1.1 Safety requirement
All temporary works operations are required to address the provisions of:
(a)The Health and Safety at Work etc
(b)The construction Regulations.
Inadequate design of temporary works and other forms of bad practice can result in loss of life or injury.
Attention is drawn to the Company Statements of Safety policy, both general and relating to temporary works and to the Company Standing Instructions and
Project instructions giving procedures appointing the falsework co-ordinator for supervising the construction of temporary works and the authorization for loading.
In the absence of any standard instruction or the company statements of safety policies the works shall be progressed in conformity with the relevant IS on safety
aspects (See cl. 7 of this section)
IS 14687 Guide lines for falsework for concerete structures:
IS 4014 (Part I & II) Scaffolding
“Any temporary structure used to support a permanent structure while it is not self-supporting”.
And formwork is defined as:
“The section of the temporary works used to give the required shape and support to poured concrete. It consists primarily of sheathing material (e.g.
wood, plywood, metal sheet or plastic sheet) in direct contact with the concrete, and joints or strength that directly support the sheathing”.
These definitions apply to insitu concrete and precast concrete structures, structural steelwork erection and the formation of brick arches and similar situations.
The largest use relates to insitu concrete structures, in which formwork is a key element, and represents a substantial portion of the cost of the finished product.
1.3. SPECIALIST SERVICES AVAILABLE
A service for the design of temporary works associated with all types of building and civil engineering projects shall be had from Consultants / structural Division,
including specialist services for the design of falsework and formwork.
2.1 Checking and supervision
With the attention given to falsework during the past few years a good deal of improvement has resolved in designed schemes.
ADEQUATE EXAMINATION OF SUB-CONTRACTOR SCHEMES AND CHECKING FOR SUFFICIENCY BEFORE ANY FALSEWORK IS LOADED IS THE MAIN
CONTRACTORS RESPONSIBILITY UNDER THE HEALTH & SAFETY ACT.
The prime concern remains with sub-contractors dealing with run of the pre cast slab formwork, where rule of thumb methods are frequently used.
A typical check sheet and a “permit to load” are shown in Figs. 9.1 and 9.2. See your Company Standing Instructions or Project Instructions for the procedures to
see on your particular project. Refer also to IS 14687
In the case of access scaffolding, do not allow this to be used until the person responsible for its installation has certified its safe condition for loading. This is
usually given in the form of a handing over certificate issued by the scaffolding contractor / the in charge of scaffolds.
Irrespective of the firm responsible for scaffolding it is required to display boards indicating the status of the scaffolding viz. “FIT FOR USE” (a GREEN display
board) or “NOT FIT FOR USE” (a RED display board)
In the case of firms who are the Scaffold Contractors, a typical certificate is shown in Fig. 9.3 and the following notes apply.
a) the person signing the Handing Over Certificate on behalf of the scaffolding contractor must personally have inspected the structure.
b) Any faults discovered by the person charged to inspect the structure must be corrected before the certificate is issued. You must not allow scaffold to be
used until the corrections have been completed.
c) The person in your team who accepts the certificate must also be competent and in a supervisory position.
A basic list of points to watch out for when inspecting a scaffold structure is given in para 3.2.
FALSEWORK CHECK LIST - Ref. No.
SITE: PROJECT No.
Structure details : Temporary works
Ref / Drg. No. Carried out Witnessed Date
No. by by
1.Design Brief Reference
2.Support structure Design
5.Support structure Design Check
6.Formwork Design Check
7.Foundation Design Check
9.Structure upto 10 M height
10.Structure over 10 M height
11.Inspection for partial loading
12.Pre-loading Inspection &
certificate to load
13.Approval to dismantle
Fig. 9.1 – Example of falsework check list.
FALSEWORK CHECK LIST INSPECTION & PERMIT TO LOAD Ref. No.
SITE: PROJECT No.
Structure details : Drg. No.
Location / Section :
BS 5975 Check Item . Approved Date
50.2 (a) 1. Current & approved drg. complied with.
2 Correct and serviceable materials used
50.2(b) 1 Setting out
2 Ground preparation (strata as in Drg.)
3 Suitable soleplates & bases
4 Inspect for settlement on bases
5 Bedding and erosion protection
6 Slope base supports
7 Secure Chocks etc.
8 Base plates centered
9 Base extension & bracing if required
50.2.(c )1 Ties / rakes fitted as in Drg.
2 Upright plumb
3 Joints in vertical members
4 Spacing & level of lacing lifts
5 Bracing members in all planes as in Drg.
6 OR Effective restraints
7 Forkheads aligned & braced as necessary
8 Bearers spliced, central wedged & nailed
9 Beams bearing correctly & secured
10 Web stiffners & lateral restraint
11 Pins, Bolts, Clips, etc fitted correctly
12 Scaffold couplers tightened
13 Ladders tied, platforms, guardrails &
Toe boards fixed to regulations.
Bridge bearing fixing bolts accessible if
Release required before striking
Approved / NOT Approved to load / partially load (……………………………….) the above falsework.
Fig. 9.2 – Example of falsework inspection check sheet and permit to load
HANDING OVER CERTIFICATE – SCAFFOLDING
Description of section
Fig. 9.3 – Example of Handing Over Certificate.
3.2 Basic checks for scaffold inspection
At ground level walk round the perimeter of the scaffold and check for:
(i) subsidence of the ground
(ii) cavities underneath sole plates
(iii) dislocation of base plates
(i) rectify with adjustable base plates
(ii) fill with concrete
(iii) restore in place
At ground level stand back in front of each standard and check for:
(ii) any signs of buckling in four lifts.
(i) and (ii)
stop using scaffold in the affected section until made good.
(c ) Horizontal bearing
From ground level check the position of ledgers and transoms in the lowest three to four lifts. The first lift is of particular importance.
Vertical distance between horizontal bracing in the first lift must not be greater than in subsequent lifts.
Replace any missing bracing
(a) Diagonal bracing
From ground level check that:
a. transverse bracing to alternate pairs of standards is fixed either to ledgers or directly to standards.
b. Facade bracing is fixed to transoms with right angle couplers and extended from the ground level.
Action: As in (c ) above.
(b) Scaffold ties
Check the position and fixing of all scaffold ties:
i)Only once tie should be temporarily removed and this must be replaced before removing another.
ii)The distance between ties in a vertical or horizontal plane should not exceed 8.5 m within the limits of the tabled area.
iii)A two lift ‘tied’ raker tube from the scaffold base in equal to one tie.
iv)A two lift ‘tied’ taker tube from the scaffold base in equal to one tie.
v)The end 3 m of a scaffold may be left untied provided the scaffold is required and tied on the return. If the return is dismantled then ties to the standing 3 m
portion will be necessary.
vi)All the tubes should be connected to the scaffold and bridles with right angle couplers.
vii)Lashing ties to ring anchors may be used provided adjacent transoms are butted to the building face to prevent inwards movement.
viii)In certain cases the ends of butting tubes should have plastic protection caps to prevent rust staining to the building face.
See Table 9.1 – The frequency.
Replace any missing tie.
Type of Type of Ties which will not Ties which may be
Scaffold tie be removed as temporarily removed
agreed with client as agreed with client
un sheeted Through
independent Box or
up to 50m high Anchor Every 40 Sq.m. Every 32 Sq.m.
Reveals Every 22 Sq.m. Every 22 Sq.m.
Sheeted Through, Box
up to 25 m high Anchor Every 32 Sq.m. Every 32 Sq.m.
Unsuitable unless Unsuitable unless
Reveals supplemented supplemented
Unsheeted putlog Through Every 40 Sq.m. Every 32 Sq.m.
Scaffold up to
50m high Reveals Every 22 Sq.m. Every 22 Sq.m.
Hoist Towers Through, Box
or Anchor Every floor level Not to be removed
Bird cage Through, Box Every 40 Sq.m. on
Scaffold or Anchor all vertical faces Not to be removed
Table 9.1 – The frequency
At each working lift check the decking:
(i) the working platform should be closely boarded, each board having at least three supports.
(ii) Boards should be butted and they should oversail their last support by at least 50 mm but no more than 150 mm lapping is permissible if bevel
pieces are provided to prevent tripping.
(iii) Precautions should be taken to hold down decking in high winds.
Nail steel straps to hold boards together
(iv) additional scaffold board to be placed between the inner standard and the face of the building when the open space exceeds 300 mm.
Do not use scaffold until (i), (ii) and (iv) are rectified.
(g) Guardrails and toe boards
At each lift check:
i) both guardrails and toe boards should be fixed to the inside of the
outer standards and remain in position before decking is removed.
ii) Guardrails should be fitted at not less than 0.9 m and not more
than 1.15 m above the decking.
iii) Toe boards should be at least 150 m high above the decking and
the clear spacing between the guardrails and the boards should
not exceed 0.75 m.
The decking must not be used until conditions (i), (ii) and (iii) are
complied with. Stacked material needs special consideration.
(h) Standards ledgers, transoms and diagonal bracing.
At each working lift check the scaffold structure:
Make sure that the members are not supporting any other loading,
vertical or horizontal, coming from external structures like cranes, hoists
loading towers, rubbish chutes, etc. These structures should be
designed as independent load carriers with separate ties to the building.
(i) Safety note, fans and weather protection
At each working lift check:
When incorporated in the scaffold the relevant detailed drawings should be available from the sub-contractor for checking purposes.
At each working lift check:
Every ladder must stand on a firm and even base and be supported only
by the stiles. The ladder must be securely held in position at top and
bottom by fixings to the stiles. The ladder should project at least 1 m
above the landing platform. Inspect at rungs for soundness.
(k) Raising the working lift.
(i) make sure that vertical and horizontal joints in tubes are staggered.
(ii) Not more than one lift can be erected
(l) Material of scaffold components
No mixing is permitted of steel and alloy scaffold components of the same
designation. Handrails must be made of the same materials as ledgers.
The final arrangement to be checked by a competent person.
4. BASIC CONSIDERATION IN FORMWORK
(a) The forms determine the shape and accuracy of the finished product as well as the surface appearance. It therefore requires competent attention if the most
economic, suitable and safe solutions are to be achieved.
(b) Construction must be adequate to resist the loads of the wet concrete, without unacceptable deflection. In the case of soffit formwork an additional allowance
of 2 KN / sq.m. must be allowed for self weight, operations and heaping of concrete. Check propping down through the structure to a firm foundation.
(c) Joints between elements must prevent grout or water loss, which causes honeycombing in the finished concrete.
(d) Design and detailing must be such as to allow dismantling without damage to the forms or the concrete itself.
(e) Accuracy in manufacture and assembly must relate to the specified accuracy of the finished structure or to the information given in BS 5606 – “Code of
practice for accuracy in building”.
(f) Ensure that the location of bolt holes, soldiers, connectors, etc., do not clash with the positions required for service entries or other inserts for ducts, holes,
cast-in items, etc.
(g) Removable panels are left for blowing out debris before concreting commences.
(h) Check surface of shutters are sealed, joints taped (if required), mould oils or release agents all applied before steelfixing starts.
(i) Check the location and quality of any concrete kickers. These should be sound, well formed and of the same inherent strength and degree of compaction
as the surrounding main part of the structure. For new kickers a bolt-on addition to the top of a shutter will facilitate pouring the kicker at the same time as the main
Do not permit the practice of forming these kickers some time after the main concrete pour by using a trowel and a bucket containing an unknown
mix of concrete.
5. FORMWORK PREPARATION AND TREATMENT
5.1 Specification and selection
The formface must be suitable to achieve the specified finish. See the specification.
In the absence of specified formwork preparation and treatment regimes, such as the use of proprietary mould oils or chemical release agents, agree with the
employing authority the type of treatment on the basis of its proven ability to consistently produce concrete finishes of the specified quality and durability.
The effective performance of any type of form treatment is dependent on the following:
- Type of form face used
- Consistency of methods of form cleaning and preparation
- Time delays between application and concrete placing
- Ambient climatic conditions
trials are a contractual requirement
Whichever mould oil or chemical release agent is selected for trial, it is important that the use of the treatment is strictly in accordance with the manufacturer’s
Once established and adopted for use, do not change formwork treatment materials and practices in any way unless ordered otherwise by the employing authority.
If the surface finish of the exposed concrete is a significant factor in any contract, it would be prudent to contact. Before contract work starts. Experience gained
on previous work is always being collected and there is in hand a programme of trials related to this subject.
Refer also to the manufacturers’ literature and to Concrete Society “Notes on formwork release agents and coatings” for further details.
5.2 Absorbent surfaces
Untreated timber absorbs the release agent giving a grain patterned finish. If it is essential to overcome this problem, give one of the following pre-treatments
before use, a once-only operation:
(a) One or more full coats of the normal release agent.
(b) A suitable barrier paint or varnish (on a dry surface, preferably factory applied).
(c) A suitable wax.
Prior to concreting for the first time, and for all subsequent pours, give a normal application of the chosen release agent.
Patches of barrier point or varnish may wear off with use and cannot be renewed because of the absorption of release agent into the form face, resulting in a
blotchy appearance to the concrete.
5.3 Non-absorbent surfaces
The release agent may tend to migrate and dry up, especially where all emulsion is used. This happens frequently, e.g. on bridge decks, where the time between
application and concrete placing may be prolonged. The condition is also aggravated by drying winds, strong sunlight and rain. Neat oils with surfactant and
chemical release agents are best in these circumstances and should be applied immediately before having reinforcement to avoid contamination.
5.4 Climatic conditions
Emulsions are easily removed by strong sunlight, drying winds and rainfall. Neat oils with surfactant stay on much longer due to their greater penetrative qualities
on absorbent surfaces. Chemical release agents are good provided the surface is reasonably dry before application. They are therefore effective on steel and
plastic faced forms.
Do not apply release agent to wet formwork. Some of the materials with surfactant or chemical release agents have de-watering properties. For general use, it is
sufficient to remove as much moisture as possible from the surface prior to re-treatment.
5.5 Concrete placing
Release agents are sometime removed by abrasion during placement of concrete in tall narrow columns, on inclined form surfaces or by mixes of low workability.
Filling ports and the use of trunking can assist in reducing the risk, especially with high or inclined forms. Seek further advice where the appearance of the work is i
mportant. Wax treatments are best to use. Neat oils, and or chemical release agents, are also satisfactory in these circumstances
5.6 Formwork face features.
Any projection from the formwork face that prevents free movement of concrete at the interface required careful treatment to avoid defects in finish. Pronounced
horizontal features in a wall need particular attention.
There are many problems posed by patterned concrete finishes, the majority of which need to be dealt with on an individual basis. Seek specialist advice before
the forms are designed.
5.7 White concrete
White concrete is easily discoloured by mould oils therefore use specially formulated high quality release agents. Seek specialist advice before a choice is made.
5.8 Quality of finish
Where quality or finish is of importance, experiment shall be conducted with sample and trial panels to establish the most satisfactory release agent well before
Some types of release agents are susceptible to frost action so provide suitable protective storage facilities.
5.9 Methods of application
(a) By Hand
Too much is as bad as too little. A thin evenly applied film worked well into the form surface is all that is needed. Do not use brushes and brooms. A sponge or
mop or, ideally, a cellulose floor mop of the type which enables the head to be squeezed out will provide superior results. Oil puddles will cause the concrete to
(b) By spray
Best results are obtained in soil conditions. Airless spray equipment is usually better than compressed air sprays. However, the most common type uses a hand
pressurized container coupled to a lance by a flexible hose. Only use spray units designed for release agents. Garden sprays are not durable and may have
5.10 Cost of release agents
This is a very small proportion of the total cost of the formwork, and its omission is a false economy. The cost of applying a release agent exceeds the cost of the
agent itself and ease of application is therefore of great importance.
Sometimes the more expensive products provide greater coverage and greater ease of use, thus using less labour, and may be more satisfactory in providing the
5.11 Surface retarders
These are applied to the formwork surface before concreting in a similar manner to release
Retarders react with the cement in the concrete against the formwork face and retard the set of the surface layer. This enables the concrete surface to be
removed easily, often by brushing, after the formwork is struck.
Surface retarders are used in some cases to assist in the production of an exposed aggregate finish. It is very difficult to obtain a completely consistent
appearance by this method due to the many variables which can affect the degree of retardation. They can be very satisfactory, however, for construction joint
faces, where their application to the face of the stop end formwork enables the surface of the joint to be easily prepared to receive the next pour.
Formwork, once treated with retarders cannot, in general, be used for other work. However use of latex retarders which produce a dry film may allow the form to be
cleaned and used elsewhere.
6. STRIKING OF FORMWORK.
Formwork should be designed so that striking may be carried out safely and without damage to the concrete. The length of time that forms remain in place
depends on the strength development of the concrete and the loads to which it will be subjected on removal of the formwork, and will vary with different parts of the
structure. In general the formwork can be removed earlier with richer mixes and with rapid-hardening cement.
Forms can be removed sooner in warm weather than on cold weather. Formwork must not be removed without specific instructions from the designated falsework
co-ordinator, who should make sure the concrete is strong enough to carry its own dead load and any other loads upon it. BS 8110 states that formwork
supporting insitu concrete in flexure may be struck when the cube strength is 10 N/mm or twice the stress to which it will be subjected, whichever is the greater.
This is normally continued by tests on cubes or cylinders cured under similar conditions as the concrete in the member to be struck (see BS 8110).
Do not remove formwork or propers without the agreement of the designated falsework co-ordinator.
In cases of doubt, it is advisable to err on leaving the forms in place too long, especially with beams and slabs.
IS 14687: Guidelines for falsework for concrete structure
IS 2750 : Steel scaffolding
IS 4014(Part 1011): Safety regulations for scaffolding
Code of practice for steel tabular scaffolding.
BS 5258: Structural use of timber, Part 2 : Code of practice for permissible
Stress, design, materials and workmanship.
BS 5531: Code of practice for safety in erecting structural frames.
BS 5973 Code of practice for access and working scaffolds and special
Scaffold structures in steel.
BS 5974: Code of practice for temporarily installed suspended
Scaffolds and access equipment.
BS 5975: Code of practice for falsework.
BS 8120: The structural use of concrete.
Circular Statement of safety policy on falsework.
Booklet 610 Health and Safety for all persons on site
Booklet 630 Overload power lines, underground cables,
Telephones and gas services:
Building Advisory Service (BEC)
Construction Safety Manual, Section 21.
Health & Safety Executive (HSE)
Check list for supervisors and charge-hands erecting falsework
Guidance Note PM27: Construction hoists
HS© 32 Safety in flasework for insitu beams and slabs.
Construction Summary Sheets
SS1: General legal requirements
SS2: Use of ladders
SS3: General access scaffolds
SS4: Safety in roof work
SS10: Tower scaffolds
SS13: Construction goods hoists
International Powered Access Federation (IPAF)
Guide to mobile elevated work platforms.
CITB Guide to practical scaffolding
Report No. 71, formwork striking times
Technical Note 80: The distribution of loading on props to soffit formwork.
Works Construction Guide. Access scaffolding.
The Concrete Society
Notes on formwork release agents and coatings.