 54556

Health and Safety ExecutiveLibrary and Information ServicesSt Hugh’s HouseStanley PrecinctTrinity RoadBOOTLEMerseyside L20 3QYTelephone: 051-9514381 Telex: 628235

Health and Safety ExecutiveLibrary and Information ServicesBaynards House1 Chepstow PlaceWestboume GroveLONDON W2 4TFTelephone: 01-2210416 or 01-2210870 Telex 25683

ISBN O 118839004

Explanation of terms

Falsework

In BS 5975 falsework is defined as “anytemporary structure used to support a permanentstructure while it is not self supporting”.

This document only covers falsework forreinforced in-situ concrete beams not exceeding1.Om deep and slabs not heavier than solid300mm thick.

Category 1 falsework:

Falseworks which may be constructed fromsketches derived from typical solutions, fromproprietary manufacturers catalogues or, wherethe falsework is very simple, based on previousexperience of many similar successful schemes.

Category 2 falsework:

Falsework schemes with special factors (listed inTable 1) which may require a falsework designerto make technical judgments, to carry outcalculations and/or prepare drawings orsketches.

Falsework contractor:

The persons, company or organisationundertaking the erection of a falsework. This mayform either part or the whole of their work onthe site.

Main contractor:

The contractor in overall control of the site. Thismay or may not be the falsework contractor.

Falsework brief:

The document which sets out the generalrequirements, location and purpose of thefalsework.

Site inspection record:

The document which sets out the site conditionswhich could affect the choice of falsework andits erection, and confirms the information given inthe falsework brief.

Falsework scheme summary:

The document which summarises the moreimportant elements of the falsework scheme.

Falsework detailer:

The person appointed by the falseworkcontractor to prepare details of Category 1falsework (eg from typical solutions proprietarycatalogues or in the most simple cases based onexperience) for use on a particular site.

Falsework designer:

A person who is qualified to prepare aCategory 2 falsework scheme.

Falsework co-ordinator

The person nominated to co-ordinate the variousaspects of building the falsework, as specified inparas 55-59. The person may be appointed bythe main contractor but on smaller falseworkcontracts the person nominated could be thefalsework contractors site supervisor.

Introduction

1 The failure of any falsework may cause injuryor death to those working on or near to it, aswell as loss of time and money.

2 Many past failures occurred on fairly simplestructures erected by smaller falseworkcontractors. The causes were forseeable andcould have been prevented by properconsideration when planning, erecting, loading ordismantling the falsework. Procedures toencourage a full consideration of these aspectsare set out in this document,

3 This document deals only with falseworkwhich provides temporary support to formworkfor in-situ concrete beams and slabs. Suchtemporary supports should be strong enough tosafely supports all the various forces associatedwith the placing of in-situ concrete.

4 It is primaily for the smaller contractor (thefalsework sub-contractor or the generalcontractor who undertakes some falseworkconstruction) who does not employ design staff.However as the principles apply to mostfalsework schemes, it should be of value to allcontractors undertaking this type of work. As afurther aid, a leaflet containing a check list forthe erection and dismantling all types offalsework has been published to be a companionto this guidance.

5 Falsework should be constructed inaccordance with BS 5975 The Code of Practicefor Falsework. This guidance both complementsthe Code of Practice and helps those withoutdesign staff by concentrating on safety aspectsand by giving detailed advice on a limited rangeof falseworks. It is important for contractors to beaware of the limitations of the advice in the Note,and to obtain help horn a falsework designerwhen the structure they are to build is beyond itsscope or their capabilities.

6 The guidance does not cover the moregeneral hazards which may occur on falseworksites. Sources of advice on some of these aregiven in the publications listed in Appendix E.

7 This document is issued by the Health andSafety Executive (HSE) and was prepared in closeco-operation with the Construction Industry

Advisory Committee (CONIAC) of the Health andSafety Commission (HSC).

Statutory responsibilities

8 The falsework contractor should be aware ofthe need not only to prevent the falseworkcollapsing under load, but to ensure that thoseconstructing and dismantling it may carry outtheir work, so far as is reasonably practicablewithout risk to their health and safety. They mustalso safeguard against risks to the health andsafety of others who may be working on, orpassing by the construction activity. Such riskscould arise for example horn falling materials,wind blown plywood or scaffold battens, noise ortoxic dusts.

9 On sites where there is a main contractor andseveral sub-contractors, the main contractorshould ensure the safe co-ordination of allactivities on site.

10 All those connected with the construction offalsework have duties under the Health andSafety at Work etc Act 1974. Clients, professionaladvisors, main contractors, managing contractors,sub-contractors, and operatives are all expectedto play their part in preventing accidents. Thosesupplying plant or equipment also have aresponsibility so far as is reasonably practicable,to ensure it is safe and without risks to healthwhen properly used.

11 Contractors also have specific duties underthe Construction Regulations (listed inAppendix E). Contractors should be familiar withthese Regulations before commencing on site.

Categories of falsework

12 Falsework varies in complexity from thosewhich can be easily erected and have adequatereserves of strength to carry the applied loads tothose which are complicated to erect and mustbe subjected to close structural analysis. Thisguidance therefore divides them into twocategories.

13 Category 1 falseworks are those which maybe constructed horn sketches derived horn

(a) Are the loads to be applied to the falsework fairlyNO – uniform, such as a beam of constant section or slab of

I uniform thickness?

II YES

I I

NO b) Are the loads within the range shown in the typicalsolutions?

I I I

I YES

No (c) Is the height of the falsework within the range shown

I in the typical solutions?

I 1 I

YES

No (d) Is the site remote from exposed positions such as near

Icoasts or on exposed hills?

I I

II YES

I II

(e) Have assurances been given, supported by your ownobservations, that the falsework will be founded ongood ground unaffected by areas of uncompacted fill,

NO or backfilled cellars etc; or on existing concretestructures of confirmed strength or on rock, densehard packed sands or gravels or firm clays which willnot be liable to flooding during the life of thefalsework?

I 1 I

I Yes

I (f) Are only small items of plant and equipment such asNO small compressors, vibrator motors, etc to be placed

I on the falsework? IYES

(g) Can the falsework be used without special detailing toallow for plant or vehicles to safely pass underneath or - NOclose by it?

IYES

(h) Is any one area of the falsework likely to be erected _ Nofor less than 1 month?

YES

(i) Is the falsework to be erected on ground that will notbe affected by excavation work during the life of the - NOfalsework?

IYES

(j) Is the concrete to be placed in a manner that will notcause shock loads or surges upon the falsework; suchas being dropped from a height, rapidly discharged –NOfrom a ready mixed wagon or which might occurwhen using some types of concrete pumps?

YES

(k) Is the total building height to be less than 20m? - NO

YES

(1) Is the falsework firmly tied to the permanent structureby direct connections and through the stiffness of the – NOdecking?

IYES

(m) Will the set concrete be strong enough to supportitself when the falsework is struck, without the need - NO

I for repropping or backpropping? IYES

Category 1- This GuidanceNote may be used

Category 2- A falseworkdesigner should be

Lconsulted

Table 1

typical solutions, horn proprietary manufacturescatalogues or, where the falsework is very simple,are based on the erection teams previousexperience of many similar successful schemes.

14 Category 2 falseworks are those with specialfactors which may require a falsework designerto make technical judgments, carry outcalculations and/or prepare drawings or sketches.

15 This guidance only deals with category 1falsework. Table 1 sets out the conditions whichwill help to identify whether a falsework isCategory 1 or Category 2.

16 Many sites will include both categories offalsework. Falsework contractors must distinguishbetween areas that are of a different category.Where both categories do occur on one site,there may be an interface problem.

Preparation

17 Table 2 on page 8 is a guide to theparagraphs concerned with the preparations forwork on site. It also provides guidance on thevarious stages which must be considered tomake an orderly start to a contract.

Control documents

18 Before a falsework scheme is prepared all theavailable relevant information that may affect theconstruction and its sequence of loading shouldbe gathered together into three controldocuments. Typical layouts of such document areshown in Appendices Al, A2 and A3. AppendixAl shows a typical layout of a falsework briefwhich should be supplied by the main contractorideally prior to tender. If this document is notavailable the falsework contractors would need toassemble the information themselves.

19 The falsework contractor should visit the siteto gather additional information and prepare asite information and inspection record as shownin Appendix A2. In particular the contractorshould examine the condition of the ground, thelayout of the site and the progress of other workin the area. Should there be any doubt about thecapacity of the ground to carry the weight of thefalsework then the contractor must seek advicefrom the main contractor or a consulting engineer

as is most appropriate. Alternatively where thecontract allows, the falsework contractor couldadvise the main contractor of the loads beingcarried by the falsework standards so that theground may be prepared by the main contractorto carry these loads. One factor that might affectthe load bearing capacity of the ground wouldbe the risk of water flooding the site, causing thesoil under the foundation to be washed out orsoftened. If this is a possible occurance then afalsework designer should be consulted.

20 The exposure of the site and whetherunusually high wind or heavy snow loads arepossible must be assessed. Where such factorscould occur a falsework designer should beemployed.

21 During the site inspection the falseworkcontractor should look for anything that maycause problems in handling equipment andassociated plant. Problems could arise from suchthings as restricted site access, congestedworking areas or overhead power cables.

22 In areas where there may have been previousworkings, the falsework contractor should enquireabout the possibility of buried live services,concealed trenches or old unfilled cellars. Incertain parts of the country caves or cavities canoccur near the surface. These might be expectedin limestone, chalk or soft sandstone areas orperhaps where workings for coal, salt, stone orother minerals have taken place near the surface.Where these occur at a site, the falsework shouldbe regarded as Category 2 and a designerconsulted.

23 The falsework and main contractor shoulddiscuss activities planned for the site but notlisted in the falsework brief which may affect thefalsework eg, will it carry heavy plant? Arevehicle access ways required through it? What isthe programmed erection time for the falsework?Are other works to be carried out near bylikely to pose a risk to its stability? What methodis proposed for placing the concrete?

Detailing

24 The following paragraphs give advice on thedetailing of falsework schemes using typicalsolutions for Category 1 falsework.

RECEIVE INSTRUCTIONS

Are all details, drawings, specifications available intheir latest revision? If not obtain these.

Is a falsework brief available? If not prepare one.1

see para 18

Carry out site inspection. see para 19

Are the ground conditions good with the sitelayout/position uncomplicated and not likely to beexposed to severe local weather conditions? If not

see paras 15 and 19appoint a competent person to prepare the design.

Appoint a competentperson to prepare design

Appoint experiencedsupervisor for closesupervision and considertraining needs

Falsework contractor tonominate falseworkmanager to keep sitefalsework record log

Carry out a normalinspection

Have the materials beenused before? YES Check thoroughly

see para

Table 2Preparing for falsework construction

Is there a main contractor? YES Agree availability of plantsee and facilities andpara 23 programme

Complete site inspectionrecord see paras 18 & 19

YES Appoint a detailersee

para 25

Complete falseworkscheme summary see para 54

Is workforce experienced? YES Appoint supervisorsee paras

60-61

Is the falseworkcomplicated, extensive orare there severalcontractors involved?

YES see paras55-59

Main contractor to appointfalsework coordinator. If nomain contractor, falseworkcontractor to nominatefalsework manager ascoordinator -

I

62

Have the foundations beenprepared as detailed? If not see paras 74-79see that they are prepared.

I Start construction I

Fig 1 Areas where access is required

are to be used,25 Even though typical solutionsit is essential for each falsework scheme to be setout formally either in sketches or in other formsof detail for the benefit of the erection team. Thedetails should draw together all the informationrequired for the construction of the falsework.The title falsework detailer describes the personwho produces these sketches or details andshould therefore be experienced in the type ofwork being undertaken.

26 The falsework detailer should prepare thedetails on the basis of the information containedin the falsework brief and the site inspectionrecord.

27 The detailer should not show proprietarymaterials being used in any other way than thatrecommended by the suppliers or themanufacturers and should mange for thesuppliers’ literature to be readily available forthose working with it. Any special instructionsabout the equipment should be included on thesite sketches. The detailer should consider thelimitations of the proprietary equipment and notextend its use into areas where it is not suitable.When in doubt it is essential to check with thesupplier’s design department.

28 Drawings, sketches or other details should begiven a reference number and dated. If revisedthey should be given a revision letter and thedate of the revision. They should also refer to thesources of the information used in theirpreparation, such as the falsework brief, siteinspection report, drawings, this document ormanufacturers’ catalogues.

29 The detailer should be aware of the types ofmaterials and equipment that are available for theworks.

30 The detailer should note on the informationfor the falsework erection team, the type ofground conditions assumed to be available tosupport the falsework, together with any specificground treatment or preparation necessary tomake it suitable to carry the falsework.

31 Proper consideration should be given toproviding safe means of access and safe placesof work for those erecting and dismantling thefalsework. When part of the falsework is beingused as a working platform, the detailer shouldshow that a minimum width of 600mm isrequired. The edges of the platform from which aperson could fall more than 2m should be

properly guarded with guard rails andtoe-boards as set out in the Construction(Working Places) Regulations.

32 The lacing tubes which tie the standardstogether could act as guard rails if properlylocated. Where no lacing tubes are provided,temporary guard rails should be detailed. Whenthe formwork decking has been placed andpersons are working on it, its edges should befitted with guard rails and toe-boards. Typicallayouts are shown in Fig 1.

33 If any permanent foundations or structures ofconcrete, brick or steel are to be used to supportthe falsework, the detailer should enquirewhether they have been thoroughly investigatedby a suitably qualified person, to ensure that theycan safely carry the falsework loads.

34 The table in Appendix B gives advice on themaximum loads suitable for certain types ofground. It should be read in conjunction with thetypical solutions shown in Appendices C and D.

35 The detailer should specify that all loosematerials, top soil etc, should be removed hornground which is to support the falseworkfoundations. Unconsolidated areas should becompacted by a vibrating roller.

36 The detailer should be aware of the dangerfrom water either softening the ground orscouring out the supporting from under thestandards. On cohesive soils, standing watercould soften the ground, while on non cohesivesoils running water or cross flow could causescour. In either case blinding concrete should bedetailed covering the ground together with anynecessary cut-off trenches or diversion ditches.

37 Falsework base plates should be detailed torest on sole plates which in turn should rest onprepared foundations. These will not be requiredif they rest on permanent works which have beenverified to be capable of supporting the loadsfrom the base plate. Foundations for the falseworkshould normally consist of either lean mixconcrete or a crusher run stone aggregate (orstone graded from 18mm down to dust) laid andcompacted by rolling in 50-75mm thicknesses.See Fig 2.

38 Where bases have to be located along aninclined surface, tapered timber blocks should be

detailed so that the bases are properly seated onthe sole plates. Alternatively swivel basesspecially designed to carry heavy falseworkloads, could be detailed, provided that the detailalso shows a suitable method of securing them tothe sole plates. Lacing tubes should be detailedat the bottom of the standards to resist anytendency of the bases to slide down the plate.See Fig 3.

39 Where the standards are scaffold tubeswhether of ordinary tube or parts of a systemscaffold, they should always be detailed as beingtied together with other scaffold tubes acting aslacing. As a minimum requirement such lacingtubes should be positioned both near the headsand near the feet of the standards.

40 Adjustable steel props should be detailedwith a minimum of a single set of lacing tubesfixed to the inner section of the prop betweenimmediately above the junction with the outer toone third the way up the inner section. Howeverthe distance between either the head or the footof the prop and the lacing tube must not exceedthe maximum unsupported length of standardnoted in the tables for the typical solutions. Noadjustable prop should be detailed at a greaterlength than 3.Om unless a designer has beenconsulted. See Fig 4.

41 Care must be taken when detailing standardsat the edge of a slab, either where the slab formsthe support to the standard or is supported by it.Tolerances should be allowed in the setting outdimensions so that the bearing plate on thestandards will not overhang the slab edge losingsome of its bearing area. Care should be takenthat it will not have to be placed out-of-plumb topick up the slab edge timbers. Timbers to beplaced outside but parallel to the slab edges,should have falsework standards detailed to carrythem. See Fig 5.

42 The falsework should be detailed so that it isstable at all stages of construction both duringerection and when dismantling. This will usuallyrequire each standard to be restrained in at leasttwo directions by lacing tubes which in turn arebraced or tied back to the permanent structure.

43 When scaffold tubes are used as braces orlacings in lengths that need joining, the joints

should standards made of different materials,such as steel and aluminium, be used in thesame falsework.

46 In a birdcage falsework, bracing tubesshould normally be fitted at no greater intervalsthan every sixth leg and extend the full height ofthe falsework. No brace should be set at an anglegreater than 70° or less than 30° to the horizontal.If the lacing tubes can be rigidly tied to a part ofthe permanent structure this may be assumed tobe an effective line of bracing. See Fig 6.

Fig 4

must be specified to be staggered amongst thevarious members. See Fig 6. It is a prudentpractice for any joints in the braces or the lacingtubes to be fitted either with splice tubes orlapped, as well as being connected with sleevecouplers.

44 All couplers should be detailed to be rightangled or swivel couplers. Where necessary theactual model of the coupler may be specified.

45 Where the standards are longer than themaximum unsupported height indicated inAppendices C and D, they should be detailed sothat they are tied together by a sufficient numberof properly braced lacing tubes, at verticalcentres not exceeding the maximum heightnoted. This arrangement is shown on thesketches for the typical solutions. In no cases

47 Most base or head jacks should be detailedto extend by not more than 250mm, unless theyare of a specific manufacture having known loadbearing capacities at greater extensions. See Fig 7.Those with pillars whose diameter is less than25mm should only be extended 150mm beforebeing braced. Where greater extensions cannotbe avoided the jack should be braced in twodirections. See Fig 8.

48 Lacing tubes should be detailed to be fittedwithin a specified distance from the base plate orbearing surface of the head jack. In no caseshould this distance exceed a quarter of themaximum unsupported height of the standard asdescribed by the typical solutions.

49 Where the permanent structure is to be usedto provide anchorage for ties or braces thedetailer should ensure a check has been made ofits ability to safely absorb any forces that mayarise.

50 Falsework should be detailed so that theinstability of one member will not cause adjacentones to become unstable and lead to theiroverturning. Members with a depth to width ratiogreater than 3.0 require restraint to preventoverturning. The width used in calculating theratio should be the width of the units bearingwhere this is narower than the width of the unititself. Care should be taken when detailing howthe ends of these restraints should be secured, toensure that they do not simply pass on anoverturning tendency to adjacent members thatmight cause these also to overturn. See Figs 9and 10.

51 Instability might also occur as a framework isconstructed. The detailer should be aware that a

Fig 5 Use of props at slab edge (lacing tubes omitted for clarity)

high slender structure could be overturned if notgiven lateral support as it is constructed. This is aparticular concern where temporary eccentricloads may be applied or cantilever accessbrackets used before the full dead weights areapplied to make the falsework stable.

52 When several levels of concrete slabs arebeing cast propping may be required to supportthe floors which are to carry the erectedfalsework in some circumstances. However, suchfactors as the sequence of building thefalsework, the loads on this, the age and strengthof the supporting suspended slabs and thepositions of the props themselves could causethe backprops to have detrimental effects on thecompleted parts of the permanent structure.Therefore a designer should be consulted forapproval of any back propping proposals.

53 The detailer should also consider methodsby which the falsework may be dismantled andwhere necessary include details to facilitate thisin the design.

54 After completing the falsework details, thedetailer should sketch and summarise thefalsework scheme. A suitable form for thefalsework scheme summary is shown inAppendix A3. This summary should be checkedto see if a Category 1 falsework is still suitable.The falsework brief, the site inspection record,and the falsework scheme summary should bedistributed to all who need the information.

Co-ordination

55 A person should be nominated to co-ordinatethe various aspects of building the falsework.The main contractor should normally nominatethe co-ordinator as described in BS 5975,especially on sites where there is more than onecontractor involved with the falseworkconstruction. The co-ordinator should carry outthe duties listed in paragraph 59.

56 On smaller sites the duties listed inparagraph 59 should still be carried out but thenominated person could be the falseworkcontractors site supervisor who may perform thisfunction simply be keeping a record log in thesite office. The record log would note theinstructions the site was working to, any revisions

to the original scheme and the authoritysanctioning those revisions. The log would alsorecord who checked the falsework and onwhose decision it was loaded, dismantled orbackpropped. Such a system would be reliableonly where the falsework scheme wasstraightforward and where few persons wereinvolved.

57 The nominated person should have hadexperience of constructing falsework and havebeen instructed in the duties described in thefollowing two paragraphs, and in section 10.2 ofBS 5975. Whenever possible nominated personsshould be trained before taking up their posts onsite.

58 The nominated persons role is to ensure thateveryone concerned with the falsework isworking to the same information, that before it isloaded it has been properly completed and hasbeen thoroughly checked. It is essential that allsite proposals for changes in the design,construction or loading of the falsework aremade through the nominated person to thosewho detailed or designed it. Time must beallowed for all parties to consider the proposalsand respond. Replies or amendments from thedetailer should then be fed back through thenominated person. Where sites are large orwhere there are a number of contractorsinvolved in the construction, all the informationshould be passed on by written instructions.

59 The primary functions of the nominatedperson are to ensure that:

(a)

(b)

(c)

(d)

(e)

all concerned with the construction of thefalsework are made aware of the up-to-datefactors affecting it;

all are working to the most up-to-datedrawings and that these are consistent withthe detailers’ or the falsework designers’instructions;

the falsework details have been checked bya second person;

all are working with the same programmetowards the same loading time and date;

the interface areas between different parts ofthe falsework structures, differentcontractors, or different categories of

(f)

(g)

(h)(i)

(j)

(k)

falsework, have been fully considered anddetailed or specified;

any alterations in construction materials ormethods have been agreed by the detailerand others concerned;

the erected falsework has been checkedbefore loading;

loading permits are issued;

permits for the dismantling of the falseworkare given;

records about the falsework construction arekept including any decisions that altered itssize or layout;

the load on the falsework is not likely to beaffected by any variations made in the layoutof the permanent structure, since thefalsework design was completed.

Site supervision

60 The erection and dismantling of the falseworkshould be carried out by a team who are eitherexperienced and familiar with the equipment orwho are instructed and closely supervised.Adequate training must be provided for all theworkforce especially when an unfamiliarfalsework system is to be used.

61 The person supervising the erection anddismantling, must be competent having previousexperience of this type of work. This personshould be available on site at all times or whensignificant parts of the construction process are inhand. The falsework contractor’s site supervisorshould be supplied with all the relevantinformation concerning the equipment on site, sothat this may be safely used.

Materials on site

62 Most falseworks are constructed frommaterials or equipment which have been usedpreviously. Therefore it is important that theseshould be carefully examined before each use toensure they are of a suitable quality andcondition. A checklist for such an examination isgiven in Table 3.

63 The falsework contractor must use identicalmaterial and equipment to that specified in the

details and in the manner shown. Should thematerials or equipment be unavailable nosubstitution should be made without theagreement of the detailer who should be givenprecise information about the proposedreplacement items. When considering any suchrequest the detailer may have to seek furtheradvice horn a designer about the proposedsubstitute parts.

64 When not in use all equipment should beneatly and carefully stacked on pallets or bearerswith timber battens between any tiers. It is alsoimportant that the items should be handledcarefully to prevent undue damage, and notthrown to the ground or tipped into heaps.

65 Each time equipment is erected it should begiven a visual check to see that it is undamaged.Any defective items should be immediatelyremoved to an area designated for damagedequipment.

66 Site management should not overlook thepossibility of defective equipment or materialother than that specified being delivered to site.Therefore all materials should be checked beforeuse, whether or not they are new or claimed tohave been refurbished. New materials should begiven a nominal visual inspection, while usedmaterial should be checked by a thorough visualexamination of a proportion of the componentsand a visual inspection of the remainder to seethat they appear to be of the same quality.

Timber materials

67 Timber products should be checked foroverall soundness to discover rot, splits damageand whether any part has been reduced in sizeby burning, notching, splits or by holes beingdrilled or cut through it. Preformed memberswith nailed, butted and glued joints should beexamined to see if they are still sound. Timberproducts which will be exposed to severeconditions for a long period, should beconsidered for treatment by preservatives.Plywood should be of an external quality andwhere intended for use in a typical solution,should be at least 18mm thick. Structural timbermembers should be at least of grade SC3material. Further information on the visualinspection of timber to check if it is of this grade

Checklist for the site inspection of used equipment

(a) The equipment when delivered should be a (h) where units have been repaired, they shouldcomplete system for its designed use; be to a standard equal to the other units in

(b) where the materials are delivered fromdifferent sources and/or of differentmanufacture, they should be cheked toensure they are compatable;

the delivery batch. Rewelded areas shouldbe checked for excessive weld metal thatmight prevent the use of the member or be a hazardto those handling it. Where this is sothen the weld should be smoothed off;

(c) items of proprietary equipment should bechecked to see that they are in a condition (i) all moving parts on the units should besuitable for the work; checked for ease of movement. Screw

(d) where necessary prior to delivery theadjustments should be able to operate alongtheir full thread and telescoping movements

equipment should have been grit blasted to should be unhindered. In addition all movingremove old concrete or mortar to allow any parts should be properly oiled;welds to be properly inspected;

(e) units should have been checked for overallstraightness and that they are true to shape.Any bearing plate, box or tubular memberswith noticeable bends, buckling or dents,should not be included in the delivery;

(j) units should have adhesive labels givinginformation about fixing and loading wherethis would be normal for a similar new item.Where such labels are worn and difficult toread, new ones should be fixed;

(f) welded connections should be sound (k) it is a legal requirement that all necessaryparticularly those around any fittings which instructions are ready available forare intended to support the weight of the proprietary systems including informationunit; about the safe methods of erection, stacking

(g) bracing members which are part ofand handling, limits of use and safe workingloads, with full translation of any instructions

individual units should be intact with their not written in the English language.end properly fastened into the member as inthe original specification;

Table 3

may be obtained in the TRADA leaflet ‘Simplifiedrules for the inspection of secondhand timber forload bearing use’.

Steel or iron products

68 Steel or iron products should be checked tosee whether their cross section has beenmarkedly reduced by corrosion. If so, they shouldnot be used until it has been confirmed by anengineer or designer that they still have asufficient reserve of strength. Sections that havebeen bent, buckled, welded or drilled for bolt orservice holes may have had their strengthcharacteristics seriously affected and should notbe used until expert advice has been sought.

Miscellaneous materials

69 Alloy members should be checked forsignificant pitting and galvanic corrosion.

70 Fibre glass or plastic units should bechecked for damage that may have weakenedtheir edges and reduced the bearing area.

Proprietary items

71 The falsework contractor should ensure thathired equipment is suitable for the purposesintended, and is safe to handle and use. Thesuppliers should have given any informationnecessary to identify the various components, andwhere appropriate the correct method of erectionand dismantling. Any factors that might limit thesafe use of the equipment should have beenclearly stated.

72 Framed units and proprietary items, such asadjustable steel props and centres, must beexamined, be in good condition and bereasonably clean. Items such as high tensilebearing pins should only be replaced byidentically sized high tensile components. Weldsmust be thoroughly checked especially thosesupporting cantilever arms whose failure wouldcause a sudden and dangerous collapse. Movingparts should be oiled and checked to see theyoperate fleely. Bent members in times should bereplaced if they are more than a quarter of thethickness of the member out of line. Buckled endbearing or base plates should be replaced,bearing end plates on flooring centres should becomplete and flat. When items cannot be

cleaned or repaired to a satisfactory standard onsite, they should be sent back to the. depot.

73 Proprietary units of different manufactureshould not be mixed in the same area of workunless the suppliers have agreed that they arecomparable.

Erection

Foundations and setting out

74 The details, sketches or drawings showingthe layout of the falsework should state theassumed ground conditions and the erectionsupervisor should check if these assumptions arestill valid.

75 All top soil, loose fill and other unsuitablematerial should be removed from the ground areaintended as the site for the falsework.

76 The foundation should be set out carefully inaccordance with the details. Time and effortspent on thorough and careful preparation atfoundation level will in most cases, produce anoverall saving in time. It will also help to ensureboth the continuing stability and the safe erectionof the falsework structure.

77 Sole plates to support the falsework standardsshould be accurately laid out on the foundationsboth to line and spacing. Wherever possible thesole plates should be laid horizontally. In certaincases, depending on the type of falsework beingused, it may be necessary to control therelationship of the level of one sole plates withanother. Where the sole plates are laid up aninclined surface, each length of plate should befully butted against the next in any particular run,and the lower end of the run should fully restagainst some form of anchor block to ensure thatslipping cannot occur. In all cases, the sole platesshould be fully bedded into their foundations.See Fig 3. Where the incline exceeds 1 in 4 asindicated in Fig 3, the falsework should beregarded as Category 2.

78 Base jacks or plates supportiing the falseworkstandards should be set out along the centre lineof the sole plates. Where the falseworkframework is relatively light and might be easilydisplaced, then the base plates should be nailed

Fig 11

Fig 12

to the sole plates. See Fig 2. Final tightening ofthe base jacks should only take place after thebracing to the falsework has been fitted.

79 When tapered blocks are being used to givea full bearing to base plates resting on inclinedsole plates these should be firmly nailed to thesole plates. They should be cut from soundtimber and carefully shaped to match theinclination of the sole plate. The grain in theblock should be arranged to be in line with thebase plate, ie horizontal.

The framework

80 The standards should be carefully erected tobe vertical, and any rakers inclined at the anglespecified by the detailer. If they have beenproperly set out then simply sighting along therows will show any that significantly deviate hornline or verticality.

81 All horizontal lacing members must be fittedto the standards at the specified heights usingright angled couplers. All types of verticalmembers suffer a reduction of load carryingability if used in unsupported lengths greaterthan specified.

82 Every attempt should be made to erectscaffold standards and adjustable props verticallywithin the tolerance shown in Fig 11.

83 It is most important that loads are placed onthe standards directly over or equally about theircentrelines, and these loads are then passed ontothe foundations through their centre withindetailed tolerances. Failure to do this will result inthe standards having a reduced load carryingcapacity. For this reason bearers and joists heldin forkheads on the standards should be carefullywedged to hold them centrally with the wedgestightly driven home and nailed. See Fig 12.Normally when timber joists are placed lapped togive continuous runs, no single lengths of timbercan be used over more than three standardswhile still maintaining concentric loading onthese.

84 Where forkheads are not being used andjoists are supported on flat end plates theyshould be either nailed through the holesprovided in the plates or secured in some otherway to ensure they always remain central over the

standard and have adequate restraint to preventthe joist rolling off the prop head. This could bedone by framing the joists together as if in apanel.

85 Edges of completed falsework from which aperson might fall more than 2.00m, should beguarded by handrails and toeboards, exceptwhere work is being carried out from or at thoseedges. See Fig 1.

86 When sections of the falsework are lefttemporarily incomplete they might still be usedby others as a means of access or as a workingplace. Warning notices should therefore be fixedto them stating they are unsafe.

Checking

87 A checklist for Category 1 falsework isshown in the leaflet which is a companion to thisGuidance Note.

88 All falseworks should be carefully checkedduring their construction and have a thoroughfinal check prior to being loaded. The contractorshould bear in mind that if a falsework is notchecked during construction, rectification of earlyerrors found by a final check could be difficult orimpossible to achieve without dismantling.

89 It would be beneficial if the final check wasearned out by some experienced personunconnected with those who constructed thefalsework, as their fresh observations may pick uperrors unnoticed by the erection team. After finalchecking using a formal checklist, some form ofwritten permit to load should be issued even ifthis only consists of a note in the site diary.

90 After casting suspended slabs it is importantnot to load them with heavy materials orequipment, such as brick packs etc other thanthose described in the falsework brief, until theconcrete has gained sufficient strength.

Dismantling

92 Care should be taken to ensure that thefalsework structure remains stable at all timesduring dismantling. Where the falsework couldbecome unstable because of the nature of itsconstruction and sequence of dismantling,temporary guy ropes or raking struts should befitted to adequately secure it.

93 When decking is being struck, sentries orwarning notices should be posted to keeppersons clear of areas where formwork materialsmay fall. Formwork and falsework should becarefully dismantled and not stripped byremoving lower members to produce a suddencollapse.

94 Striking should be carried out in accordancewith a pre-planned sequence which has beenagreed with the detailer, and agreed with thepermanent works designer. Where decking unitsincorporate “quick strike” facilities, the personstriking the units should note that the deckingcorrectly drops into the secondary restingposition at each pillar before striking the next inthe planned striking sequence.

95 Thought should be given to the means ofaccess and places of work required during thedismantling process. In some cases they will bedifferent from those required during the erectionof the falsework. For instance, during erectionmaterial may be placed horn above but duringdismantling will have to be stripped out frombelow.

91 The sequence of dismantling should be asnoted by the detailer or as required by thepermanent works engineer.

Appendix A Suggested layout ofcontrol documents

This appendix contains examples of documentsthat should be used to bring together theinformation about the falsework. They have beendesigned for the specific situation where a maincontractor is employing a falsework sub-contractor. Complete sets of the documentsshould be issued to those who requested thefalsework, those directing its construction, the co-ordinator, and any contractors working with thefalsework (eg, main contractor steel erectors,concretors, formwork contractors).

Falsework brief

Information to be given to the falseworkcontractor

General

1 Estimate or contract no.

2 Name of main contractor

3 Address of site

4 Name, address and telephone no of consultingengineer/architect ..

5 Section of site where the falsework isrequired .

(Give levels and grid references as appropriate). -

6 Description of the work to be carried out andthe limits of the falsework contractors work areaand responsibilities ..

(Specify the point of the construction wherefalsework contractor is to start work, what is to beprepared beforehand, and what work, if any, is tobe undertaken by others, eg ground made readyby main contractor and waffle formers laid byformwork contractor). ..

7 List of permanent work drawings issued tofalsework Contractor with schedule of drawingnumbers and revision number ..

8 Other load such as heavy plant that could beplaced on the falsework, apart from thepermanent structure shown on the drawings :

9 List of plant and equipment the maincontractor will make available to the falseworkcontractor by mutual agreement ..

10 Details of any openings, clearances etcrequired through the falsework ..

11 Programmed erection dates and finish dates :

12 Preferred concreting sequence ..

13 Any other information ..

Note Some of this information may not beavailable at the time of awarding the falseworkcontract. In such cases the brief should indicateif the information will become available at the siteinspection stage (see Appendix A2), when themain contractor could be on site.

Site information and inspection record

To be completed by the falsework contractor (anysoil survey reports should also be noted togetherwith information from trial pits where these havebeen dug).

1 Nature of the ground on which the falseworkis to stand (check that there is no markedvariation with the information given in thefalsework brief).

2 Liability to flooding, proximity of water coursesand ditches.

3 Location of old workings, trenches cellars etc.

4 Access to site, will this restrict the type ofvehicles using it? (eg perhaps because ofloading, width, overhead power lines or nature ofthe environment?).

5 Requirements of cranes or other plant to coverthe working area. (Confirm who will supply this).

6 Exposure of site (note possible excessive windloads) or other environmental factors:

7 Any other information

Falsework scheme summary

To be completed by the falsework detailer as asummary of the scheme prepared.

1 Location of the section of falsework detailed:

2 Vertical loading

(a) from permanent structure

(b)

(c)

(d)

from any plant and equipment 10 Drawing numbers sketches and specifications

from construction loadsprepared by the detailer.

To be completed by the falsework contractor (inAllowance for self weight of conjunction with the detailer)falsework/formwork

3 Method and rate of pouring the concrete

4 Category of falsework (ie 1 or 2 as para 15 ofthe GN).

5 If Category 2- Name of designer.

6 Description of the foundations.

7 Type of falsework system to be used includingspacing and height of standards.

8 Maximum load estimated to be on eachstandard.

9 What formwork system has been assumed.

11 Experience of workforce necessay for theproposed system - Note of any training that isproposed before the falsework is constructed.

12 Degree of supervision required.

13 Name, address and telephone numbers ofdetailer.

14 Name, address and telephone number ofdesigner if employed.

15 Name, address and telephone number ofnominated a co-ordinator. (If it is not proposed tonominate a co-ordinator explain how the functionis to be carried out).

Appendix B Suggested contractor is expected to build the falsework on

foundation details to suit various other conditions then a designer should be

ground conditionsconsulted. It is intended that the Appendixshould be read in conjunction withAppendix C or D and therefore the references toconditions A, B and C referred to below, arefurther described in those appendices. In

This appendix gives advice on how a foundation producing this Appendix it was assumed thatfor a standard should be built off various ground condition A could support at leastground/support conditions. It only covers the 5000 kg/m2, condition B at least 2500 kg/m2 andmore reliable types of condition and if a condition C, 1200 kg/m2.

Ground/support conditions Actions to be taken Foundation details

(a) Existing structures or foundations. Submit the proposed layout and loadings Use timber sole plates if required by mainon the standards to the consulting contractor who should specify theirengineer and obtain confirmation that minimum length.these loads can be carried.

(b) New foundations or structures. Submit proposals as above to main Use timber sole plates if required by maincontractor or the consulting engineer and contractor who should specify theirobtain confirmation that loads can be minimum length.carried.

Submit falsework load and layout to the Use timber sole plates if required by mainmain contractor. contractor who should specify their

minimum length.

Detail the foundation for the falseworkerectors.

Submit falsework loads and layout to the Build to the contractor detail whichmain contractor and request details of the should specify their minimum length.required foundation.

OR

Ground/support conditions Actions to be taken Foundation details

(e) Submit falsework loads and layout to the Build to the contractor detail whichtruck main contractor and request details for should specify the length of the sole

the foundation plates.

Firm clays or reasonably wellconsolidated sands or gravels

OR

Detail the foundation for the falseworkelectors. Note: At least three

standards to besupported off eachlength of sole date

(f) Submit falsework loads and layout to the Build to the contractors details which. .Tarmac on rolled hardcore, total

main contractor and request details for should specify the length of the sole

thickness at least 200 mm the foundation. plates.

OR

Detail the foundations for the Min. 50 mm thick 275 x 70 mm timberfalsework erectors after first checking lean concrete sole plate, length asthe area is sound. projecting 70 mm condition B in

minimum Appendix C or DNote: At least threestandards are to besupported off eachsole plate

(9) Submit falsework loads and layout to the Build to the contractors details whichmain-contractor and request details for should supply the length of the solethe foundation plates.

OR

Detail the foundation for the falsework Min 50 mm thick Min 275 x 70 mmerectors after first checking the area is lean mix concrete thick timber solesound.

Note: At least threestandards to besupported off eachlength of sole plate

(h) Hard firm ground of stiff clay or well Submit falsework loads and layouts to Build to the contractors detail whichcompacted sands or gravels. the main contractor and request details should specify the minimum length of sole

of the foundation. plates.

OR

80 mm minimumDetail the foundation for the falsework . . . . . . Minimum 275 x 70erectors after firstsound.

checking the area is truck rolled stone mm timber soleor lean mix plate, length asconcrete base 10C condition C inmm minimum L

Appendix C or Dprojection

Note: At least threestandards are to besupported off eachlength of sole plate

Where the ground does not appear to reach thequality indicated in this table or where there isany difficulty in compacting it because of the softnature of the ground experienced advice must

Appendix C Typical solutions forfalseworks to support in situconcrete beams

This Appendix gives some typical solutions forfalseworks that are intended to carry insituconcrete beams up to l.Om deep either whenthey are individual units or where the beamfalsework also supports an area of suspendedfloor slab.

The solutions are based on one general layoutthe falsework. The sizes of the members vary

for

according to the load to be carried, the type ofmaterials to be used, and the height of thefalsework up to a maximum height of 3.Om at theforkhead, as shown in the tables. In additioninformation is given that allows some variation in

be obtained. Such advice should also beobtained if the ground could be adverselyaffected by water or by freezing.

the size of the foundation detail supporting thefalsework standards, depending on the type ofground as listed in Appendix B. Finally, workedexamples are given showing how to use thetables.

It is stressed that the information given in thegeneral layout for the typical solution, the designtables, the worked examples and in Appendix Bare all inter-related. No details purporting to be atypical solution should be prepared which onlyuses parts of the information in the Appendix,perhaps blending this with other sources ofinformation, without first getting advice from afalsework designer. Detailers must similarly workonly within the range of loads and typicalexamples shown in the tables, unless a designeradvises that it is safe to do otherwise.

General arrangement of falsework for the support of insitu concrete beams. This detailto be read in conjunction with the table and worked example on the on the following pages

NOTES1 The detail has been produced on the assumption 3 The Tables and details assume that only goodthat 18 mm thick, exterior quality plywood will be used quality structural timbers will be used to support theto support the beam soffite. concrete.

2 Either scaffold tube, proprietary tube or telescopic 4 It is assumed that the falsework will only beprop may be used for the standards, except that as expected to carry the concrete load for less than fournoted on the Table, props should not be detailed as weeks. If a longer time is anticipated then theCategory 1 falsework for the heaviest loaded examples. falsework is Category 2.

5 The width of the falsework and scaffold framesupporting the insitu beam D must be at least H

3.6 Where the Table says that the minimum sole platelength is NA, this means not applicable and thefalsework is Category 2.7 Timbers assumed to be simply supported.Secondary timbers are to be nailed to the beamsoffite plywood.8 NA in Tables means that the case is not applicablefor Category 1 falsework.

Tableinsitu

of typical solutionsconcrete beams

for Falseworks to support

Loading

Load not Examples of the form ofto exceed construction which could give this

load:-

Span ofplywooddecking= spacingof secondary

1200 kg/m 0.50 305

0.80

1800 kg/m

0.90305

125

300

405

2400 kg/m305

3.90125

—405

400 350

3000 kg/m240

3600 kg/m

4.50

Note = for standards marked - * - only use adjustable props when laced together- ** - do not use adjustable props.

second timbers Primary timbers Max. Minimum sole plateunsupported length (mm)

size oflength of

Max. Size of Max.assuming 25 mm MIN

standard width of sole platesection span of section span of(mm)

mmember (mm) member(M) (M) Condition Condition Condition

A B c

50 x 75 .500 75 x 100 .950 2.75 0.500 0.600 1.40050 x 100 .700

100 x 75 flat .800 75 x 150 1.450 2.75 0.500 0.900 2.200

50 x 75 .45050 x 100 .650 75 x 150 1.150 2.75 0.500 1.100 2.600

100 x 75 flat .70075 x 200 1.550 2.50 0.700 1.400 N.A.

50 x 100 .55075 x 100 .70075 x 150 1.200

50 x 75 .500100 x 75 flat .700 75 x 150 1.000 2.750 0.600 1.200 N.A.75 x 100 .800

75 x 200 1.350 2.250 0.800 1.600 N.A.

50 x 100 .550 *

75 x 100 .650 75 X 225 1.500 2.250 0.900 1.800 N.A.75 x 150 1.050 *

50 x 100 .70075 x 100 .850 75 x 150 .900 2.50 0.700 1.400 N.A.75 x 150 1.400

75 x 200 1.200 2.00 0.900 1.800 N.A.

50 x 100 .50075 x 100 .600 75 X 225 1.350 2.00 1.000 2.000 N.A.75 x 150 .950 *

75 x 200 1.100 2.00 1.000 2.000 N.A.75 X 225 1.250 1.75 1.100 2.200 N.A.

50 x 100 .500 *

75 -x 100 .55075 x 150 .900

The contract is for the construction of a falseworksystem to support 110 mm deep slab carried by350 x 500 mm deep overall beams at 3.5 m centres.

The storey height in the building is 3.5 m.

Alternative 1 Design a system where the slab formwork is carried on the beam side shutters.Step 1 From the examples listed in the Table, theappropriate design row is the one for loads notexceeding 2400 kg/m. Bottom half of the row.

Step 2 Plywood decking. The max span of theplywood is 405 mm, this therefore is the maximumspacing of the secondary timbers.

Step 3 Secondary timbers. 50 x 100 timbers; thesemay span up to 550 mm but should be placed to suitthe beam width.

Assumptions - the contractor wishes to use 50 x 100and 75 x 150 or 75 x 225 timbers which are available insufficient quantity of a suitable quality.

Step 4 Primary timbers. These will be spaced at 550mm and when using 75 x 225 timbers may span up to1.50 m.

Step 5 Max unsupported height of standard. With75x 225 timbers spanning 1.50 m, this height is limitedto 2.25 m. Either scaffold tube or telescopic props.

Step 6 Sole plate lengths. These may be a minimumlength of either 0.900 m for condition A or 1,80 mfor B. Condition C is not Category 1.

Alternative 2 Design a system where only the beamis carried, ie the slab will be carried by anindependent falsework.

Step 1 From the examples listed in the Table theappropriate design row is the one for loads notexceeding 1200 kg/m.

Step 2 Plywood decking. This is to span 305 mmwhich will be the spacings of the secondary timbers.

Step 3 Secondary timbers. 50 x 100 timbers may spanup to 0.70 m, ie this is the max spacing of the primarytimbers.

Step 4 Primary timbers. 75 x 150 members,these may span up to 0.95 m.

Step 5 Max unsupported height of standards. Whenusing 75 x 150 primary timbers at 0.95 m span, maxunsupported height is 2.75 m.

Step 6 Sole plate lengths. These are for

condition A -500 mm

condition B -600 mm

condition C - 1.400 m

Appendix D Typical solutions forfalsework to support insituconcrete slabs

This Appendix gives some typical solutions forfalseworks that are intended to carry insituconcrete slabs of weights up to the equivalent of300m thick solid concrete.

The solutions are based on one general layoutfor the falsework. The sizes of the members inthis layout vary accordingly to the load to becarried, the type of materials to be used and theheight of the falsework as shown in the tables,up to a 3.00m maximum height at the forkhead.The size of the primary timbers is used to decidewhich table should be used.

In addition information is given that allows somevariation in the size of the foundation detailsupporting the falsework standards, dependingon the type of ground as listed in Appendix B.Finally a worked example is given, showing howto use the tables.

It is stressed that the information given in thegeneral layout for the typical solution, the designtables, the worked examples and in Appendix Bare all inter-related. No details purporting to be atypical solution should be prepared which onlyuses parts of the information in the Appendix,perhaps blending this with other sources ofinformation, without first getting advice horn afalsework designer. Similarly detailers must workcompletely within the range of loads and typicalexamples shown in the tables unless a designeradvises that it is safe to do

General arrangement of falsework for the support of insitu concreteto be read in conjunction with the table and worked example on the

otherwise.

slabs. This detailfollowing pages

NOTES:

1 Secondary timbers have been assumed to be fullycontinuous therefore they must have their ends lappedat least 450 mm, and the position on the laps staggeredin relation to adjacent lengths. End timbers in a row ofsecondary members should be cantilevered over thelast support by at least one fifth of maximum span.Timbers are also to be nailed to the plywood.

2 The detail has been prepared on the assumptionthat 18 mm thick, exterior quality plywood will be usedto support the slab soffite, even where trough andwaffle formers are to be used.

3 Either scaffold tube, proprietary system scaffoldtube or telescopic props may be used for standards,except that as noted in the Tables props should not be

detailed for Category 1 falseworks in the most heavilyloaded examples.

4 The Tables have been prepared on the assumptionthat only good quality structural timbers will be used.

5 It is assumed that the falsework may only beexpected to carry the concrete load for less than fourweeks. If a longer period of time is anticipated thenthe falsework is Category 2.

6 Where the notes about the sole plate length in theTables says NA, this means ‘not applicable’ and thefalsework is Category 2; ‘ns’ means not suitable as thesize of timber gives unsuitable spans.

7 Primary timbers are assumed to be simplysupported.

Appendix D Table of typical solutions for Falseworks to supportinsitu concrete slabs.

Note standards marked - * - use adjustable props only when laced together.

LOADS - not exceeding - (ie combined dead and live loads)

450 kg/mz 550 kg/mz

100 mm thick solid concrete I 150 mm thick solid concrete

Span of 18 mm thick plywood(ie spacing of secondary timbers

610 mm 610 mm

Details of secondary size (mm) 50 x 75 50 x 100 75 x 100 75 x 150 50 x 75 50 x 100 75 x 100 75 x 150timbers span (m) 0.95 1.30 1.60 2.45 0.85 1.15 1.45 2.20

1

Max. span of primary (m) 1.05 0.90 0.80 n.s. 1.00 0.85 n.s. n.s.Max. unsupported height of

(m) 2.75 2.75 2.75 - 2.75 2.75 -

Condition A 0.50 0.50 0.50 - 0.50 0.50 -Minimum sole — —plate length Condition B 0.50 0.60 0.60 - 0.50 0.60 -

(m)Condition C 1.10 1.30 1.50 - 1.20 1.40 - -

Max. span of primary (m) 1.65 1.40 1.25 1.00 1.55 1.35 1.20 0.95

Max. unsupported height of standard (m) 2.75 2.75 2.75 2.75 2.75 2.75 2.75

Condition A 0.50 0.50 0.50 0.60 0.50 0.50 0.50 0.60

Minimum sole plate length Condition B 0.70 0.80 0.90 1.10 0.80 0.90 1.00 1.20

(m)Condition C 1.80 2.00 2.20 N.A. 1.80 2.10 2.40 N.A.

IMax. span of primary (m) 1.90 1.65 1.50 1.20 1.80 1.55 1.40 1.15

d e l a y e d h e i g h t o f ( m ) 2.75 2.75 2.75 2.50 2.75 2.75 2.75 2.50*I I

Condition A 0.50 0.50 0.60 0.70 0.50 0.50 0.60 0.70Minimum sole — -– Iplate length Condition B 0.80 1.00 1.00 1.30 0.90 1.00 1.10 1.40

— - .(m) Condition C 2.00 2.40 N.A. N.A. 2.10 2.40 N.A. N.A.

I I ,

Max. span of primiary (m) 2.50 2.15 1.95 1.55 2.35 2.05 1.85 1.4

Max. unsupported height of (m) 2.75 2.50 2.50* 2.25* 2.75 2.50 2.25* 2.25*

Condition A1-

0.60 0.70 0.70 0.90 0.60 0.70 0.80 0.90M i n i m u m s o l e — —plate length Condition B

t

1.10 1.30 1.40 1.70 1.10 1.30 1.50 1.80(m)

Condition C N.A. N.A. N.A. N.A. N.A. N.A. N.A. N.A.

700 kg/mz 950 kg/m2

I 200 mm thick solid concrete I 300 thick solid concrete

I 405 mm 405 mm

50X75 5OX1OO 75 X1OO 75 X 150 150 X 75 50 x 100 75 x 100 75 x 150

0.95 1.25 1.60 2.40 0.80 1.10 1.35 2.10

0.85 n.s. n.s. n.s. n.s. n.s. n.s.

2.75 - 2.75 -

0.50 - 0.50 -

0.60 - . - 0.60 -

1.40 - 1.50 -

1.30 1.15 1.00 0.80 1.20 1.05 0.95 0.75

2.75 2.75 2.75 2.50 2.75 2.75 1.75 2.25*I I

,

I 0.50 0.50 0.60 0.70 I 0.50 0.60 0.60 0.80

1.00 1.10 0.80 10.90 1.10 1.20 1.50

1.90 2.50 N.A. N.A. 2.30 N.A, N.A. N.A.

1.55 1.25 1.20 0.95 1.35 1.15 1.10 0.90

2.75 2.75 2.50 2.25* 2.75 2.75 2.50* 2.00*I I

I

0.60 0.70 0.80 10.60 0.60 0.70 0.90

1.10 1.10 1.30 1.60 1.10 1.20 1.40 1.80

N.A. N.A. N.A. N.A. N.A. N.A. N.A. N.A.

2.00 1.75 1.55 1.25 1.85 1.50 1.45 1.15

2.50 2.25* 2.25* 2.00* 2.50* 2.25* 2.00* 1.75*

0.70 0.80 0.90 1.10 0.70 0.80 1.00 1.20

1.30 1.50 1.70 2.10 1.40 1.60 1.90 2.30

N.A. N.A. N.A. N.A. N.A. N.A. N.A. N.A.

Example showing use of the table of typical solutions

The contract is for the construction of a falsework to Stage 1support a 250 mm thick insitu concrete slab. Thestorey height of the building is to be 3.80 m.

Assumptions. The contractor wishes to use 75 x 225 Stage 2and 50 x 100 timbers which are available in sufficientquantity of a suitable quality.

Stage 3

Turn to Tables. From the examples given inthe Table the appropriate design column isfor loads not exceeding 950 kg/m2.

Secondary timbers. In the 2nd vertical columnat this load, 50 x 100 mm secondary timbersmay span up to 1.10 m when spaced at405 mm c/c (ie max span of plywood).

Primary timbers. With secondary timbers atmax span, on page 5 the span of the 75 x 225:primary timber may be 1.50 m maximum.

Stage 4

Stage 5

Height of standards. When secondary andprimary timbers are at their max span; themax unsupported height of the standards is2.25 m which can be constructed fromscaffold tube or telescope props if lacedtogether.

Sole plate design. The sole plates should beat least 0.80 m long (condition A) 1.60 m long(condition B). Condition C, this case is notCategory 1 falsework.

Appendix E Statutoryrequirements and referencesThis Appendix lists some of the documentswhere further advice can be found, which maybe of concern to those building falseworks. Alsolisted are the principle Regulations or legislationthat deals with this topic.

1 Statutory requirementsHealth and Safety at Work etc Act 1974Factories Act 1961Construction (General Provisions)Regulations 1961Construction (Working Places) Regulations1966Construction (Lifting Operations) Regulations1961Construction (Health and Welfare)Regulations 1966Construction (Metrication) Regulations 1984Woodworking Machines Regulations 1974Abrasive Wheels Regulation 1970

2 Sources of further advice(a) Those concerned with the design and

construction of temporary structures shouldmake themselves familiar with the followingpublications:

British StandardsBritish Standard Code of Practice 5973Access Scaffolding

British Standard Code of Practice 5975Falsework

British Standard 5268 Strutural Use ofTimber

Guidance Notes

GS 2 Metrication of Construction SafetyRegulations

GS 15 General access scaffolds

GS 31 Safe use of ladders, step ladders andtrestles

PM 28 Working platforms on forklift trucks

GS 42 Tower scaffolds

(b)

(c)

(d)

(e)

TRADA - Simplified rules for the inspectionof secondhand timber for load bearing use.

When arranging a safe system of work thefollowing publications should be useful:

Guidance Notes

GS 5 Entry into confined spaces

GS 10 Roofwork prevention of falls

PM 9 Access to tower cranes

Health and Safety at Work booklet No 47-Safety in the stacking of materials.

Where working with plant and equipment:

Guidance Notes

PM 14 Safety in the use of cartridgeoperated tools

PM 16 Eyebolts

PM 17 Pneumatic nailing and stapling tools

PM 21 Safety in the use of woodworkingmachines

PM 22 Mounting of abrasive wheels

PM 24 Safety at rask and pinion hoists

PM 27 Construction hoists.

Health and Safety Guidance Booklets

HS(G)16 Safety in working with lift trucks

HS(G)l 7 Safety in the use of abrasive wheels

HS(G)19 Safety in working power operatedmobile work platform.

When working with or near electricity:

Guidance Notes

GS 6 Avoidance of danger from overheadelectric lines

GS 24 Electricity on construction sites

PM 32 The safe use of portable electricapparatus.

When there could be dangers from fire ortoxic materials:

Guidance Notes

GS 8 Articles for substances for use at work

CS 4 The keeping of LPG in cylinders andsimilar containers.

CS 6 The storage and use of LPG onconstruction sites

EH 7 Petroleum based adhesives in buildingoperations

EH 35 Probable asbestos dust concentrationsat construction processes.

CIRIA Report No 16 Safe use of chemicalson site.

Health and Safety booklets: Guidance

HS(G)l Safe use and storage of flexible foampolyurethane.

HS(G)3 Highly flammable materials onconstruction sites.

HS(G)18 Portable grinding machines - controlof dust.

Printed in the UK for HMSO 10M 6/87

(f) Other general duties to thethe public:

GS 7 Accidents to childrensites

workforce and to

on construction

Code of Practice 4 under section 16 of theHSW etc Act - Health and Safety (First Aid)Regulations 1981

Health and Safety booklets: Regulations

HS(R)5 The notification of accidents anddangerous occurrences

HS(R)6 A guide to the HSW Act

HS(R)9 A guide to the WoodworkingRegulations 1974

HS(R)l 1 First aid at work.