Bangladesh national building code, 1993

Bangladesh National Building Code

Chapter 7, para 3: Safety in Construction

3.1 GENERAL
3.1.1 Scope
The provisions of this chapter shall apply to the safety of life and property during construction of various parts of a building or any other structures.
Nothing stated herein shall be construed to nullify any rules, regulations, safety standards or statutes of the local authority. Corporations, or those contained in the various Acts of the Government of Bangladesh. The specific rules, refutations and Acts pertaining to the protection of the public or workmen from health and other hazards wherever specified by the local Authority/Corporation etc. or by the Act/Ordinance of the Government shall take precedence over whatever is herein specified.
3.1.2 Safety of Workmen
Helmets conforming to BDS 1265 and BDS 1266 shall be worn by the workmen and other personnel at all times during the work.
Safety goggles of accepted standard (BDS 1360) shall be used by individuals engaged in drilling, cutting, welding and all such works which cause hazard to the eye. The welders and gas cutters shall be equipped with proper protective-equipment like gloves, safety, boots, aprons and hand shields havng filter glass of accepted standard and suitable to the eyes of the particular worker.
3.1.3 Site Precautions
Construction site shall be delineated, in absence of boundary walls, by-fences During the erection of tall building nylon net net shall be put around the building periphery 3 to 4 metres below the working level.

Warning signs shall be displayed, where necessary, to indicate hazardous areas like high voltage zone, area of no smoking etc. Hand lamps shall be of low voltage, preferably 24V. All electrically operated hand tools shall be provided with double earthing.

3.1.4 Site Amenities
Toilet facilities shall be provided at all construction sites. If sewer connection is not available, temporary wells shall be used. The wells shall be provided with proper covers.

The toilet facilities shall be located at a corner of the site so as to avoid any obstruction. Protection from bad weather and falling object, and proper privacy shall be provided to the toilet users.

Temporary toilets shall be dismantled, all wells filled up, and the whole area made level, dressed and restored back to proper grade at the end of the project. All temporary sewer connections shall be removed and the sewer capped.

Washing facilities provided at the site shall be connected to the available running water supply.

Drinking water shall be supplied to the site. In absence of any water supply facility at the site, hand tube wells shall be sunk to meet the requirements of drinking and washing.
Numbers of the sanitary and plumbing facilities required in a construction site shall be regulated by the 1965 Factories Act, and Sec 1.2.5.

3.2 EXCAVATION AND FOUNDATION WORK 3.2.1 General
The requirements of this section shall be satisfied in addition to those of Sec 3.12 of Part 6 for all excavation and foundation works.
Design of foundations shall ensure safety of -the Workmen, the neighbours and the adjoining structures during construction. The possibility of movements unconnected with the application of load shall be considered and steps taken to avoid any damage. Filling around high foundation piers shall be brought up in a way as not to endanger their stability.
The process or excavation fitting in pumping etc. shall avoid .endangering the strength or stability of the partially completed structure. The partially completed structure shall be capable of carrying loads previously taken by temporary works which, as part of the construction procedure, have to be transferred before the completion of the work.
Excavation with intervals on any site shall be avoided. If such excavation is unavoidable, the excavated site shall be properly fenced and warning signals given in accordance with Sec 3.2.11. Excavation of interrupted or temporarily suspended construction shall be either backfilled or barricaded.
3.2.2 Excavating Machinery and Tools
Heavy equipment, such as excavating machinery, shall be kept away from the trenches by a distance at least equal to the depth of trench to a maximum of 6 metres. All excavating tools shall be kept far away from the edge of trench.
3.2.3 Excavated Materials and Surcharges
Excavated materials shall be kept away from the edges of the trench to provide a clear berm of safe width. Where this is not feasible, the design of protection for the trenches shall include the additional load due to the materials.
Proximity of buildings, piles of lumber, crushed rocks, sand and other construction materials, large trees, etc. may impose surcharges on the side of the trench to cause bulging, sliding, etc. Additional protective measures shall be taken to support the sides of the trenches under these conditions. The objects creating such threat shall be removed if possible before excavation starts.

3.2.4 Ground Water
Where deep excavation is required, the location of water-bearing strata shall be determined and the water pressure observed to take necessary precautions. Direction of natural drainage shall be determined to facilitate the design of intercepting drains to prevent the influx of ground water.

In areas where the ground water or soil contains constituents in amounts sufficient to cause damage to cement or buried metals, a chemical analysis of samples of ground water and soil shall be obtained and necessary precautions taken.

Basements or pits below ground water level, which rely on the weight the superstructure for their stability against floatation, shall be pumped day and night. Protective filters shall be used during heavy pumping in excavations. The water shall be drawn away from the excavation rather than through the ground towards the excavation.

3.2.5 Ground Condition Adequate precautions shall be taken during excavation in loose soil deposit and loose boulder.
Where portions or the foundation are underlain by soft materials or where the layers of such materials vary in thickness, the assessment of allowable bearing pressure shall require a settlement analysis.

Site investigations shall be sufficiently extensive to ensure that significant variations in strata thickness are detected, IF required, either the resistance of the inclined or jointed strata shall be increased or the foundations shall be carried deep enough to prevent sliding.

Precautions, against pockets of poisonous/ dangerous gases including protection to the workmen, shall be taken during deep excavation. Effect of climatic variations and variation in moisture content of the soil shall be constantly monitored and precautions taken immediately, when necessary.

3.2.6 Overhang, Slopes and Cavities
Overhangs in the trenches shall be supported by props. Use of heavy machinery shall be avoided under or over this area.

Where climatic or other conditions may result in deterioration of the sides of excavation, consideration shall be given to their support and protection. During excavation, adequate protections justified by established method of analysis shall be taken to prevent slope instability.

3.2.7 Blasting and Vibration
Blasting for foundation of buildings is prohibited unless special permission is obtained from the Authority. Where blasting technique is to be used, an analysis for the stability of slopes shall be carried out and steps be taken accordingly.

Attention shall be given to the geological strata of the site to ensure that it is not liable to transmission of ground vibration to areas where it may cause damage to property or the ground.

After blasting, overhangs or loose boulders shall be cleared off the site. In all excavation works, precautions shall be taken to eliminate/reduce vibration generated by adjacent machinery, vehicles, railroads, blasting, piling and other sources.

Appropriate authorities shall be notified in advance of any blasting operations when these are to take place close to public roads and railways. Also see Sec 4.3.

3.2.8 Health Hazards during Excavation
Mechanical ventilation shall be provided where gases or fumes are likely to be present in trenches. All personnel working there shall be provided with protective respiratory equipment. All trenches/tunnel shall be provided with emergency exits (see Sec 3.10.2.6 and Sec 3.10.3).

The precautionary measures provided shall meet the requirements of the local health authority. The owner shall ensure that all precautionary measures have been taken and been inspected by the Authority prior to commencement of such work.

3.2.9 Piling and Deep Foundation
All piling and deep foundation operations shall be supervised by a competent foreman. He shall also be responsible for the precautionary measures to be taken.

For work during night, lighting of at least 100 lux intensity shall be provided at the work site. In excavations deeper than 1.5 m, ladders, ramps or other means of escape, and staging shall be provided.
3.2.10 Working in Compressed Air
Filtered compressed air shall be supplied to a working chamber sufficient to provide 0.3 nr^of fresh air per minute per person at the pressure in the chamber. Means-for the escape of-foul-air;-as-well-as circulation-of fresh air in the chamber, shall be. ensured. Hot drinks shall be supplied to workmen employed in compressed air after leaving the chamber.

No person shall carry any flammable materials inside-the-air-lock and- nobody shall-be allowed to smoke, inside. Only approved type of lamps and torches shall be used. Lighting of at least 4.5 lux intensity shall be provided.
Methanometer shall be used to detect hazardous gases. Samples of air inside the well shall be taken every eight hours and tested for the presence of hazardous gases and for deficiency of oxygen. In case any hazardous gas is detected, it shall be immediately reported to the engineer and the work in the compressed air stopped.
The pressure in the chamber, in the first minute, after starting compression shall be increased to 35 kPa. It shall not be further increased until the lock attendant has checked whether or not there are complaints of discomfort. The pressure shall then be increased at a rate of 65 A:Pfl/min. If any person complains of discomfort, the proceeding compression shall be immediately stopped and the person evacuated unless he fells comfortable again in a reduced pressure.
In case-of airlocks where blasting is done, the workmen shall be permitted, to-start work. only after an inspection by a competent professional found it to be safe. Air required for pneumatic tools shall be cooled and purified in the same way as air for working chamber.
Every man lock shall have a minimum head room of 1.8 m and at least 0.85 m3 of space per person. It shall be suitably equipped with an accurate pressure gauge, clocks, and efficient means to convey visible or nonverbal signals to the lock attendant outside. All electrical installations inside the airlock shall be of flameproof type.

All equipment shall be thoroughly inspected after every 45 days of working, and every time it is shifted 'and reinstalled, and-certified-to be in a safe working condition by -a. competent person. A record of all such inspections shall be kept in a register.
The receiver shall 'be 'capable of maintaining the working-pressure for at least four hours. Adequate access through the bulk-heads-and-sufficient ladders shall be provided. Escape routes in tunnels shall be in the corner. Whilst any person is in a working chamber, the door between such chamber and any man-lock providing egress towards a lower pressure shall be kept open.

No person shall -be-a-working- chamber-under- pressure where the wet bulb temperature exceeds 29°C measured by a thermometer. using nontoxic materials.

No person shall be employed on -work in compressed air unless -under the -supervision of. a -person experienced in such work. No person shall be employed where the pressure exceeds 120 kpa unless he has, within the previous four weeks been examined and certified to be fit for employment in compressed air. If a person is suffering from cold in head, sore throat, earache etc., he shall not be employed in compressed air. Where the pressure exceeds, a suitably constructed medical-lock shall be provided. It shall have two chambers, and doors fitted with bulls eyes and air valve. The lock shall have couch, blanket, dry woolen garments, food etc. The medical lock shall be supplied with air, free of oil and carbon monoxide, and capable of raising the pressure from to 520 kPa in 5 minutes.

3.2.11 Fencing Warning Signs and Watchman
Excavation and piling sites 'shall be fenced all around. No trespassing shall be allowed. Sufficient number of notice boards, danger signs, flashing lights etc. shall be provided in the area. When excavation is done on a road, alternative passage/route with adequate signs, notice board and lights shall be provided. If necessary, watchmen shall be employed as an additional precautionary measure to prevent any accident, specially during the night.

3.2.12 Adjoining Properties and Service Lines
Where bored or driven piling works are to be carried out in the vicinity of old structures which are likely to be damaged, tell-tales shall be fixed on such structures to monitor their behavior while piling is in progress; timely precautions shall be taken against any adverse effect. Steps shall be taken, if necessary, to increase the general stability of the construction site or the adjoining site(s), before new structures are erected. In all cases, the possible effect of slopes and excavation of foundation stability shall be carefully investigated. Before excavation or pile driving, information on the location of underground utility connections shall be obtained from the relevant authorities. Probable extent of all damages due to pile driving to adjoining structures or service lines shall be ascertained in advance of operation; pile driving shall be planned accordingly.
If excavation involves cutting through existing land drains, they shall be carefully diverted into the ground drainage system. In addition, all other precautionary measures required by Sec 1.5 and 4.1 shall also be taken.

3.3 PILE RIG
3.3.1 Erection of Pile Rig
The frame of the rigs shall be structurally safe for all anticipated dead, live and wind loads. Whenever the structural strength is in doubt, suitable test shall be carried out by the engineer and the results recorded. No pile driving equipment shall be used until it has been inspected and found safe. When two or more pile drivers are used at the same location, they shall be separated by a distance at least equal to the longest leg of either rig. Pile drivers shall be firmly supported on heavy timber sills, concrete beds or other secure foundations. If necessary, pile drivers shall be adequately guyed. Rigs not in use shall be supported by at least three guys to withstand wind, storm, gales and earthquake.

3.3.2 Operation of Pile Rig
Access to-working platforms and top of pulley shall, be provided by ladders working, platforms shall be protected from wind and rain. Ladder in regular use in tall driven piling rigs, or rigs of similar nature, shall be securely fastened and extended for the full height of the rig.
Exposed. gears flywheels etc, shall be fully enclosed. Motor gearing, transmission, electrical wiring and other parts of a hoisting machine which are sources of hazard should have proper safeguards. To operate energized electrical installations insulating mats and wearing apparel such as gloves, etc. shall be used. Sheaves on pile drivers shall be guarded against workers drawn into them accidentally.
No steam or air driven equipment shall be repaired while it is in operation or under pressure. Steam and air lines shall be controlled by easily accessible shut-off valves. These lines shall consist of armored hose or its equivalent.
The hose of steam and air hammers shall be securely lashed to the hammer so as to prevent it from whipping if a connection breaks. Couplings of sections of hose shall be additionally secured by ropes or chains. When not in use, the hammer shall remain in dropped position held in place by a cleat, timber or other suitable means.
Hoisting appliances shall be provided with means to reduce the risk of accidental descent of the load. Adequate precautions shall also be taken to reduce the risk of any part of suspended load becoming accidentally displaced. Care shall be taken to prevent the hammer from missing the pile. Loads shall be adequately counter-balanced, and the tilting device secured against slipping. Precautions in the form of securing the legs shall be taken to prevent a pile driver from overturning it a wheel breaks. Stirrups or other means shall be provided to prevent the rope from coming out of the top pulley or wheel. Hoisting ropes on pile drivers shall be made of galvanized steel. Pile drivers shall not be erected in proximity to electric conductors. When electricity is used as power for piling rig, only armored cable conforming to BDS 901 and other relevant standards shall be used. The cable shall ob thoroughly waterproofed.

3.3.3 Piles
Piles shall be prepared at a distance at least equal to twice the length of the longest pile, from the pile driver. Workers-employed in. the, vicinity-of pile drivers shall wear helmets- conforming to BJDSAl265 No steam air. shall be released until all workers are at a safe, distance.
Piles shall be so slung that they do not swing or whip round. A hand rope shall be fastened to a pile hoisted to control its movement. Long piles and heavy sheet piling should be secured against falling.
While a pile is being guided into position in the leads, workers shall not put their hands or arms between the pile and the inside guide or on top of the pile. Inclined piles shall rest in a guide while driven.
Maximum length of bellies shall be 9 m. Bellies shall not be less than 50 mm in diameter at any place and shall spread to 75-200 mm in diameter at the top depending on the class of bellies. Each belie shall be legibly and indelibly marked with information on the species of timber, suppliers name, class of belie etc. Whenever required, butt ends of bellies shall be preserved with creosote-fuel oil mixture 50:50. The driving end of a belie post shall be provided with an iron ring or cap. When creosoted bellies are driven, adequate precautions, such as the provision of personal protective equipment and barrier creams, shall be taken to prevent injury from splashes of creosote.
3.3.4 Inspection and Tests
Pile driving equipment shall be inspected by an engineer at regular intervals not exceeding four months. A register shall be maintained at the site for recording the results of such inspection. Pile lines and pulley blocks shall be inspected by the foreman before the beginning of each shift for any excess wear or other defects.
Defective parts of pile drivers, such as sheaves, mechanism slings and hose shall be repaired by only competent technicians and duly inspected by foreman in-charge of the rig. The findings of such inspection shall be recorded in the register.

For every hoisting machine, chain, rig, hook, shackle, swiveland pulley blockused inhoisting or supending the safe working loads shall be ascertained. Every hoisting machine and all rears shall be marked with the safe working loads and the conditions under which it is applicable.
Tests shall be performed in case of doubt and half of the tested load shall be taken as the safe working load. No part of any machine or any gear shall be loaded beyond the safe working load.

3.4 CONSTRUCTION OF WALLS
3.4.1 General
The height of wall constructed per day shall be restricted to ensure that the newly constructed wall does not collapse due to the lack of strength in the lower layers. Adequate number of expansion joints shall be provided in long walls to prevent crumpling.

3.4.2 Ladder
3.4.2.1 Setting of Ladders : Rails of ladders shall extend at least 1m above the landing and shall be secured at the upper end. As an alternative, there shall be adequate handhold at landing, or side guys with anchorage at the bottom.
To prevent slipping a ladder shall be secured at the bottom end or held by a person at the time of use. A lean-to-ladder may have a maximum angle of 75° with the horizontal. Ladders shall be provided with non slip bases on slippery or sloping floors. Ladders used in strong wind shall be securely lashed in position.
A ladder shall neither be placed against window, pane, sashes or such other fragile or easy yielding objects, nor in-front of-doors-opening towards it. If set up in driveways, passageways or public walkways, it shall be protected by barricades. Ladders shall not be supported on any insecure base, e.g. scaffold, planking over trenches etc.
3.4.2.2 Use-of Ladders: All ladders shall-be-.constructed-of sound-material, and shall be capable of carrying the design loads. No ladder with a missing or defective rung, or supported on nails only, shall be used. A dropped ladder shall be inspected prior to reuse.
Ladders shall not be used as guys, braces or skids, nor in horizontal position as runways and catwalk. They shall not be generally overcrowded. Ladders shall not be spliced; when unavoidable, splicing shall be done only under the supervision of a foreman.
A user shall place his feet near the ends of the rungs rather than near the middle, and face the ladder when using it. Both the hands shall be used in climbing a ladder. Leaning more than 300 mm from the side in order to reach another area from a single setting of the ladder shall not be allowed; the ladder shall be shifted to the required position.
All joints in the ladder shall be-properly constructed. Where necessary, handrails shall be provided to the ladders. A brace shall be attached at the middle and supported from a no yielding fixed object if a ladder shows tendency to spring. Excessive deflection of ladders shall be prevented by stiffeners. Metal ladder shall not be used close to electrical equipment or circuits. They shall be marked with CAUTION DO NOT USE NEAR ELECTRICAL EQUIPMENT signs. Overhead protection shall be provided for workers working under a ladder. Wooden ladder shall be inspected at least once in 6 weeks for damage and deterioration. Close visual inspection is recommended in preference to load testing. This condition is particularly applicable to rope and bamboo ladders where fraying of ropes and damage to bamboo is likely to occur.
3.4.3 Opening in Walls
Before making an opening in an existing wall, adequate supports against the collapse or cracking of the wall portion above the opening or roof or adjoining walls shall be provided. Staging shall be of full length of the wall opening.

Wall opening barriers and screens shall be capable of withstanding the intended load. Every chute wall opening or any other wall opening from which there is a vertical drop of more than 1200 mm shall be guarded by barriers.
The guard shall be removable, hinged or otherwise mounted. The guards shall be kept in position regardless of the use of the opening. In addition, n grab handle shall be provided on each side of the opening. The opening shall have a minimum 25 mm high sill.
3.4.4 Projection from Walls
Formwork provided for' horizontal projections out of .the wall shall not be removed till walls, or other stabilizing construction, over the supporting edge of the projecting slabs providing protection against overturning are constructed.
3.5 CONSTRUCTION OF FLOORS 3.5.1 General
Platforms, catch ropes, nets etc. shall be provided during the construction of roofs. Precautions shall be taken to employ the correct technique or hoisting materials, to use hoists of sufficient strength for the quantity of stores to be hoisted, and to prevent overloading and overturning of hoists or buckets, etc.
Where, the floor of one store is to be used for storage of materials for the construction of roof, it shall be ensured that the total load does not exceed the capacity of the floor.
3.5.2 Use of Sheets
It shall be ensured that joints in corrugated galvanized iron or asbestos, cement sheets are kept secured in position and sheets do not slip. Walking on asbestos cement sheets shall not be allowed. Tiles shall not be left loose on the roof. Injury to passers-by due to breakage of glass or plastic sheets shall be prevented. During wet conditions, work on sloped roof shall not be allowed unless the foreman decides that the roof is not as slippery as to pose any risk. In slopes of more than 30' to the horizontal, ladders, waist-tie etc. shall be used.
3.53 Platforms
Working platform required according to the type of roof shall be provided. Additional-precaution shall be taken to construct the platform with sound material secured and fixed, and checked from from time to time fortune throughout the period of construction.

Sec 1.4.2, Sec 1.4.3, See 4.1.6 and See 4.2.5.1 shall also be followed additionally.

3.5.4 Flat Roof Formwork provided for flat concrete roof shall be designed and constructed for the anticipated loads
During the construction of the roof, the formwork shall be frequently inspected for defects. Enough walking platforms shall be provided in the reinforcement area to facilitate safe walking to the concreting area. Loose wires and unprotected rod ends shall be avoided. Formwork supporting cast-in-place reinforced and prestressed concrete floors and roofs shall be adequately tied or braced together to withstand all loads until the new construction has attained the required strengths.
3.5.5 Openings and Holes
Every temporary floor opening shall either have railing of at least 900 mm height, or shall be constantly attended. Every floor hole shall be guarded by either a railing with toeboard, or a hinged cover. Alternatively, the hole may be constantly attended or protected by a removable railing. Every stairway floor opening shall be guarded by a railing at least 900 mm high on the exposed sides except at entrance to stairway. Every ladder way floor opening or platform shall be guarded by a guard railing with toe board except at entrance to opening. Every open sided floor or platform 1.2 m or more above adjacent floor or ground level, shall be guarded by a railing on all open sides, except where there is entrance to ramp, stairway or fixed ladder. Such entrances shall be either guarded with a swinging gate, or so offset that a person is prevented from walking directly into the opening. The railing shall be accompanied by a toeboard at least 200 mm high. The above precautions shall also be taken near the open edges of floors and roofs. Requirements of Sec 1.4.2
and 1.4.3 shall also be met.
3.5.6 Skeleton Construction
Temporary flooring of skeleton construction shall be provided with tightly planked timber over timber supports to withstand all loads. The temporary flooring can also be made of metal sheet supported on timber or tubular steel frame. No end of the timber plank or metal sheet shall remain unsupported. A temporary safety platform or tier shall be maintained within two storeys or 6 m, whichever is less, below and directly under the portion where erection of steel or precast concrete member is required. Tiers shall extend 2.5 m beyond the edge of the work area.

3.6 CONCRETE WORK
3.61 General
All. workmen- involved in-concrete work, shall be-provided- with helmet- and -hand -glove specially-when concrete..pumps,.concrete, …. telements-are.used. Precast piles shall be lifted and driven by skilled workmen under the supervision of a foreman.

Temporary fencing either with bamboo or C.I sheet shall be erected around have equipment delineating the danger zone all centering and shuttering materials shall be kept stacked at site before and after

3.6.2 Prestressed Concrete
Operating, maintenance and replacement instructions of the supplier of the pre-stressing equipment shall be strictly adhered to in all relevant operations. During the jacking of any tension element, the anchor shall be kept turned up close to anchor plate. Thread on bolts and nuts shall be frequently checked for deterioration; choked units shall be cleaned. Hydraulic jacks/rams, pulling-headers and other temporary anchoring devices shall be inspected before use. The
No person shall stand in line with the tensioning elements and jacking equipment during the tensioning operation Also one shall be directly over the jacking equipment when deflection is done workmen shall be prevented from working behind the jacks when the tensioning operation is in progress by putting signs barriers or protective shields.

3.6.3 Concrete Mixers
All gears, chains and rollers of mixer plants shall be guarded. If the mixer has a charging skip, the operator shall ensure that the workmen are at safe distance before the skip is lowered. Barriers shall be provided to prevent walking under the skip while it is being lowered. All cables, clamps,hook wire ropes, gears, clutches, etc. of the mixer shall be checked and serviced once a week. A trial run of the mixer shall be made and defects rectified before using a mixer.

While cleaning inside of the mixing drums, the power shall be shut and fuses removed.
3.6.4 Concrete Truck and Buckets
A reasonably smooth traffic surface shall be provided for concrete trucks. If possible, a loop road shall be provided to allow continuous operation. An easy turnout shall be provided if a loop is not possible to provide. Workmen and moving plants shall not cross the truck line as far as practicable. Concrete buckets conveyed by crane or overhead cableway shall be suspended from deep throated hooks, preferably equipped with swivel and safety latch. Closing and locking of the exit door of the concrete bucket shall always be checked.



3.7 FORMWORK AND SCAFFOLD 3.7.1 Scaffold and Centering Materials
Scaffolds shall be made from strong bamboo poles, -wooden posts steel pipes or any other suitable materials.
They shall be adequately tied to vertical members resting on firm floor. Strong ropes shall be used to tie up bamboo poles. In addition, cross bracing with bamboo or wooden posts shall be provided along with ties or guys of steel wire or rod not less than 6 mm in diameter.
Wooden planks or-steel-sheets shall be placed across-hori2ontaLpoles to provide suitable footrest and carry construction materials. The whole assembly shall be securely lashed together. Deterioration of tying ropes and rotting planks shall be checked from time to time during the construction period and changed if required.
Scaffold shall be dismantled after use piece by piece. Holes in the wall shall be filled up with the same materials as that of the wall. Filled up holes shall have uniformity in texture and colour with the surrounding surface. Crash striking shall not be allowed.
Triangular wooden wedges shall be put under the posts for easy dismantling of the members. Timber planks or steel sheets covering several posts at a time shall be placed below the vertical or inclined posts.
Horizontal and inclined bracings shall be provided for posts higher than 3 metres. Spans of beam bottoms shall be supported by posts at most 1 m apart if steel is used; instructions from the manufacturer/supplier shall be strictly followed. Spacing of props under beams shall consider the increased load, and shall be posted closer than those under the floor slab. All scaffolding exceeding 20 m or six storeys in height, shall be constructed of noncombustible or fire-retardant materials. Centering layout shall be planned by an engineer; bearing capacity of the soil and the effect of weather shall be considered in the planning.
All nails and similar projecting objects shall be removed or hammered down into the timber component of the centering and shuttering materials immediately after stripping off.

3.7.2 Formwork for Concrete The formwork shall be strong and rigidly braced so as not to bulge or sag when concrete is placed. It-shall be constructed in such a way that it can be dismantled without causing damage tothe concerete or disturbing the centering and shuttering of other elements.

Forms shall not be removed until the concrete has developed sufficient strength to support all predicted loads. Workers removing formwork shall wear helmets, gloves, heavy soled safety shoes and belts if adwquate footing is not available above 2m. While cutting any tying wires in tension, care shall be taken against backlash.
Bolts and nuts in vertical concrete walls shall be loosened and withdrawn before initial setting of concrete. The resulting hole shall be filled with rich mortar. The supports shall be dismantled in the order instructed by the engineer. All walls, columns, slabs etc. shall have plastic or mortar spacers (round for vertical structures and flat for slab) to be placed with the reinforcement to provide clear cover as per design. Top layers of slab reinforcement shall be held in position by steel chairs.
The formwork shall be water tight specially for the roof slab. Bamboo matting may be placed on planks or steel sheets to provide a rough surface after stripping of the formwork. Alternatively, ceilings may be roughened up by chiseling immediately after stripping off the formwork.


Suitable camber shall be provided in the formwork for horizontal members. The camber for beams and slabs shall be 1 in 250, and for cantilevers, 1 in 50 of the projected length. Half-seasoned soft-wood, laminated board or other smooth sheet shall be used for formwork for a fair-faced finish. The upper surface of the formwork shall be covered with oiled soft building board or veneered particle board. Oiled paper or polythene sheet shall never be used. The formwork made of materials liable to absorb water shall always be sprinkled with water before laying concrete. Water shall not be profusely used; the formwork shall be in a saturated surface dry condition. All the forms shall be tested both individually and in combination before final use to detect any flaw or defect. Measures shall be taken immediately to remedy any faults, if detected, before the formwork is ready for use. The frame and its joints shall be checked from time to time for the decay in ropes, bamboos, planks etc. The defective parts shall be replaced before the formwork is used.
3.7.3 Load Capacity
Scaffolds, formwork and components thereof shall be capable of supporting without failure, at least two times the maximum intended load. The following loads shall be used in designing the formwork:
a) weight of wet concrete : 20 kN/m3; b) live load due to workmen and impact of ramming or vibrating : 1.5-4.0 kPa
(light duty for carpenter and stone setters, medium duty for bricklayers and plasterers, heavy duty for stone masons);
c) allowable bending stress (flexural tensile stress) in soft timbers : 8,000 kPa.
The sizes for formwork elements specified in Table 7.3.1 are applicable for spans of upto 5 m and height of upto 4 m. In case of longer span and height, formwork and support sizes shall be determined by calculating the load and approved by the engineer before use. All formworks and scaffolds shall be strong, substantial and stable. All centering and props shall be adequately braced to ensure lateral stability against all construction and incidental loads. The space under the scaffold or formwork shall not be used as a working or living space . The space shall not be used as a shelter or refuge during inclement weather or at any other time.

Table 7.3.1 Sizes of Timber and other Sections for Formwork
Table Not available

3.7.4 Bamboos
Good, sound and uniform bamboo shall be collected in sufficient quantities for providing scaffolding, propping, temporary staging, ramp etc. The bamboos shall be free from any defects, firmly tied to eacn other and joints made smooth. Joining members only with nails shall be prohibited. Bamboos for vertical support shall not be less than 75 mm in dia, and shall be straight as far as possible. Bamboos may be used as vertical support for up to a height of 4 metres if horizontal bracings are provided at the centre. Splicing shall be avoided. After stripping the formwork, the bamboo posts shall be cleaned and stacked vertically in shade protected from rain and sun. Defective or damaged bamboo posts shall be removed from the site.

3.7.5 Timber Posts
Timber posts may be used in supporting formwork upto a height of 6 m. The posts shall not be less than 80 mm in diameter at any place and shall spread to at least 150 mm in diameter at the top.


The timber posts shall be supported on timber planks at the bottom. Either the bottom or the top of the posts shall be wedged with a piece of triangular wood peg for easy removal. Adequate horizontal and inclined braces shall be used for all timber centering. All timber posts shall be carefully inspected before use and members with cracks and excessive knots and crookedness shall be discarded. The joints shall normally be made with bolts and nuts. No rusted or spoilt threaded bolts and nuts shall be used.
3.7.6 Steel Centering
Steel centering may be used for any height. In case of patented material, the instructions of the manufacturer regarding the load carrying capacities shall be followed. Post to post supports shall be provided with wooden planks. When tubular steel and timber centering is to be used in combination, necessary precautions shall be taken to avoid any unequal settlement.
Tubular steel centering shall be thoroughly inspected before erection. Defective members shall be discarded and coupling pins aligned to frames. Adjustment screws shall be set to their approximate final adjustment after assembling the basic unit, and the unit shall be level and plumb. The centering frames shall be braced to make a rigid and solid unit. Struts and diagonal braces shall be in proper position and secured. As erection progresses, all connecting devices shall be in place, and fastened for full stability of joints and units.
3.8 ERECTION OPERATIONS
3.8.1 Erection and Hoisting
The erection and striking off, specially of steel structural frame, shall be done by skilled workers. Built-up, swinging and suspended scaffolds shall also be erected by competent workers.

Care shall be taken to keep fire alarms, hydrants, cable tunnels etc. unobstructed during the construction of scaffolding and placement of ladders etc.

Anchors for guys or ties shall be checked for proper placement. The weight of concrete in which the anchors are embedded shall be checked for uplift and sliding. In a tall and heavy guy derrick, tension in guys shall be controlled by hand winches. Enough number of bolts shall be used in connecting each piece using a minimum of two bolts in a pattern to ensure that the joint will not fail. All splice connections in columns, crane girders etc. shall be completely bolted or riveted or welded before erection as specified in the drawings .

The top flange of a truss, girder or long beam shall be temporarily reinforced with a flat bar on top of the member. On deep girders and large trusses, a safety bar running their full length shall be provided. The bar can be a single 16 mm diameter wire rope through vertical stiffeners of each members about one meter above the bottom flange and clamped at tne ends with wire rope clamps. If holes cannot be provided, short eye bolts can be welded to the webs of the girder at intervals. The bolts shall be removed, and the surface chipped to leave it smooth after the erection is completed.

The first load lifted by a guy derrick shall be hanged at a low height for 10 minutes and the anchor inspected for any signs or indications of failure. No load shall be allowed to rest on wire ropes. Ropes in operation shall not be touched. Each truss or deep girder loaded in a vehicle shall be tied back or braced together with other trusses or girders already loaded.

The ropes shall be chemically treated to resist dew and rotting. They shall not be tied on sharp edges of steel structures. They shall not be tied beyond the reach of safety belts complying to BDS 1359.
The proper size, number and spacing of wire rope clamps, depending on the diameter of the wire rope, shall be used. They shall be properly fixed and checked as soon as the rope has been stretched, particularly if new. The clamps shall be promptly tightened when expansion in rope is detected. Clamps and ropes shall be inspected frequently to be sure that they are secured at place.

3.8.2 Small Articles
Adequate supply of bolts, washers, rivets, pins etc. of required sizes shall be maintained at all times. Foot boxes on a guy derrick or climbing crane, shall be moved to the new working floor each time the rig is changed. On a mobile crane, the boxes shall be moved as soon as the crane is moved.
Bolt baskets or similar containers with handles shall be provided on floats or scaffolds where small material, such as bolts and drift pins are used. Small tools shall be gathered up and put away in tool boxes when not in use. Rivet heaters shall have safe containers or buckets for unused hot rivets.

Materials shall not be dumped overboard when a scaffold is to be moved.

3.8.3 Hoist Protection
A material hoist shall not be used to transport workers; temporary elevators shall be installed, if necessary. Proper protection by way of railing, footboard etc. shall be provided to the hoists. Railing shall have a minimum height of l m while the toeboard shall be at least 200 mm high. Where erected on the outside of a building over 20 m or six storeys in height, the hoist structure shall be built of noncombustible or fire retardant materials. Interlocking or any other safety device shall be installed at all stopping points of the hoists. The hoists shaftway shall be fenced in accordance with Sec 3.5.5.
No part of scaffolding or walls and openings shall be hit by crane, truck or heavy moving equipment.
3.8.4 Lifting Gear
Lifting gears shall be of good construction, sound material and adequate strength. Lifting gears must be tested and examined by a competent person. Chains, ropes and lifting tackle shan be thoroughly examined by a competent person every 6 months. Special devices like cleats and hooks shall be used in erecting girders and other heavy structural members. These shall be shop-assembled, bolted, riveted or welded to the piece and left permanently in place after the work. A balance beam shall be used to lift laterally imbalanced pieces. Alternatively, a pair of bridle slings may be used at safe lifting points. Table of safe working loads shall be posted in the tackle store and in prominent positions. No chain, rope or lifting tackle shall be used for loads exceeding the safe working load. Wrought iron gear shall be effectively heat treated.
All lifting gear shall be obtained from reliable manufacturers. No home-made or improvised gear shall be used.
3.8.5 Cranes
All parts of a crane must be of good construction free from defects and properly maintained. Before the crane is used for the first time, it must be thoroughly examined and tested by a competent person. Crane rails, shall be installed and secured on firm ground. In tower cranes, the level difference between the two rails shall remain within the limits prescribed by the manufacturer.
The safe working load shall be clearly shown on the crane; no crane shall be loaded beyond this limit. Nobody shall be allowed to work on the wheeltracks within 6 m of a crane, or under crane where he might be struck, unless effective steps are taken to warn him. Electrical wires within the site which can possibly touch the crane or any member being lifted, shall be removed or made dead. Cranes shall not be operated in proximity to a live overhead power line. If it becomes necessary to operate the crane crossing the safe clearance from power line, the overhead power lines shall be shut off. Cranes shall be thoroughly examined, at least once in 9 months and the results entered in a register. The crane operator shall not violate the safe reach limit of the crane as specified by the manufacturer. Cranes shall not be operated at a speed which causes the boom to swing. No person shall be lifted or transported by the crane on its hook or boom. Toeboards and limit stops shall be provided for wheel barrows on the loading and unloading platforms. Material shall be loaded securely on the platform with no projection. Every crane driver or hoisting machine operator shall be competent to the satisfaction of the engineer and no person under the age of 21 years shall be allowed to operate any hoisting machine and scaffolding winch, or give signals to the operator. The crane driver shall have the full knowledge of controls, signals, loading, misuse, ground and emergency regulations. When the bucket or other members being lifted are out of sight of the crane operator, a signalman shall be posted in clear view of the loading and unloading areas, and the crane operator. Standard hand signals shall be used in controlling the movements of the crane; both the operator and the signalman shall be familiar with the signals.
The crane operator shall respond to signals only from the assigned signalman but shall obey stop signal at any time from any body both inside and outside the site. If a gantry crane is used, a warning bell which sounds automatically during the movement of the crane shall be given to avoid accidents to workmen crossing or standing in the path of the moving loads.
3.8.6 Slings
Chains shall not be joined by bolting or wiring links together. Shortening the chains bv tying knots shall be prohibited. The chain shall be made free of twists and kinks. Proper eye splices shall be used to attach the chain hooks.

Chains with locked or stretched links and which do not move freely shall not be used. Ropes shall move freely in the sheave grooves. Sharp bends in wire ropes shall be avoided; pulley shall be used for these. Idle and loaded slings shall not be carried together on the crane hook. In multi-legged slings, each leg shall be evenly loaded. The slings shall be of sufficient length to avoid wide angle between the legs.
3.8.7 Inspection
Materials and joints in scaffolding shall be inspected from time to time both before and after erection for the soundness, strength, damage due to weathering etc. Inspections shall be made for spillage of material or liquids, loose material lying on the gangways, and proper access to the platform. The scaffold shall be secured to the building at enough places; no ties shall be removed. Warning sign prohibiting the use of any defective or incomplete scaffold and working in bad weather and high wind shall be posted in a prominent place. Inspections shall be made for the observance of these requirements.
3.9 ELECTRIFICATION, EQUIPMENT AND OPERATIONS 3.9.1 Wiring System
All temporary and permanent wiring systems shall be designed by an engineer. All temporary wiring shall be done by an electrician holding relevant licence.
No scaffolding, ladder, working platform, gangway, runway, etc. shall be placed within 3 metres of an uninsulated live electric wire. Overhead wires/cables shall be so laid that clearances as required by Sec 2.2.7 are maintained. Protection shall be provided for all electrical wiring laid on floor which may have to be crossed over. All flexible wiring connecting the electrical appliances shall preferably be enclosed in a flexible metal sheath. Frayed and bare wires shall not be used for any temporary or permanent electrical connection. All electrical circuits, other than those required for illuminating the site at night, shall be switched off daily at the end of the work. The main switchboard shall be located in an easily accessible and prominent place. No clothing or stores shall be kept near it. One 3 kg-4.5 kg CO2 extinguisher, or one 5-kg dry powder extinguisher, shall be provided near the switchboard.

3.9.2 Guarding of Cables
All cables and signal cords shall be guarded wherever such cables and cords pass through or cross working spaces. Location of underground cables, if any, as well as overhead cables, shall be identified and the scaffolds, hoists etc. should be installed after providing proper guards to such cables. Respective agencies shall be consulted for the proper method of providing protection to such cables, distance to be maintained to avoid all hazards etc. Cables, specially underground, and their routes shall be marked for future reference and use.
3.9.3 Lifts
Lifts shall be installed as per instruction of the manufacturer and under proper guidance. If necessary, guards shall be stationed at the installation site. Building materials shall preferably not be carried in a lift. Entry to the empty lift well shall be blocked; the blockade shall be capable of withstanding bumping of an individual against it. Notices/signs shall be displayed in the lift lobby when the lift is not in operation.
3.9.4 Construction Machinery
Construction machinery shall conform to standards specified in the specification of works, or determined as required on site and approved by the engineer. They shall be in running condition without any defect. The machinery shall be operated by competent operators only. The machinery will be checked thoroughly for any defect periodically, as well as each day before use.

Every moving part of or crime mover, and every part of electric generators, motors and rotary converters shall be securely fenced. Fencing shall be of substantial construction, maintained in efficient working order, and kept in position when the machine is in motion.
If machines need to be examined, oiled or adjusted while in motion, it shall be approached by certified mechanics only. Approach to unfenced machinery is allowed only when examination, lubrication etc. cannot be done with machinery at rest, or when machinery cannot be stopped without serious interference with the ongoing process.
Exhaust of petrol or diesel powered air compressors, hoists, derricks, pumps and all such machinery shall be well away from combustible materials. Exhausts opening outside the building shall have a minimum clearance of 200 mm from combustible materials. All sources of ignition like naked flame shall be banned near petroleum- fired equipment.



3.9.5 Heating of Bitumen and Tar
3.9.5.1 Bitumen and Tar Vessels: Tanks, vats, kettles, pots, drums and other vessels for heating tar, bitumen and other bituminous materials shall be made resistant to damage due to transportation, excessive heating etc. All such vessels shall be capable of holding a full load without danger of collapse, bursting or distortion. They shall be provided with a close-fitting cover suitable for smothering a fire in the vessel preventing spillage or protecting the bituminous material from rain.
Buckets for hot bitumen, bituminous material or tar shall have the bail or handle firmly secured, and a second handle near the bottom for tipping. Bitumen or tar boilers shall be mounted on wheels for easy transportation or towing, and provided with hand pumps for spraying purposes. Heated vessels shall not be left unattended. Only vessels using electricity for heating may be used inside buildings. Tar boilers shall never be used on a roof constructed of combustible materials. Bituminous material shall not be thrown into the hot vessels. Vessels shall be kept closed when not in use. Containers shall not be filled to the brim with hot bitumen or tar. Enough space shall be left in vessels for expansion of heated binder.

The vessel shall be leak-proof, and provided with controllable outlets. The buckets and cans in which the hot material is carried shall be checked for any defect before use.

3.9.5.2 Heating of Bitumen and Tar : Gas and oil-fired bitumen and tar kettles or pots shall be equipped with burners, regulators and safety devices. Heating appliances for vessels shall distribute the heat uniformly over the heating surface. If bituminous mixtures have mineral aggregate filler, some means for stirring shall be provided.

Vessels filled with bituminous materials shall be kept at a distance from combustible materials. When vessels are used in confined spaces, the gases, fumes and smoke generated shall be removed by exhaust or forced ventilation.
No naked light shall be used near heated boilers. If a burner stops burning, the fuel supply shall be cut-off immediately and the heating tube shall be thoroughly blown out by the fan.

Cutbacks shall not be heated over an open flame unless a water jacket is used. While they are being heated, the vessel shall be kept open. Blow-lamps or similar devices shall be used for warming pipes instead of burning rags. Bitumen and tar shall not be heated beyond the temperature recommended by the manufacturer of the product.

3.9.5.3 Other Precautions : Indicator gauges shall be used to ascertain level and temperature of the material in the boiler; nobody shall be allowed to peep into the boiler to ascertain the level. In small plants, dipstick may be used to gauge the levels in the boiling pot.
Bitumen and tar shall be kept dry. Boiler shall either have a device that prevents foam from reaching the burners, or anti-foaming agents shall be used to control foaming. The heating shall be at low temperature till the water entrapped, if any, is completely evaporated. Any water present in the boiler shalfalso be drained out before using it. Bitumen or tar spilled around boilers shall be promptly cleaned up. When tanks are cleaned by steam, building-up of pressure shall be prevented. No inspection shall be made while the boiler is under use, or is pressurized.
While discharging heated binder from the boiler, workers shall not stand opposite to the jet. The container shall be handled only after closing the valve. Bitumen and tar shall be handled in a way as not to spill. Mops and other applicators covered with bituminous materials shall not be stored inside buildings. Flame Cutting and Weldin: For all arc welding work, either a helmet or a hand-held face shield conforming to BDS 1360 shall be used.
See also Sec 3.1.2.
All welding and flame-cutting operations shall be performed in protected areas; closed spaces shall be properly ventilated. Suitable protection against the rays of the electric arc shall be provided where arc welding operations might be viewed within normal range by persons other than the welding operators and inspectors. When working on aluminum structures, or close to other welders, protection for the back of the head shall be arranged. When slag is being removed from weld by clipping, the eyes shall be protected by goggles conforming to BDS 1360. Leather gauntlet gloves with canvas or leather cuffs, shall be worn by welders. Any visible foam near the arc shall be rapidly dispersed. Where argon or carbon dioxide is being used as the shielding gas, particularly in confined spaces, breathing apparatus of the airline type shall be worn.

Gas cylinders shall be kept in the upright position, and conveyed in trolleys. While being carried by cranes, the gas cylinders shall be put in cages. The cylinder shall be marked 'full' or 'empty' as the case may be.
Gas cylinders shall be stored away from open flames and other sources of fire. Oxygen cylinders shall not be stored near oil, grease, sources of gas and similar combustible materials.
When the cylinders are in use, cylinder valve key or wrench shall be placed in position. Cylinder valve shall be closed before a cylinder is moved, when the torches are being replaced or welding is stopped for some reason. The cylinder valve and connection shall not be lubricated. A 5 Kg CO; or DCP type fire extinguisher must be kept where gas cutting and welding works are done. Acetylene cylinder which has been subject to heat, must be kept completely submerged in water at least for 12 hours before further use. Gas cutting and welding torches shall be lighted by special lighters, not with matches. The cables from welding equipment shall not be run over by traffic. Double earthing shall be provided to the welding machines. If welding is to be done near combustible materials, suitable blanket shall be provided and fire extinguishers kept nearby. Welding shall not be done in areas where flammable liquids and gases are stored. Gas lines and compressed air lines shall be marked differently by suitable colour codes. Facilities shall be provided in approved closed containers for housing the necessary vision, respiratory and protective equipment required in welding operations.
3.9.7 Riveting Operation
Rivets shall be carefully handled to prevent accidental fall; wooden bottom shall be provided in rivet catchers. Chains shall not be used in riveting dollies; leather, canvas or rope sling may be used.
Snap and plunger shall be prevented from dropping out of place by securing the pneumatic riveting hammer. Nozzle of the hammer shall be inspected from time to time. Torn or worn wire attachment shall be renewed. Water shall be kept ready for putting out fire during riveting operations.

3.10 CONSTRUCTION HAZARDS 3.10.1 General
Implements used for carrying materials to the top of scaffolding shall be of adequate strength and shall not be overloaded during the work. Overhead protection against falling materials shall be provided under scaffoldings and ladders. Care shall be taken in carrying long and heavy bars, rods, angles and other such materials. Precautions shall be taken to correctly handle, use and position precast RC columns, piles, steel beams, joists, angles and other heavy elements. Temporary supports with guys and props shall be provided in Handling heavy elements till the member is properly and permanently secured in position. Manila or Sisal rope shall not be used in rainy season for hoisting heavy materials. People suffering from asthma, chronic bronchitis, pulmonary fibrosis, or pneumoconiosis shall be screened out from being employed in works involving the use of paints, varnishes, plastic foam, rubber, adhesives, etc. Those having impaired lung function, hay fever, eczema, dermatitis etc. shall also be advised to avoid such work. All construction site shall have sufficient general and local ventilation unless otherwise required. Adequate number of Absorptive respirators shall be provided to sites with inhalation hazard. Full breath apparatus shall be used for works of limited period in dangerous situations.
The workers shall be made aware of personal hygiene. Regular health check up shall be arranged for works requiring high physical fitness for prolonged period.
3.10.2 Fire Hazards
Gangways and the ground below the scaffolding shall be kept free from readily combustible materials including waste, debris and any vegetation at all times. Scaffoldings, gangways, etc. shall be constructed with fire resistant materials when blow torch or other equipment producing flame is extensively used near it. A portable dry powder extinguisher of 3 kg capacity shall be kept near all flame producing equipment.
Sec 2.1.2, Sec 2.2.17 and Sec 2.2.18 shall also be followed in addition to the following requirements.

3.10.2.1 Fire Protection: Fire extinguishers, preferably of wa