Examination Category(Building Work)
Textbook for
the Practical Examination

Ver.20220908

Chapter 5: Knowledge of Tools, Machines, Materials, and Measuring Instruments Used on
Construction Sites
5.1 Frame Construction..................................................................................................... 108
5.1.1 Construction Machines .................................................................................... 108
5.1.2 Scaffolding Work ............................................................................................. 110
5.1.3 Steel Framing Work ......................................................................................... 113
5.1.4 Steel Reinforcement Work (Rebar Work) ........................................................ 114
5.1.5 Rebar Splicing Work ........................................................................................ 117
5.1.6 Welding Work .................................................................................................. 119
5.1.7 Formwork Carpentry ........................................................................................ 120
5.1.8 Concrete Pumping Work .................................................................................. 122
5.1.9 Carpentry Work ................................................................................................ 124
5.2 Interior and Exterior Construction .............................................................................. 126
5.2.1 Plastering Work ................................................................................................ 126
5.2.2 Painting Work .................................................................................................. 128
5.2.3 Roofing Work ................................................................................................... 130
5.2.4 Architectural Sheet Metal Work ....................................................................... 131
5.2.5 Tiling Work ...................................................................................................... 132
5.2.6 Interior Finish Work ......................................................................................... 132
5.2.7 Interior Surface Work....................................................................................... 134
5.2.8 Fittings Work.................................................................................................... 135
5.2.9 Sash Setting Work ............................................................................................ 135
5.2.10 Polyurethane Spray Foam Work .................................................................... 135
5.2.11 Waterproofing Work ....................................................................................... 136
5.2.12 Masonry Work................................................................................................ 137
5.3 Common Tools, Machines, Materials, and Measuring Instruments
5.3.1 Power Tools...................................................................................................... 138
5.3.2 Digging/Leveling/Compacting......................................................................... 140

5.3.3 Layout Marking/Marking Tools ....................................................................... 142
5.3.4 Measuring/Inspecting ....................................................................................... 143
5.3.5 Cutting/Bending/Breaking ............................................................................... 145
5.3.6 Tapping/Pulling ................................................................................................ 146
5.3.7 Filing/Polishing/Boring.................................................................................... 147
5.3.8 Tightening/Fixing............................................................................................. 148
5.3.9 Kneading/Mixing ............................................................................................. 149
5.3.10 Curing/Prepping ............................................................................................. 150
5.3.11 Scrubbing ....................................................................................................... 150
5.3.12 Carrying Things ............................................................................................. 151
5.3.13 Hanging/Lifting/Pulling ................................................................................. 152
5.3.14 Work Platforms/Ladders ................................................................................ 154
5.3.15 Cleaning ......................................................................................................... 154

Chapter 6: Knowledge on Construction Site Work
6.1 Matters Common to Construction Sites ...................................................................... 156
6.1.1 Characteristics of Construction Work .............................................................. 156
6.1.2 Construction Plan ............................................................................................. 157
6.1.3 Construction Management ............................................................................... 157
6.1.4 Pre-Construction Preparations ......................................................................... 158
6.1.5 Layout Marking (Marking Out) ....................................................................... 160
6.2 Construction Knowledge of Each Specialty Work ...................................................... 161
6.2.1 Scaffolding Work ............................................................................................. 161
6.2.2 Steel Framing Work ......................................................................................... 163
6.2.3 Steel Reinforcement Work (Rebar Work) ........................................................ 164
6.2.4 Rebar Splicing Work ........................................................................................ 167
6.2.5 Welding Work .................................................................................................. 169
6.2.6 Formwork Carpentry ........................................................................................ 170

6.2.7 Concrete Pumping Work .................................................................................. 171
6.2.8 Painting Work .................................................................................................. 172
6.2.9 Plastering Work ................................................................................................ 174
6.2.10 Carpentry Work .............................................................................................. 175
6.2.11 Roofing Work ................................................................................................. 178
6.2.12 Architectural Sheet Metal Work ..................................................................... 179
6.2.13 Tiling Work .................................................................................................... 181
6.2.14 Interior Finish Work ....................................................................................... 182
6.2.15 Interior Surface Work..................................................................................... 183
6.2.16 Fittings Work.................................................................................................. 184
6.2.17 Sash Setting Work .......................................................................................... 185
6.2.18 Polyurethane Spray Foam Work .................................................................... 186
6.2.19 Waterproofing Work ....................................................................................... 187
6.2.20 Masonry Work................................................................................................ 189
6.2.21 Demolition Work............................................................................................ 190

Chapter 7: Safety during Construction Work
7.1 Fatalities in Construction Work .................................................................................. 192
7 .1 .1 Numbers of Fatalities in Construction ........................................................... 193
7.1.2 Types of Fatal Accidents .................................................................................. 194
7.1.3 Work with A High Number of Fatalities .......................................................... 196
7.2 Safety Activities at Construction Sites ........................................................................ 198
7.2.1 Cycle of Safety in Construction ....................................................................... 198
7.2.2 Safety and Health Education for Newcomers .................................................. 200
7.2.3 Newcomer Education ....................................................................................... 201
7.2.4 Safety Gear for Work ....................................................................................... 202
7.2.5 Prevention of Heat Strokes .............................................................................. 204
7.2.6 Marks Calling Attention to Work Safety .......................................................... 204

7.2.7 Understanding Human Error ............................................................................ 205

Chapter 5: Knowledge of Tools, Machines, Materials, and Measuring
Instruments Used on Construction Sites
This chapter describes the tools, machines, materials, and measuring instruments used in eachconstruction project. Sections 5.1 and 5.2 explain what is specific to each specialty work, by specialty.
5.3 explains what is used in several specialized construction work.

5.1 Frame Construction
5.1.1 Construction Machines[Crane] A machine that can lift a load using power and transport it horizontally. There are several
types of cranes, including tower cranes, truck cranes, and crawler cranes.
[Tower crane] A crane used in the construction of high-rise buildings. The crane section is mounted
on a supporting tower called a mast. There are two types of climbing: mast-climbing (mast climbing
top crane) in which the crane section climbs up a jointed mast, and floor-climbing (internal tower
crane) in which the entire base climbs up the building.
[Rough-ter crane] (rough terrain crane) A type of construction machine with a crane mounted on atruck.
[Crawler crane] A crawler-type crane. It can work in a variety of locations, including on snow andunpaved ground.

Rough terrain crane

Crawler crane108

Tower crane[Tenjo crane] (overhead crane) A type of crane that moves

Overhead cranealong rails attached to the ceiling of a factory or other facilities.
[Yuatsu shovel] (hydraulic excavator (backhoe)) A machinethat performs digging and loading work using the boom, arm,and bucket, which are operated by hydraulic cylinders, and by

Hydraulicexcavator

rotating the upper unit. By changing attachments, it can be used invarious ways as a breaker, a ripper, a crusher, etc.
[Power shovel] A type of hydraulic excavators. A bucket is attached tothe end of the arm. The bucket is mounted with the opening upward.
Suitable for excavating at a level higher than the machine's position.
[Bulldozer] A machine consisting of a crawler (a metal or rubber belt)
type traveling unit equipped with a movable blade (dozer), mainly used
for excavation and transportation. There is also a machine calledrippable (bulldozer ripper) with a ripper that rakes up earth and rock.

Bulldozer[Wheel loader] A loading and carrying machine that run on wheels,with a large bucket in front of the body. By moving the vehicle forward
and operating the bucket and boom, the machine scoops up various
materials such as earth, sand, and quarry stones and loads them onto
dump trucks or other vehicles. A wheel loader is a tractor excavator thatWheel loader

runs on wheels, also called a tire dozer or tire excavator.
[Dump truck] A vehicle used exclusively for transporting earth,sand, rocks, etc., and is capable of unloading soil (dumping) bytilting the bed of the truck. Often used in combination withhydraulic excavators and wheel loaders.

109

Dump truck5.1. 2 Scaffolding Work
[Ashibayo buzai] (scaffolding members) Members used to build scaffolding. The materials used fortube scaffolding, frame scaffolding, and ringlock scaffolding differ from each other.
[Kusabi kinketsushiki ashibayo buzai] (ringlock scaffolding members) Kusabi kinketsushiki
ashiba (ringlock scaffolding) is a type of scaffolding that uses scaffold members designed to beassembled and disassembled with a single hammer. Basic members include jacks, posts, handrails,
scaffold planks with hooks, brackets, cross braces, steel stairs, guardrails, and wall jacks. Basicmembers are galvanized to resist rust and provide durability.
[Wakugumi ashibayo buzai] (frame scaffold members) Wakugumi ashiba (frame scaffold) is a typeof scaffolding in which basic members such as jacks, cross braces, and steel scaffold planks with hooks
are assembled around portal frames. Basic members include formwork, jacks, cross braces, joint pins,
scaffold planks, wall tie anchors, handrails, ledgers, and toe boards.
[Tankan ashibayo buzai] (tube scaffolding members) Tankan ashiba (tube scaffolding) is a type ofscaffolding that is assembled using clamps to bind circular hollow sections made of 48.6 mm-diameter
steel tubes. The scaffold shape can be flexibly changed, allowing it to be used for scaffolding in tightspaces. It is inferior to frame scaffolding in terms of strength and safety, and is mainly used as
scaffolding for painting low-rise exterior walls. Basic members include circular hollow sections, footplates, clamps, circular hollow section brackets, scaffold boards, and joints.
Frame
scaffoldingTubescaffolding

Ringlock scaffolding[Tankan pipe] (circular hollow section) Tubes for scaffolding made of 48.6 mm-diameter steel tubes.
110

[Joint] A member used to connect circular hollow sections.
[Kotei base] (foot plate) Base fitting to fix an upright circular hollow section (tateji (upright circularhollow section)).
[Clamp] Hardware used to connect circular hollow sections orthogonally or diagonally. There are 90degree clamps and adjustable clamps.
[Sujikai] (cross brace) A member used to prevent scaffolding from collapsing due to wind or otherfactors. It is placed diagonally between the posts.
[Ashibaita] (scaffold board) Boards that serve as working aisles and platforms in scaffolding.

Clamp

Cross
brace
Clamp
Circular hollow section

Foot plate

Scaffold board

Foot plate[Nunoita] (scaffold plank with hooks) A member that

Scaffold plank with hooks

serves as the working platform of scaffolding. Unlike
scaffold boards, it has hooks to secure it to the beams
attached to the upright circular hollow section.
[Tankan bracket] (circular hollow section bracket)
A member used to support the scaffold board from below. The horizontal portion onto which thescaffold plank with hooks is supported at an angle.
[Habaki] (toe board) Board material attached to the outer edge of the scaffold board. Attached toprevent objects from falling.

111

Toe board

Circular hollow section
bracket[Kabetsunagi] (wall tie anchor) A member to secure scaffolds to walls and other structures to prevent
them from collapsing.
[Bo’on panel] (soundproofing panel) A panel attached to scaffolding for soundproofing. Aluminumor stainless steel products also serve to prevent the spread of fire.
[Bo’on sheet] (soundproofing sheet) A sheet put up on scaffolding for soundproofing.
[Anzen block] (safety block) A device used to prevent scaffold
workers from falling from heights. The hook of the safety block ishooked to the safety belt.
[Bansen] (thick wire) The thick wire used to assemble scaffolding
is called bansen. To make it stronger than ordinary wire, the iron is

Safety block

treated with heat and then allowed to cool slowly.
[Bansen cutter] (thick wire cutter) A tool used to cut thick wire.

Thick wire cutter

Thick wire

[Chino] A curved tool with a pointed tip. It is used for tying and tightening of thick wires.

112

[Chino tsuki ryoguchi ratchet wrench] (double-ended ratchet wrench with chino) One end of thegrip is pointed, allowing tightening of thick wires, etc. The pointed end is called shino (chino). The
other end with a hole allows tightening and loosening of bolts. It is used in scaffolding and rebar
construction. The size mainly used by steeplejacks is 17 x 21 mm.

Chino

Ratchet wrench with chino[Ratchet wrench] A wrench that incorporates aclutch that fixes the direction of rotation in one
direction (called ratchet kiko (ratchet mechanism)).
The ratchet mechanism allows efficient turning of bolts
and nuts using only the back and forth motion of the

Ratchet wrench with chinolever. In steel framing work, a ratchet wrench with achino, or a pointed form, on one end, is used.

5.1.3 Steel Framing Work
[Borushin] (drift pin) A tool used to align bolt holes in steel section joints by tapping into the bolt
holes when they are misaligned.
[Wrench, spanner] A tool used to tighten and loosen bolts
and nuts by rotating them. In American English, it is called
wrench, and in British English, spanner. They both mean thesame thing in English, but in Japan, they refer to different
tools. The wrench has a hexagonal tip and captures the bolt at
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Spanner

six points, while the spanner has an open tip and captures the bolt at two points.
[Megane wrench] (box wrench) A wrench with ends of different diameters on both sides of the grip.
[Combination wrench] A wrench that has an opening and captures and turns bolts and nuts at two
points. A combination wrench is a wrench with one spanner end and one box wrench end. The end isangled at 15 degrees to the grip, so the back and front sides can be used alternately to provide a rotating
stroke for efficient work.
[Impact wrench] A power tool for turning and tightening hexagonal bolts using the impact from thebuilt-in hammer.

5.1.4 Steel Reinforcement Work (Rebar Work)[Tekkin cutter] (rebar cutter) A tool used to cut reinforcing steel bars. There are four types: manual,
manual hydraulic, electric hydraulic, and electric circular saw with a tipped blade.
[Dendo tekkin cutter] (electric rebar cutter) A power toolthat uses a hydraulic pump to move the blade and cut the rebar.
The rebar is grasped with the tip, and cut by pressing the blade
against it.
Electric rebar cutter[Dendo yuatsushiki tekkin cutter] (electric hydraulic rebar
cutter) A portable cutting machine that can cut rebar using electricity and hydraulic pressure.
[Tekkin bender] (rebar bender) A tool used to bend rebar.
[Dendo yuatsushiki tekkin mageki] (electric hydraulic rebar bender) A portable bender that canbend rebar using electricity and hydraulic pressure.

114

[Teichishiki tekkin mageki] (stationary rebar bender) Stationary-type rebar bender mainly used inrebar processing plants.

Rebar bender

Stationary rebar bender[Tekkin kessokuki] (rebar tier) A power tool for tying
rebars. Simply insert the arm into where the rebars cross, andpull the trigger to tie them.
[Spacer] A member to secure space (space between the rebar andthe formwork) of the rebar. Spacers for the sides are called
donuts, and the members that hold the top and bottom of the slab

Rebar tieror beam are called bar supports.
[Donut] Donut-shaped spacers fitted to rebars to secure space for the correct concrete cover thickness
in columns, beams, and walls.
[Caramel] Dice-shaped mortar blocks placed under the floor rebars to secure space for the correct
concrete cover thickness of the floor.
CaramelDonuts115

[Pura cap] (plastic cap)

Plastic cap

Plastic caps placed conspicuously over the tops of the verticaljoint bars and the edges of horizontal bars after completion of therebar placement as a safety measure to prevent injury.
[Orijaku] (folding ruler) A tool for measuring short lengths. It
is mainly made of fiberglass or wooden material and has anextended length of one meter. It is useful when working alone orin situations where it is difficult to work because it can be folded.
Folding
rulerThis tool is often used in rebar work.

[Kessokusen] (binding wire) A mild steel wire (generally No. 21 in thickness) used to connect rebars.
[Hacker] Rebars are tied together to secure them. The tool used to twist and tighten the binding wire
used for tying rebars is called a hacker. It is the most important tool for a rebar worker. There is ahacker case to store the hacker.

Binding wire

Hacker[Nifuda/efu] (tag) A tag indicating the size, use, position of use,and number of rebar brought in to the site. It is tied to the rebar
using a thin wire.

116

5.1.5 Rebar Splicing Work
Ram cylinder[Kaatsuki] (pressure system) The section consisting of ahydraulic power unit, a high-pressure hose, and a ram cylinder,
which generates the hydraulic pressure necessary for pressure

Welding
fixturewelding.
[Assetsuki] (welding fixture) The section in which two rebars to bepressure-welded are set. It is driven by hydraulic pressure generated by apressurizing pump.
[Ram cylinder] A device used to transfer the hydraulic pressure to thepressure system.
[Koatsu hose] (high-pressure hose) A hose with a flexible bendable

Electric pressurizer

structure that can withstand high pressure.
[Dendoshiki kaatsusochi] (electric pressurizer) A hydraulic pump that can set the pressurizing
power as desired. Pressurization can be turned on and off with a switch at hand.
[Jido kaatsusochi] (automatic pressurizer) A machine in which pressurization sequences areprogrammed to automate pressurization.
[Burner] (welding torch) The section that emits flames to heat the pressure-weld joint. There areseveral different shapes.
[Suikan] (blowpipe] A heating apparatus for mixing and delivering oxygen and acetylene gas.
[Eco-valve] A valve designed to open and close the oxygen and the acetylene gas flow at the sametime. It is used by attaching it to a blowpipe.

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Blowpipe

Eco-valve

Burner[Gaikan sokuteiyo kigu] (welding gauge) An inspection tool
to measure the diameter and width of the bulge of the pressureweld joint.
[Cho’onpa tanshoki] (ultrasonic flaw detector) An
Welding gauge

inspection device that detects internal defects by applying
ultrasonic waves to the pressure-weld joint.

[Hippari shikenki] (tensile tester) A machine that performs tensile tests, which pulls pressure-welded
rebars, to test the strength.
[Mage shikenki] (bend tester) A machine that performs bend tests totest the strength of pressure-welded rebars.
[PS ring] A high molecular weight reducing agent to prevent oxidationof pressure-weld joints. It also makes it less susceptible to wind and rain.

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PS ring

5.1.6 Welding Work
[Hifuku arc yosetsuki] (shielded arc welding machine) A
welding machine that uses a welding rod with a metal core
covered with a coating material (called “flux”). This type of
welding machine is often used at work sites. Welding with ashielded arc welding machine is sometimes called teyosetsu

Shielded arc welding machine(manual welding) because it is done entirely by hand.
[Yosetsubo] (welding rod) Metal rods used to bond the base metal to be welded. In arc and gas
welding, it melts and becomes one with the base metal.
[Yattoko] (pliers) A tool made of iron for gripping heated iron and other materials. It consists of two
metal rods connected by a hinge. They can be used to grasp objects with strong force using theprinciple of leverage. They are also used in welding to bend things.

Welding rod
Pliers[Sekihitsu] (stone scribe) A tool used to draw kegaki (scribe marks) on iron plates, etc. for welding
and torch-cutting. Kegaki (scribe marks) means to scratch and draw lines on the material.
[Spatter fuchaku boshizai] (anti-spatter compound) Spatter is the slag and metal particles scatteredduring welding. Since they can lower the quality of the weld
finish, this compound is used to prevent the spatter fromsticking. The compound is applied to the material before welding
by brush or spray.
[Shield-mentsuki helmet] (welding helmet) A helmet with a
119

Helmet with a face shieldshield attached to it, protecting the entire face. Mainly used for welding work.

5.1.7 Formwork Carpentry[Form tie] A tool attached to separators toForm tiekeep the formwork spacing constant,
improve passage, and prevent deformationof the formwork due to lateral pressure

Concrete wall
Round separator

from the concrete. It is used to bind the

P-con

tubes.
[Maru separator] (round separator) A

Circular hollow
sectionFormwork
plywoodtool commonly called sepa or marusepa
that is placed between formwork facing each other to ensure that the thickness of the concrete will be
as indicated in the construction drawings.
[P-con] A plastic part that is attached to an end of aseparator. Attached to both ends of the separator, they hold

Circular hollow
sectionthe formwork panel in place.
[Tankan pipe/kokan pipe] (circular hollow section,
Form tiesteel tube) A material used to increase the strength of theformwork. Circular hollow sections are round whereas steel tubes are square-shaped.
[Sangi] (batten) A 25 x 50 mm piece of wood used together with plywood. It is used at joints between
panels and to supplement the strength of the formwork.

120[Sekiita] (formwork plywood) Plywood used to make formwork. Generally, 12 mm thick conpane(formwork plywood) is used.
[Panel katawaku] (panel formwork) A panel-shaped
formwork made by nailing pieces of batten onto plywood
to create a panel. Panel formwork is intended for repeatedPanel formworkuse.
[Batakaku] (floor support timber) Square timber with a width of 90 mm or 105 mm. It is used toerect tube supports and to support the circular hollow sections for the floor framework. It is also used
as a platform on which to place heavy objects.
[Pipe support] (tube support) A member used for the bottom plate of beams and as supports for floor
formwork. It bears the compressive forces. It is called sapo, sappo, support, etc. for short.
[Tonbo bata] (beam support timber) Square timber often referred to as tonbo and used to constructpipe supports for receiving the circular hollow section (called neda pipe (joist tube)) for the beambottom formwork.

Floor support

Beam bottom

timberformwork

Tube support
Tube support

Beam support
timber[Kakikomizai] (grooving material) A material attached to the formwork to make grooves in concrete
for window frames, etc. It is commonly referred to as ankozai.
[Mengi] (cornering material) Material used to create corners with concrete.
[Mejibo] (grooving rods) Material used to make grooves in the flat surface of concrete.
[Turnbuckle/chain] Used to prevent collapsing of the formwork and to adjust the verticality (i.e., to121

accurately level and straighten the columns and beams) by pulling.
[Separator hook] A tool used to guide the separator into the hole drilled in the formwork.

Chain

Turnbuckle

Separator hook

[Form tie mawashi] (form tie spanner) A tool used for tightening and loosening form ties.
[Kariwaku hammer] (formwork hammer) This hammer is used to make the formwork for pouringconcrete. It can also pull out nails.
Formwork hammer

Form tie spanner[Hakurizai] (release agent) An agent applied to the surface of the formwork to facilitate removal.

5.1.8 Concrete Pumping Work
[Agitator] A device that agitates pre-mixed concrete to prevent it from hardening. Trucks equippedwith this function are called truck agitator (concrete agitator trucks) or nama-consha (ready-mixed
concrete trucks).
[Concrete pump] A machine that uses hydraulic or mechanical pressure to feed ready-mixed concrete(concrete made at a factory that has not hardened yet) brought in by concrete agitator trucks into the122formwork. There are two types of pumps: piston shiki (piston type), which has high pressure and canpump over long distances, and squeeze shiki (squeeze type), which has low pressure and limited
pumping distance. A device in which a concrete pump is mounted on a vehicle is called a concrete
pump truck.
[Hopper] (concrete hopper) A part that receives ready-mixed concrete from a concrete agitator truck.
A screen is attached to the concrete hopper to prevent people and foreign objects from falling into thehopper.
[Level sensor sochi] (level sensor device] A device that detects the amount of concrete in the hopperand automatically operates and stops the machine.
[Kinkyu teishi sochi( (emergency stop device) A device used to stop the movement of the concrete
pump when a person is about to be or is caught in the agitator.
[Agitator jido teishi sochi] (automatic agitator stop device) A device that automatically stops the
movement of the agitator when the hopper screen is opened.
[Doryoku dentatsu sochi (PTO)] (Power Take-Off (PTO)) A device used to take the power fromthe engine needed by various parts of the concrete pump. Engine power is transmitted to drive theconcrete pump truck, operate the outriggers and boom, and power the hydraulic generator.
[Yuatsu kairo] (hydraulic circuit) A device that generates the hydraulic pressure to move theequipment of the concrete pump truck. The hydraulic circuit consists of a hydraulic power unit, ahydraulic control unit, a hydraulic actuation system, and other ancillary equipment.
[Jido kyuyu sochi] (automatic lubricator) A device that sends grease from a grease pump to thebearings of concrete cylinders, S-pipes, and agitators.
[Senjo sochi] (washer) A device used to wash concrete left in various parts of the equipment of
concrete pump trucks after pumping operation.
[Boom sochi] (boom) Equipment used to bring the delivery pipe to the location where the concrete is
to be placed. Booms can be folding, telescopic, or a combination of these types.
123[Senkai sochi] (boom manipulator) A device that moves the boom up and down and swivels it.
[Kadai sochi] (superstructure) A structure for attaching boom and outrigger devices to the vehicle
body. It consists of a sub-frame and a boom pedestal.
[Outrigger sochi] (outrigger) A device that extends outward from the body of the vehicle to maintainthe stability of the concrete pump truck.
[Yusokan] (delivery pipe) A pipe used to deliver concrete from the concrete pump truck to thelocation where the concrete is to be placed. It consists of straight pipes, elbow pipes, tapered pipes, aplacing hose, etc.
[Cement] Material used to make concrete. It has the property to harden when mixed with water.
[Kotsuzai] (aggregate) Sand or gravel that is mixed with cement when making concrete or mortar.
[Konwazai] (mixing agent) Anything other than cement, water, sand, and gravel that is added toconcrete to improve its performance. Includes damping agent, superplasticizer, and hardening
accelerator.
[Slump cone] A formwork for conducting a slump shiken (slump test) to check the quality of readymixed concrete. After pouring the ready-mixed concrete into the slump cone, the slump cone isremoved in order to check the change in height of the ready-mixed concrete. A slump test is always
performed prior to placing concrete.

5.1.9 Carpentry Work
[Tenoko] (hand saw) A saw, also called hand saw, that cuts byHand saw

hand. Some can be folded.
[Tatebiki nokogiri] (rip saw) A saw used to cut along the grainof the wood. On the other hand, a saw used to cut across the grain
is called yokobiki nokogiri (crosscut saw). Rip saw and crosscut saw have differently shaped teeth.

124

[Ryoba nokogiri] (double-edged saw) A saw with teeth on both sides. One side is tatebiki (rip saw),
and the other is yokobiki (crosscut saw). Both of these cut on the pull.

Double-edged saw

Crosscut saw

Rip saw[Dotsuki nokogiri] (backsaw) The opposite side of the blade isBacksaw

reinforced with metal. The blade does not shake while cutting,allowing for a clean cut.

[Genno] (Japanese hammer) A woodworking hammer used forhammering nails and hitting wood chisels. It is slightly bulged toGennoallow the nail head to sink into the wood at the end of the nailingprocess.

[Nomi] (wood chisel) A tool used for carving trenches or holes
in wood. The type with a metal ring attached to the butt of thehandle so that it can be struck with a hammer is often used. To
maintain sharpness, it is necessary to sharpen the blade with awhetstone.

125

Wood chisel

[Kanna] (hand plane) A tool used to shave and smooth theJapanese hand planesurface of wood. The blade is attached to a wooden base. To
maintain sharpness, it is necessary to sharpen the blade with awhetstone.

[Kiri] (Japanese awl) A tool used to make holes in wood byrotating the blade. The handle is held between the palms of theJapanese awl

hands, and the hands are moved to rotate the handle to make ahole. The shape of the tip of the blade differs depending on the
purpose. Typical examples include yotsumegiri, mitsumegiri,tsubogiri, and nezumihakiri.
Marking gauge[Sujikebiki] (marking gauge) A carpenter's tool used to easily
mark accurate lines parallel to the reference.

5.2 Interior and Exterior Construction
5.2.1 Plastering Work
[Mortar] A building material made by mixing cement with water and sand. Unlike concrete, it does
not contain gravel. It is used for walls and floors of houses and as an adhesive for stacking bricks andblocks.
[Shikkui] (Japanese plaster) Slaked lime is the main ingredient in this coating material. It is madeby kneading slaked lime with glue and susa (a plant fiber binding material). Because it is water
absorbent and removes moisture, it has long been used as a coating material for the interior walls of126

warehouses. It is also airtight.
[Kote] (trowel) A tool used to apply Japanese plaster or concrete to walls, floors, etc. There are many
types, depending on usage. Plasterers use dozens of kote . Materials include iron, stainless steel, plastic,
rubber, and wood. Each type has its own name, and when referring to it, for example, shiage gote(finishing trowel) meji gote (joint trowel), the term kote is modified as gote.
[Shiage gote/nakanuri gote] (finishing trowel/middle coat trowel) The trowel tip is pointed. Used
for wall coating with Japanese plaster, diatomaceous earth, mortar, etc. A middle-coat trowel is usedfrom the middle coat to rough finishing.
[Yanagiba gote] (willow leaf trowel) The shank is attached to the base of the handle and the heel ofthe blade. Suitable for working on small parts.
[Meji gote] (joint trowel) Used for finishing decorative joints of tiles, bricks, and blocks. It has anarrow width to match the joints.

Joint trowel

Willow leaf trowel

Middle-coat trowel[Kaku gote] (rectangular trowel) The blade is rectangular and heavy. It is mainly used for osae(press) finishing.
[Renga gote] (brick trowel)

A trowel used for stacking bricks. Shapes are momo-gata (peach-shaped) and fuku-gata (wider-shaped), and some sizes are used for tiling as well.
[Block gote] (block trowel) A trowel used for stacking concrete blocks. The tapered end makes it easy
to pour mortar into the hole in the block.

127

[Menbiki gote] (outside corner trowel) Used to finish theOutsidecorneroutside corner.

Insidecorner[Kiritsuke gote] (inside corner trowel) Used to finish theinside corner.

Outside corner
trowelInside corner
trowel[Kushime gote] (notched trowel) A part of the blade is notched like a comb. Used to apply adhesiveor mortar in tile installation. It is also used to add patterns to diatomaceous earth walls.
[Koteita] (trowel board) A platform on which plastering materials and mortar are placed. It is held in
one hand while working.
[Chiriboki] (dusting brush) A tool used in plastering work to clean up the chirigiwa (the area where
the pillar meets the wall).

5.2.2 Painting Work[Hake] (brush) A tool for painting with bristles attached to the end of a wooden or plastic handle.
There are various types of brushes, including bristle brush, rubber brush and flat brush, depending on
the area to be painted and the type of paint, such as oil-based or

Brushwater-based.
[Pate] (putty) A paste-like material used to eliminate
unevenness and flatten the surface of a substrate (called pateshori (puttying)).
[Hera] (spatula) This tool can be used to mix, apply, and scrape off paint.

128

[Jushibera] (resin spatula) Used for mixing putty, filling putty,

Resin spatulaspreading adhesives, and pressure bonding masking tapes. There aredifferent types depending on the hardness (bendability), and they areused for different purposes.
[Kanabera] (metal spatula) Used for various purposes such as
mixing putty, leveling and finishing, and pressing sealant.
[Joban] (mortar board) A thin board to be held with one hand on which mortar or putty is placed.
Mortar or putty is kneaded using a spatula on the mortar board.
[Teguwa] (plasterer hoe) A tool used to mix wall materials and carry them to the place where they
are to be painted. It is sized so that it can be held and operated with one hand.
[Wool roller] A roller used for efficient painting of wide
Wool roller

surfaces. Used in combination with roller handles. Longer
bristles allow the paint to soak in better and are suitable forpainting large surfaces. The shorter ones leave less hair trails
and create a cleaner finish. There are also polyurethane rollers
which can be used for water-based and solvent-based paints.

Blade of a scraper[Scraper] A tool used to remove stuck-on paint and dirt. The
process of scraping off rust and other debris from surfaces
before painting is called keren sagyo (scraping work), and ascraper is used in this process. Larger ones, also called kerenbo
Skiving knife(scraping sticks), are used not only for the scraping work but
also for removing P-tiles from the floor.
[Kawasuki] (skiving knife) The tool was originally used toskive skins, but because of its sharp blade, it is also used for
keren sagyo (scraping work) in the painting process.
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[Spray gun] A painting tool that uses compressed air from a compressor to spray a fine mist of paint.
Depending on the paint supply method, there are gravity, suction, and pressure-feeding types.
[Masking tape] A tape used to protect certain areas from paint. It is applied to the border between thepainted area and the area to be protected. It can be easily peeled off. To prevent paint from seeping inthrough the gaps, press the tape down well with finger so that there are no lifted areas.
[Masker] (masker tape) Adhesive tape with a folded sheet to easily protect a large area. The tape isapplied to the protective surface first, and then the sheet is unfolded. Non-slip type is also available.
[Tape primer] A primer used for areas where masking tape is difficult to adhere, such as uneven areasof concrete. Spray-type products are often used.

Masking tapeProtective tape

Masker tape

Tape primer

5.2.3 Roofing[Kawarayo hammer] (roof tile hammers) A hammer used not only for hammering nails but also forprocessing roof tiles. The surface used to hammer nails is square to make it easier to split roof tiles.
The other side is pointed.
[Kawara gote] (roof tile trowel) A trowel used for heaping up thatching soil and (nanban) plaster.
[Mendo gote] (roof-pointing trowel) A trowel used to apply Japanese plaster to the space (called
mendo) between noshigawara (tiles on the roof ridge) and shikigawara (roof tiles).
[Tsurukubi] (crane neck) The shank of this trowel is longer than that of the roof-pointing trowel, likethe neck of a crane. Used for plastering work.
[Kawara cutter] (roof tile cutter) A tool used to break tiles by push cutting them and processing
130them into the required shapes.
[Niageyo winch] (hoisting winch) A machine used to hoist roofing tiles and other roofing materials
up to the roof.

5.2.4 Architectural Sheet Metal Work
[Kananoko] (hacksaw) This saw can cut metal, plastic,

Hacksaw

plasterboard, bricks, etc. The blade is selected according to thematerial to be cut. A wood saw cuts on the pull, but a hacksaw
cuts on the push.
Willow blades[Bankin basami] (sheet metal scissors) Scissors for cutting
thin steel sheets. There are several blade tip shapes available,
depending on the application, such as straight blades for easy
cutting of straight lines and willow blades for easy cutting ofStraight blades

curved lines.
[Yoyu aen mekki kohan] (hot-dip galvanized steel sheet) A galvanized steel sheet widely used forduct work. Also called aen mekki teppan.
[Toso yoyu aen mekki kohan] (coated hot-dip galvanized steel sheet) Hot-dip galvanized steel sheetcoated with synthetic resin paint and baked. Also called chakushoku aen teppan or color teppan.
[Stainless kohan] (stainless steel sheet) An alloy steel of iron that contains chromium (11% or more).
A thin protective film is formed on the surface, making it resistant to rust and able to maintain its
beauty. It is used in kitchens and other places where humidity is high and cleanliness is required.

131

5.2.5 Tiling Work[Dashinbo] (tapping rod) A tool used to check for peelingtiles and floating mortar. The sound produced when thesurface of the tile or mortar is tapped is listened to identify
the location of the floating. There is also a type of tapping

Tapping rod

rod that is used by rolling a metal ball attached to the endof the stick.
[Tatakiita] (tile setter) A tool for applying mosaic tiles coated with mortar onto the surface by tapping.
[Shindo kogu] (vibration tool) A power tool used to improve adhesion of tiles. The tiles are set byvibrating the tiles and kneading in the mortar.
[Tile cutter] A pencil-shaped tool used to cut thin tiles. Tiles are cut by scratching the surface andbreaking along the scratch. Tile cutters are used to scratch the surface and break the tile by tapping theback of the tile. For cutting thick tiles, tile setsudanki (tile cutting machine) is used. The tile cutting
machine scratches the surface of tiles by pulling down the lever while pushing the tile forward, andby applying more force to the lever, it breaks the tiles along the scratches.

5.2.6 Interior Finish Work[Sekko board] (plaster board) A construction board
material made of gypsum plaster core wrapped withbase paper for boards. It is mainly used as a basematerial for walls. It can be easily cut by grooving it

Plaster board

with a cutter and then folding it.
[Board yasuri] (plastering rasp) A tool used to smooth the cut edges of cut plasterboard.
[Board mentori kanna] (plasterboard chamfer plane) A plane used for chamfering (smoothing132

corners) of plasterboard.
Plastering rasp

Plasterboard chamfering plane[Stud] Upright columns for partition walls in steelStudstud framing. It is inserted into the upper and lower
Spacerrunners for installation.
[Spacer] A fitting that is attached to a stud to preventBrace

the stud from being crushed.
[Furedome] (brace) A member that suppresses thestuds from swaying in the wall plane direction.
Suspension bolt

[Tsuri bolt] (suspension bolt) A fitting forsuspending the ceiling base.
HangerCeiling joist[Hanger] Attached to the suspension bolt, thisfitting is used to hang the ceiling joist support.
Ceiling joist support[Nobuchi] (ceiling joist) A member for attaching aceiling base or a finishing board for a ceiling. A wide ceiling joist is
Runnercalled double nobuchi.
[Nobuchiuke] (ceiling joist support) A member used to secure theceiling joist.
[Nobuchiuke joint] (ceiling joist support joint) A fitting to connect
two ceiling joist supports.

Runner[Clip] A fitting used to secure the ceiling joist to the ceiling joist
133support.
[Runner] In steel stud framing, this rail is used to erect upright studs as a base for partition walls. The
lower side is fixed on the floor slab and the upper side is mounted under the beam or under the slab.
[Joint tape] Tape used to smooth the joints of the plasterboards. Fiber tape and other tapes are used.

5.2.7 Interior Surface Work
[Senmai toshi] (eyeleteer) Also called hoshitsuki. A tool used

Eyeleteer

to make holes in soft objects such as cloth and paper. It canalso be used to mark out dimensions or to crease wallpaper,
etc.
[Compass] A tool used to draw circles and arcs, and to transfer
the same length to another part or material. It has two legs, onewith a needle and the other with a pencil or mechanical pencil.
[Divider] Similar to a compass, but has needles on both legs.
It is used for the purpose of transferring the same length toanother part or material.

Divider
Welding
machine[Yosetsuki] (welding machine) A tool used to treat the joints
between vinyl floor sheets or vinyl tiles. The welding rod is
Weldingrod

melted and integrated with the joint.
[Yukazai acchakuyo roller] (roller for pressure bonding
flooring material) A roller used to firmly bond flooringmaterial to the substrate using pressure. It is constructed insuch a way that it can pressure bond by the weight of theRoller for pressure bonding
flooring material

worker.

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[Cross roller] A roller used to pressure bond the wallpaper onto the substrate.
[Osae hake] (wall brush) A brush is used to push air out of the wallpaper and to stretch out wrinkles.

Cross roller

Wall brush

5.2.8 Fittings WorkIn fittings work, almost the same tools are used as in carpentry work. Also, a screwdriver is used tosecure the door to the frame.

5.2.9 Sash Setting Work
[Kusabi] (wedge) Made of hard wood, metal, or rubber, it is thick on one side and thin on the other.
Inserting the thin part into a gap and striking it can split wood and other materials. It is also used for
positioning when installing sash frames.

5.2.10 Polyurethane Spray Foam Insulation Work
[Dannetsuzai] (insulation) Materials used to block or retain heat.
[Koshitsu urethane foam dannetsuzai] (rigid polyurethane foam insulation) Insulation made byfoaming polyurethane into a hard sponge-like state. It has excellent insulation properties because it
has trapped gases that do not conduct heat easily.
[Koshitsu urethane foam gen’eki] (rigid polyurethane foam liquid) Rigid polyurethane foam is135made from polyisocyanate and polyol components. Mixing and stirring the two liquids causes achemical reaction that simultaneously forms polyurethane and foams to create rigid polyurethane foam.

5.2.11 Waterproofing Work
[Torch burner] (blow torch) A tool used in the torch method of asphalt waterproofing. The asphalt
waterproofing membrane is attached to the substrate by melting it with a blow torch at a temperatureof over 1000°C. It is used by connecting a propane gas hose from a propane gas tank.
[Sealing gun] A tool used to inject sealant in a cartridge into the
Caulking gun

work area. Sometimes called a caulking gun.
[Tacker] A large stapler-like tool. It is used to fix waterproof
sheets, heat insulating materials, and finishing touches forinterior materials. Types of tackers include gun tackers, hammer
Gun tacker

tackers, electric tackers, and air tackers.
[Primer] Material applied to the substrate to improve theTacks

adhesion of the waterproof layer to the substrate.
[Asphalt roofing] A waterproofing membrane made by soaking
asphalt into the base paper made mainly from natural organic fibers. It has the property of softening
at higher temperatures and hardening at lower temperatures. In locations where there is a large
temperature difference between summer and winter, it will deteriorate over the years, causing cracks
and fissures, resulting in loss of its waterproofing property.
[Kaishitsu asphalt roofing] (modified asphalt roofing) A waterproofing membrane made by mixing
asphalt with rubber, synthetic resins, polymers, plastics, etc. to increase durability in order to reduce
deterioration caused by temperature changes, which is a disadvantage of asphalt.
[Karyu gomukei sheet] (vulcanized rubber sheet) A waterproofing membrane made from136

vulcanized rubber (rubber with the property of expanding and contracting).
[Enbi sheet] (PVC sheet) A waterproofing membrane made of polyvinyl chloride resin. It has
excellent resistance to ultraviolet rays, heat, and ozone from sunlight.

5.2.12 Masonry Work
[Block hammer] (brick hammer) A hammer used to break concrete, brick, stone, etc. One side is flatfor striking, and the other side is tapered flat and pointed for easy scraping and cutting.
[Koyasuke] (chisel with a perpendicular handle) A type of nomi (chisel) used to break stones. One
side of the head is a blade. The opposite side of the blade is struck by setto (iron mallet) to break stones.
[Setto] (iron mallet) A small iron mallet.
[Bishan] (bush hammer) An iron mallet used to tap thesurface of stone that has been carved with a masonrychisel or other tools to smooth it out. The tapping surface
has fine protrusions. At first, hammers with larger

Iron mallet

protrusions are used to tap the surface, and then gradualswitching to hammers with finer protrusions finishes the surface.
[Kanajime] (garden hammer with a metal ring) It is in the shape of a hammer, but has an iron ringattached to the butt of the handle.

1375.3 Common Tools, Machines, Materials, and Measuring Instruments
5.3.1 Power Tools
Power tools can be cordless types that use rechargeable batteries or corded types that use AC power.
[Drill driver] This electric screwdriver can be used for screwing and drilling by changing the bits.
Rotation speed and torque can be adjusted.
[Impact driver] An electric screwdriver that can tighten screws using the impact from the built-in
hammer. It has more power than a drill driver. Rotates at a constant rotation speed and torque.

Drill driver

Impact driver[Bit] A part attached to the tip of an electric screwdriver. Various types of bits for drilling and screws
are available. The part where the bit is attached differs between a drill driver and an impact driver.
Drill driver

Impact driver[Disk grinder] (angle grinder) This power tool can cut, grind, and remove paint from metal pipes
and concrete by changing the disc (a round, flat grinding stone for grinding and cutting) attached tothe end of the tool. The high speed torque type is suitable for metal cutting, while the low speed torquetype is suitable for grinding.

138

Angle grinder

Disk[Sander] This power tool is used to polish flat surfaces by moving sandpaper. There are several typesof mechanisms for moving sandpaper, including vibrating, belt, and rotating types.
[Marunoko] (circular saw) A power tool for cutting plywood and other materials in a straight line.
Hand-held and fixed types are available. The hand-held type, when it touches the material to be cut,
may move in an unexpected direction due to a force (called kickback) that lifts it away from thematerial. This leads to many accidents, and in some cases, they can be serious, life-threatening
accidents. Before use, make sure that the safety cover is working properly.
[Marunoko guide jogi] (circular saw guide ruler) Attached to a circular saw, this ruler is used to cut
materials in a straight line.
Circularsaw

Circular saw guide ruler[Shujin marunoko] (circular saw with dust collection) A circular saw that can cut while collecting
fine dust. Two types are available: one for board cutting and the other for metal cutting. There are two
types: one with a dust box to collect dust, and the other with a dust collector to be connected to thecircular saw.
139

[Shujinki] (dust collector) A power tool used to collect dust produced by cutting. It is used whencutting tile and concrete products to prevent cutting debris from flying out into the neighborhood.
[Kosoku setsudanki] (high-speed cutter) An electric toolthat cuts metal pipes, rebar, light steel sections, etc. byrotating a grinding stone for cutting. Much like a chip saw
cutter, but a chip saw uses a circular saw blade to cut
High-speed cuttermaterials. Whereas the blades of chip saw cutters are prone
to wear, the blades of high-speed cutters are characterized
by their longevity.
[Recipro saw] (reciprocating saw) A power tool that cuts
materials by moving a long, thin blade back and forth.
Nail gun[Dendo block cutter] (electric block cutter) A power tool for
cutting concrete.
[Kugiuchiki] (nail gun) A tool that uses the force of air pressurecompressed by a compressor to drive nails into materials. A
compressor is a machine that compresses air.
[Denko drum] (cord reel) A tool for extending an outlet.

Cord reel

5.3.2 Digging/Leveling/Compacting[Ken sukoppu] (spear head spade) A tool used for digging in the ground by placing the foot on the
top of the head. It is also called kensuko for short. Do not use as teko (lever).
[Kaku sukoppu] (square head spade) A tool used to scoop and carry soil, asphalt, etc. It is similar
to a spear head spade, but the blade edge is straight to make it easier to scoop soil and other materials.
Also, the top is rounded and does not allow for foot placement. Do not use as teko (lever). It is also140

called kakusuko for short.
[Double sukoppu] (double spade) These spades can poke through the ground to dig a deep hole. The
dug soil can be grabbed under the surface and pulled out. It is used for digging holes for piles andutility poles.

Spear head spade

Square head spadeDouble spade[Tsuruhashi] (pickaxe) A tool used for excavating hard ground and breaking up asphalt.
[Reki] (rake) A tool used to level soil, spread asphalt, and collect fallen leaves. There are various
shapes and materials, depending on the purpose. Rakes for leveling soil have many thin tines, but rakes
for asphalt have none.
[Joren] (dredge hoe) A tool used to rake up earth, sand and debris.
[Tako] (manual compactor) A tool used to beat and pack soil and other materials by weight.
[Tamper] A tool with a flat metal plate attached to the end of a long handle. It is used to compactasphalt and other materials by holding the handle and tamping theRammersurface from above.
[Rammer] A machine used to compact the ground. The weight of therammer and the force of the impactor, which moves up and down,
compact the surface. It has strong striking power and is suitable forstrong compacting. There are engine- and electric-powered types.

[Vibro-compactor] A machine equipped with an engine to compact soil and sand by its own weightand vibration. Used for compacting road aggregate base layers, road subgrade layers, backfill, etc. The
machine is pushed and pulled back and forth by hand to compact the surface. Although the impact

141

force is inferior to that of a rammer, a large area can be compacted at once. A similar machine is theplate compactor. A plate compactor is more suitable for flattening due to the larger area of thecompacting plate and smaller vibration.
[Vibrator] A machine used to remove air bubbles from concrete and increase the density of theconcrete during concrete placement through vibration.

5.3.3 Layout Marking/Marking Tools[Sumitsubo] (line marker) A tool used for marking longstraight lines on the surface of a material.
[Sumisashi] (ink pot) The flat part of the ink pot is used fordrawing lines, and the round part (ho) is used in the same way

Line marker

as a brush.
[Chalk line] Similar to the sumitsubo line marker, but draws a line with powdered chalk.
[Laser marker] A machine that emits laser beams onto walls, ceilings, andfloors to produce horizontal, vertical, and other reference lines forconstruction. Laser beams are available in red and green. Green is relatively
easier to see in bright locations. Protective goggles for laser work are wornto prevent the laser beam from directly entering your eyes.

Laser marker[Marker pen, marking chalk] Oil-based pen for architectural use. For
example, it is used to allocate the position and pitch (distance between reinforcing bars) where thereinforcing bars are placed.
[Punch] This tool can be used to make small indentations in metal
surfaces by tapping with a hammer, or to make round holes incloth, leather, etc. The center punch is used to mark metal surfaces

142

Punch

(this is called marking).

5.3.4 Measuring/Inspecting[Level] A leveling device used to determine the height necessary

Levelfor the work. Mounted on a tripod, the device is manually leveledby balancing the built-in bubble vial. A level with an automaticleveling mechanism is called an auto-level.
[Laser level] An instrument for level surveying by laser and isused to determine the height necessary for the work.
[Transit] An instrument that measures the vertical and horizontal
angles based on the viewpoint supporting a small telescope. It is
used on a tripod. These days, a digital display type of device called

Transittheodolite is often used.
[Total station] A surveying instrument that combines a light-wave rangefinder and an electronictransit. Look through the telescope and simply align the crosshairs with the target and press the button
to simultaneously measure the distance and angle from the reference point. Total stations are used ina wide range of surveying applications, including topographic surveying, construction site location
management, initial ground surveying, and fixed point surveying.
[Mizuito] (line level) Thread used to straighten lines and matchheights when building foundations or stacking bricks and blocks. It
is made of non-stretch material.
Line level[Suiheiki] (level) A tool used to check whether a construction
surface or object is level with the ground. The level is checked bylooking at the air bubble in the vial. Some use the needle to checkthe level, and some are digital levels. Levels with a built-in
Level

143

inclinometer are also used in residential installations.
[Sagefuri] (plumb bob) A weight with a pointed conical tip used to checkthe verticality of a pillar or other objects. The verticality is checked byhanging it from a plumb bob holder fixed to a post using a thread andchecking if the distance between the surface to which the holder is
attached and the thread is constant.
[Sashigane] (carpenter’s square) A tool made of stainless steel or other

Plumb
bob

metal, used to measure right angles. It is scaled and can also be
used to measure length. The front side is in metric scale, and theCarpenter’s squareback side is 1.414 (√2) times the front side.
[Ogane] (triangular ruler) A large triangular ruler formeasuring right angles. It is made on site using the Pythagorean
theorem, the ratio of 3:4:5 . The 3:4:5 is called sashigo at the worksite.
[Measure] (tape measure) A tape-like tool for measuring length. Sometimes referred to as makijaku(tape measure). Available in steel and vinyl.

Convex[Convex] (retractable steel measuring tape) A measure with athin metal tape that measures length. Sometimes abbreviated asconbe, the official name is the convex rule.
[Jogi] (ruler) A tool used for measuring length and drawing straight lines. Materials include aluminum,
stainless steel, and bamboo. To avoid damaging materials such as fittings, bamboo rulers are used.

Aluminum ruler

Stainless steel ruler

144

Bamboo ruler

[Slump kenjaku] (slump scale) An instrument used to measure
the slump value (the lowered height after the slump cone isremoved) in the slump test.
A slump test being
conducted

5.3.5 Cutting/Bending/Breaking[Nokogiri] (saw) A tool with many blades (called me (teeth)) on a metal plate, used to cut wood, metal,
pipes, etc. It is called noko for short.
[Hasami] (scissors) A tool used to cut objects between two blades.
[Kuikiri] (end nipper) A tool used to cut objects between theblades. Used for processing tiles, cutting wires, etc. It can also cut
the head of a nail.
End nipper[Cutter knife] (box cutter) This knife can maintain its sharpness
by breaking off the tip of the blade.

[Tagane] (masonry chisel) A stick-shaped tool with a blade on one end that can be used to cut thinmetal by tapping it with a hammer. It is also used for hatsuri sagyo (breaking), to break concrete andmark measurements of roof tiles. Flat masonry chisel, concrete masonry chisel, carving masonry chisel
and others are available depending on use.
[Penchi] (pliers) A tool for bending, cutting, etc. There is a part for gripping with fine grooves toprevent slipping and a part with blades for cutting.

Box cutter

PliersMasonrychisel145

5.3.6 Tapping/Pulling[Hammer] A tool used to strike things. The material of thestriking head can be metal, rubber, or wood, depending on theintended use. Those with a metal head is sometimes calledkanazuchi.
[Rubber hammer] A hammer with a rubber head. It ischaracterized by its strong striking power without damaging the

Example of a hammer (for ringlock
scaffolding)Rubber hammer

material. It is used to compact concrete by tapping theformwork and making it vibrate during the concrete placing
process.
[Kizuchi] (wooden hammer) A hammer with a head made ofwood. Although the striking force is weaker than that of a metal hammer, it is less likely to damage
the material.
[Kakeya] (large wooden hammer) A large wooden hammer used for driving stakes, etc. Kakeya isalso used to tap hozo (tenon) into hozo ana (mortise) in the wooden-frame structure method.
Wooden hammer

Large wooden
hammer[O-hammer] (large hammer) A hammer with a long handle and a large head. It is used for pile driving
and demolition work.

146

[Bar] (crowbar) A metal tool that can be used as a lever. The L-shaped tip has a groove for removing
nails. The tip is inserted under the nail head, and the nail is

Crowbarremoved using the principle of leverage. The other side is either aclaw or flat like a spatula. In addition to pulling out nails, a large
crowbar can be used to lift heavy objects. It can also be inserted
into a gap for twisting and prying. A large crowbar is used in the dismantling of the formwork.

5.3.7 Filing/Polishing/Boring[Toishi] (grindstone) A tool for cutting and polishing metals, rocks, etc. The small rectangular-shaped
tools are used to sharpen the blades of nomi (wood chisels) and kanna (Japanese hand planes).
[Yasuri] (file) A tool for polishing metal and wood surfaces. There are many types of files for different
purposes, such as metal files and wood files. If chips get stuck in the grooves, a wire brush is used tocarefully remove the chips.
[Sandpaper] A type of yasuri (file) where sand or glass-like grains are applied onto the surface of
paper. There are several types of paper, including taisui paper (water-resistant paper) that resists watersand nuno paper (cloth paper) that has strength. The numbering indicate coarseness. The smaller thenumber, the coarser the grain, and the larger the number, the finer the grain, resulting in a smootherpolished surface.
[Wire brush] A stiff brush made of metal wires. It can be used to remove rust from metal, peel off
paint, and clean file grooves.

147

Wire brush

Wire brush

5.3.8 Tightening/Fixing[Monkey Wrench] A wrench that has a mechanism that opens

Monkey wrenchand closes. The width between the upper and lower jaws can bechanged to match the diameter of the bolt or nut. The upper
jaw is integrated with the grip, so the force should be applied
to the upper jaw when turning. Because the tip is open, this tool is classified as spanner, but it uses theword “wrench” as an exception.
[Socket wrench] A wrench used for nuts and bolts of various sizes by changing the sockets on thehead.
[Box wrench] A wrench in which the socket part for turning nuts and bolts and the handle part are
integrated as a single piece. There are L-shaped and T-shaped types.
[Rokkaku wrench] (hexagon wrench) This tool has a hexagonal

Hexagonwrenchhole and is used to turn bolts. Also called rokkaku bo wrench.
[Screwdriver] A tool used to turn screws. There is a Phillips-headand a flat-blade screwdriver to fit the grooves on the heads of thescrews. It is important to use the correct size to avoid breaking
the groove of the screw head (called nameru (stripping)). The
shape of the grip is also important. For example, the grip of a148

Screwdriverscrewdriver for electrical work is round and large so that the hand can easily wrap around it.
[Kugi] (nail) Something that is hammered in to join members together.
Depending on the application, there are various types of nails, such as

Nailscrew nails, concrete nails, casing nails, and corrugated roofing nails.
[Neji] (screw) A cylindrical or conical shaped object with a spiralgroove that is screwed into a member using a screwdriver to secure it
to another member.
[Tapping neji] (self-tapping screw) A screw that threads its own groove into the material as it is being
screwed.
[Bolt] A type of screw. A bolt (male thread) and a nut (female

Nut

Bolt

thread) are used as a set. A washer may also be used.

Washer

5.3.9 Kneading/Mixing[Hand mixer] A mixer for paint, mortar, and concrete. Ingredients are placed in a mortar box or bucket
and mixed with a hand mixer.
[Kakuhanki] (stirring machine) A machine for mixing liquids and construction materials. Also
called mixers, various types are used in construction sites.
[Mortar mixer] A machine that mixes cement, water, and sand to make mortar. There are two typesof power sources: one that uses a 100 V power source and the other an engine type.
[Concrete mixer] A mixer designed for concrete, with morestrength than mortar mixers.
[Batch Mixer] A mixer that mixes materials for concrete one
batch at a time.
Concrete mixer[Torobako] (mortar box) A sturdy box for mixing materials to149make concrete or mortar. Also known as torobune or fune. The ingredients in the mortar box are
kneaded using a stirring machine or a kneading shovel.
[Furui] (sieve) A tool with a mesh that can sort materials according to size. Items to be removed aresorted according to the size of the mesh. For example, it can take excavated earth and sand and separate
fine soil from gravel.

5.3.10 Curing/Prepping[Yojoyo poly sheet] (plastic sheet for curing) Polyethylene film in sheet form. It is used for moistureproofing and waterproofing from the ground when pouring concrete, for curing when painting, and toprotect from rain and dust.
[Veneer] (plywood) Thin plywood is laid to protect the floor from scratches.
[Blue sheet] Used to protect walking areas of the floor from paint and dust.
[Hisan boshi net] (anti-scattering net) A mesh-like sheet for scaffolding that covers the entire
building. It is also used to prevent construction materials accumulated on site from scattering, andcargo from falling off the rear decks of transport vehicles.
[Suichoku yojo net] (vertical safety net) A net attached toscaffolds at construction sites to prevent materials from flying
and falling from scaffolds.

Horizontal safetynet[Suihei yojo net] (horizontal safety net) A net used atconstruction sites to avoid humans and materials from fallingfrom heights.

5.3.11 Scrubbing[Brush] A tool with bundles of bristles planted at regular intervals onto the base, used for rubbing to150

remove dirt. For example, in stonework, a brush wetted with water is used to remove the excess cement
slurry from between the stones.
[Sponge] Foam-molded synthetic resin such as polyurethane, wetted with water and used to remove
dirt. For example, in stonework, it is used to clean surfaces dirty from cement slurry.
[Wes] (rag) Cloth used to wipe off stains from machine oil and other liquids.
[Bucket] A container with a handle for holding and carrying water. For construction purposes, sturdy
buckets made of galvanized steel sheets are used.
[Hishaku] (ladle) A tool with a handle for ladling water.

5.3.12 Carrying Things[Ichirinsha] (wheelbarrow) A tool for carrying items,

Wheelbarrowconsisting of a steel bucket with one wheel in the front. Usedby holding the handles and pushing. It uses the lever principlewith the wheel as the fulcrum, the handles as the effort, andthe bucket as the load to make it easier to carry heavy objects.
Sometimes called neko.
[Daisha] (wheeled platform) A platform with four casters,

Wheeledplatform

used to carry objects. Some have handles and some do not. A
wheeled platform with brakes is also available.
[Sori] (sled) A tool used to move heavy objects such as stones
by putting them on top and pulling it.
[Koro] (log) A log used to move heavy objects. Several are placed parallel to each other, an object isplaced on top, and the object is moved as the logs roll.

151

[Forklift] A vehicle equipped with forks that move up anddown using hydraulic pressure. Objects placed on the fork areraised to or lowered from high places.

Forklift5.3.13 Hanging/Lifting/Pulling[Winch] A machine that winds up a rope. Also called makiageki.
[Wire rope] Several high-tensile-strength steel wires are

Wire rope

twisted together to form a strand, and then several strands are
twisted together again to form a rope. It has high tensile
strength, excellent impact strength, and flexibility for easy

Shacklehandling. Those with processed ends are used for slinging.
There are also ropes for anchoring.
[Shackle] A slinging fixture for connecting a wire rope or chain to a suspended load.
[Turnbuckle] A device used to tighten ropes and wires.

ShackleTurnbuckle

152

[Chain block] A machine that can raise and lower heavy objects by

Chain block

applying the principles of lever and pulley. It is used by attaching it
to a tripod, etc.
[Lever hoist] A machine that has the same mechanism as a chain
block, but is smaller than a chain block. It is used to secure the load,etc. For example, when a backhoe is loaded onto a truck fortransportation, it is also used to secure the backhoe so that it does not move.
[Oyazuna kinchoki] (main rope tensioner) A device thatcan keep the tautness of the main rope to which the hook of

Main ropetensioner

the safety belt is attached. It is used when working at heights,
such as scaffolding work.
[Tirfor] A manual winch used for pulling heavy objects. The
wire rope passed through the tirfor can be pulled strongly by lever operation. When felling a large tree,
pulling the tree with a tirfor can bring it down in the desired direction.
[Jakki] (jack) A device for lifting heavy objects with a small amount of force. The lifting mechanism
includes screws, gears, and hydraulic pressure.
[Kirin jakki] (screw jack) A device that can lift heavy objects vertically by using the thrust generated
when the screw is turned. It is also used to apply force to the left or right by placing it between two
horizontal members in soil retaining structure work.
[Lever block] A tool for lifting and securing loads. It is also used to re-align steel frames (to makethem vertical).

1535.3.14 Work Platforms/Ladders[Hashigo] (ladder) A tool for climbing to high places. It is climbed by stepping onto the rungs. It
should be set at an angle of approximately 75 degrees. If the angle is too steep, there is a risk of falling
backwards. Conversely, if the angle is small, there is a risk of the ladder breaking. Also, always workwith an assistant to support the ladder.
[Kyatatsu] (stepladder) A tool that is a combination of twoladders. When opened, it can be used as a ladder. When using it
as a stepladder, do not sit or stand on the top. Also, do not work
while straddling the top with legs on either side, as this may upset

Stepladderthe balance and be potentially dangerous.
[Kahanshiki sagyodai] (portable elevated work platform) A

Portable elevatedwork platform

tool with a platform between two legs that extend and retract. Also
known as nobiuma. There are handrails on top of the work
platform. Leaning outward or pushing against a wall may cause
loss of balance and falling.
[Rolling tower] A platform for working at heights. There are
casters on all four corners to move it around. There are safety standards for rolling towers under the
Industrial Safety and Health Act.
[Kosho sagyosha] (aerial work platform) A vehicle equipped with a device that can raise and lower
a man basket to a height of 2 m or more.

5.3.15 Cleaning[Hoki] (broom) A tool for cleaning by sweeping. Bamboo branches, bundles of plants or synthetic
fibers are attached to the end of a stick.
154

[Chiritori] (dustpan) A tool for collecting dust and debris swept with a broom.
DustpanBroom[Blower] A blower. It is used to collect light objects such as
fallen leaves by blowing them with the force of air.

155

BlowerChapter 6: Knowledge of Construction Site Work
6.1 Matters Common to Construction Sites
Construction sites are home to technicians from many job categories. Although the work they
perform may appear to be different from each other, experienced technicians are always aware ofcertain matters. This realizes high quality and safety. This section describes matters that all technicians
should know.

6.1.1 Characteristics of Construction Work
(1) Construction work is on a build-to-order basis.
The term build-to-order refers to the manufacturing of a single product designed from scratch tomeet the customer's requirements, rather than the repeated production of the same design in factories,
as in the case of automobiles. Construction work is conducted on a build-to-order basis. They are
diverse, from large-scale to small-scale projects, and although some may appear to be similar, eachindividual project has different characteristics and conditions. It is important to have the intention ofbuilding-to-order for each customer.
(2) Construction work is subject to location constraints.
The majority of construction work is built in accordance to the unique requirements of the locationfor each property, which means that a project will never be repeated under the same conditions.
(3) Construction work is subject to nature.
Construction work is often conducted outdoors and subject to uncertain factors, such as topography,
seasons, weather and other natural conditions.
(4) Construction work is subject to social constraints.
Construction work is local production, and therefore is subject to social constraints on the site. It is
important to manage the site based on safety measures for the surrounding area and environmental
preservation measures. Applicable laws and regulations and the surrounding social environment differ
156depending on the location of construction, and construction work is expected to conform to these
constraints.
(5) Quality is created through safe process.
It is also true in construction work that the quality of the finished structure is created through theentire safe construction process.

6.1.2 Construction Plan
All construction projects have a construction plan. A construction plan is a plan for the construction
project based on the terms and conditions of the construction contract, drawings, specifications, site
descriptions, and other design documents. The construction plan is prepared considering the following
points.
> Planning within various social constraints, such as relevant laws and regulations.
> Comprehensive planning of management methods for quality, construction budget, process, safety,
and environmental preservation.
> Planning to efficiently combine construction methods to achieve good quality at minimum costthat is completed within the construction period.
> Planning for accident-free and disaster-free project that considers environmental preservation.
> Planning using the 5Ms of Construction Management. The 5Ms of Construction Management
refers to Manpower, Materials, Methods, Machinery, and Money.

> Conducting sufficient preliminary investigation to understand the local/on-site conditions, etc.,
and planning measures and management methods prior to and during construction.

6.1.3 Construction Management
Construction management is the management necessary for the contractor to complete the157construction target in the prescribed quality in accordance with the construction plan. Construction
site work is conducted under the following five management indicators (called QCDSE).
[Quality]This is management to produce a finished structure that fully satisfies the quality required by theclient. Quality inspections, quality tests of materials and various construction tests as stipulated in thequality control plan are performed to control the ensure prescribed dimensions and shapes.
[Cost]
Cost is money that can be spent on site. The cost of materials, labor, and field expenses related tothe construction project are managed so that they do not exceed the construction budget.
[Delivery]
Companies coordinate with the prime contractor and other contractors in order to ensure that theirconstruction work can be performed efficiently, and manage the construction process to avoid delaysin the actual work so as to ensure completion within the construction period.
[Safety]
Necessary management is conducted to prevent accidents such as people and objects falling, and toprevent work-related illnesses such as pneumoconiosis and heat strokes. In addition, risk prediction
training in the daily cycle of safety in construction, patrols during work, safe process meetings, 5S
promotion activities, and other activities are conducted with the goal of achieving zero accidents andzero occupational injury.
[Environment]This is management to minimize the impact of construction on the environment, including noise,
vibration, and water pollution. The standards set by laws and ordinances must be observed.

6.1.4 Pre-Construction Preparations（１） Main considerations for the construction procedure manual158

In order to ensure high quality in construction work for the day, it is necessary to check and correctly
understand the construction details.
> Review and understand the terms of the construction contract.
> Review and understand the contents of the contracted construction (terms and conditions of theestimate) and the scope of work.
> Review and understand the blueprints and construction drawings.
> Review and understand the site construction conditions and site rules.
> Review and understand the work schedule with other contractors and connections withconstructions before and after the project.
> Confirm the construction procedures, allocate workers, and prepare materials and equipment.
> Confirm possession and carrying of the Career Up Card and licenses required for the work.
> Identify and understand safety issues.

(2) Pre-work inspection
When working on a construction site, workers use a variety of tools and machinery. Common
accidents for workers occur when handling tools and equipment. Be sure to conduct the following as
pre-work inspection.
> Pre-work inspection of the machinery- Confirm that machinery capable of conducting the intended work are in place, inspected, andmaintained.
> Checking of equipment, tools, and instruments- Confirm that the equipment, tools, and instruments to be used are inspected and maintained.
> Confirmation of work procedures- Confirm that the workflow is realistically feasible.
- Confirm that individual work sharing and collaborative work are assigned in a compatible
159

manner, and that the work assignment is correct.
> Confirmation of safety- Confirm that health and safety protective equipment and safety devices, etc. are being usedcorrectly.
- Confirm whether emergency responses are appropriate.

6.1.5 Layout Marking (Marking Out)
Sumidashi (sumitsuke) (layout marking (marking out)) refers to marking the location and height ofthe structure or component to be constructed on the construction site. In the entire construction processfrom beginning to completion, this is the very first step. It is the most important work that requires
quality (accuracy). Precise reference marking and reference level, axis line as per blueprints, etc. aremarked for correct positioning. For layout marking, a tool called a sumitsubo (line marker) is used,
but nowadays a laser illuminator is used to emit a laser beam to mark along the laser. The laser makes
it easy to check for level and right angles. The following are the three main types of layout marking
and marking out work.
Layout marking and marking out

Layout marking and marking out locations

work
Layout marking

Reference and parent markings for positioning, height(reference level/GL), axis line, etc.

Marking out for member fabrication

Cutting and processing dimensions of reinforcing bars,
formwork, piping, wiring, and other components;
processing dimensions of wooden workpieces; and scribe
marks on sheet-metal

Marking positioning of processed

General interior and exterior fittings, intake and exhaustparts, equipment, hardware, etc. forvents such as ventilation holes, water supply and drainage

installation

sanitary piping, air conditioning and sanitary equipment,
and firefighting equipment160

6.2 Construction Knowledge of Each Specialty Work
This section provides an overview of each specialty work and the key points to keep in mind to
avoid accidents and compromising quality. For unfamiliar terms, see Chapters 4 and 5.

6.2.1 Scaffolding WorkAs explained in Chapter 3, there are many different types of scaffolding work. This section describes
scaffolding construction. There are several types of scaffolding, including timber scaffolding, tube
scaffolding, framed scaffolding, and ringlock scaffolding, but there are some construction tips that arecommon to all types of scaffolding work. It is to make sure that the footing is secure, then assemble itso that it is vertical and level, and diagonally brace it to keep it straight. To prevent the entire scaffold
from collapsing, when there is a building, it is secured to the building with kabetsunagi (wall tie
anchors). When there is no building, it is braced with circular hollow sections or other means.
(1) Foundation of scaffolding
The ground on which the scaffolding is erected is compacted for strength. If even one upright tube
sinks, the entire scaffold can crumble. In addition, the ground is made as flat as possible so that there
are no gaps between the mudsill and the ground.
(2) Fixing the legs
The base fitting is nailed to the mudsill laid on the
ground.

MudsillBase fitting161

(3) Installation of upright tubes and planks
Upright tubes are erected vertically, and planks should be attached perpendicular to the upright tubes.
The footings of the upright tubes are connected toUpright tube

Working
platformeach other by horizontal members to secure them.
(4) Installation of beams and working platform

Beam

Connect the upright tubes on the front side (thePlankbuilding side) and the rear side (the outside) using
braces, and attach the scaffold board (working platform) on top of it.
(5) Installation of stairs, handrails, middle and lower ledgers, and toe board.
Install handrails for workers, middle and lower ledgers for fall prevention, and toe boards to prevent
tools and other items from falling. Handrails are also installed for stairs.
(6) Installation of cross braces
Install large cross braces to keep the entire scaffold vertical and level.
Cross brace

Handrail
Lower ledger

Toe board

Stairs(7) Installation of wall tie anchors
To prevent the entire scaffold from collapsing, it is secured to the side of the building with wall tie
anchors. If there is no building, diagonal supports (yarazu) are installed using circular hollow sections
or similar members.

162

6.2.2 Steel Framing WorkIn steel framing work, steel sections are assembled to complete the framework of a building. It is
performed in the order of steel section fabrication, foundation frame construction, and steel section
erection.
(1) Steel section processing
The steel sections are fabricated in the factory. A construction plan is drawn, and the steel sections
are cut accordingly. The cut steel sections are assembled and welded, and the welds are inspected byultrasonic testing. After inspection, they are coated with rust-proofing paint and transported to theconstruction site.
(2) Foundation frame construction
Anchor bolts are secured to the nonstructural concrete withanchor bolt stands or other means. This is followed by the

Example of base plate
installation

placement of the underground beams and foundation
reinforcement, foundation formwork, and foundation concretepouring.
(3) Steel frame erection
Steel columns and anchor bolts fixed to the foundation are joined to each other by a member calleda base plate. Foundation work in steel construction is just as important as that in scaffolding
construction. For example, foundation heights may vary slightly, which, if not adjusted, will affect theaccuracy of the overall building finish. Check the height of thefoundation and match the base plate height of all columns

Steel section
Anchor bolt

Base plateNon-shrink mortar

using non-shrink mortar or layers of thin steel plates. Aftermaking sure the mortar has set, check the orientation and bolt

Foundation

the columns in place.
There are two methods of fastening the upright members to163

Fixing steel frames with baseplatesthe beam: bracketed and non-bracketed. In the bracketed method, the beam is divided into three
sections, and the two ends of the beams and the columns that cross those ends are bracketed together
by welding or other means at the factory. The non-bracketed method is a construction method in whichcolumns and beams are joined directly on site.
The intersection of columns and beams are bolted and then welded. If the holes for the bolts do notmatch, a tool called a drift pin is used to align them before securing the bolts. At this stage, the nut is
temporarily fixed.
By adding beams, the columns will be pulled and will not be able to maintain their verticality. The
frame is pulled with wires to re-align the steel frames, then the nuts are tightened properly, and thenthe intersection is welded (stud welding).

6.2.3 Steel Reinforcement Work (Rebar Work)
Concrete is resistant to compressive forces but weak against tensile forces. Because of its tensile
strength, rebar can be placed in concrete to compensate for the weakness of concrete.
Rebar can oxidize and rust. Concrete is alkaline, which
protects the rebar from rust, but over time it will become more
and more neutral. If neutralization progresses to the rebar, therebar will rust. Therefore, when placing the reinforcement, it
is important to ensure a certain distance from the surface ofSlab concrete cover
thicknessthe concrete, or kaburi (concrete cover thickness).
In order to maintain strength, it is necessary to use rebar ofa specified thickness and to distribute the rebar with proper
spacing between the rebars. Tape is wrapped around the rebar
to make it easier to check the pitch.
In the case of thin slab rebars, the bars are joined by a
164

Pitch confirmation tapemethod called rebar lapping. This joint method gains strength from the concrete's adhesion to the rebar,
but because the strength of the concrete affects the strength of the joint, make sure to secure a sufficient
length of overlap and secure the bars with binding wires.
Rebar work is involved throughout the entire construction in a typical RC structure building. In
particular, it is closely related to formwork carpentry, and the processes need to be coordinated witheach other. In addition, meetings with electric technicians will be necessary for piping and wiring workfor electricity and equipment, and with plumbing technicians for water supply and drainage. Rebar
work is performed in the following order: rebar fabrication, foundation reinforcement, and floor slab
reinforcement.

(1) Rebar processing
Construction drawings are based on structural drawings calculated by a structural design specialist.
From the construction drawings, the required shapes and sizes of rebar and the required number of
each are calculated, and a reinforcement detailing is created. Rebar is cut, bent, or otherwise processed
according to the reinforcement detailing. In addition, bar tags are created based on the reinforcement

Rebar bending

Rebar cutting

detailing. Bar tags are attached to the fabricated rebars and are used for sorting and receipt inspection
at the time of delivery.

165

(2) Foundation reinforcement
Rebar delivered from the processing plant is inspected upon receipt and organized for ease of
retrieval in subsequent operations. The foundation reinforcement work begins by layout marking theexact location of the foundation onto the nonstructuralconcrete. After layout marking is complete, embedded
beam bearing brackets are lined up to keep the main beambars of the foundation at a level height, and secured withnails or anchors for nonstructural concrete. Spacer blocks

Foundation beam
reinforcement

are used to lift the base reinforcement to ensure cover
thickness. After the base reinforcement, the column reinforcement is placed. A column consists of amain rebar placed perpendicular to the ground and hoop rebars surrounding the main rebar. Hoop
rebars are installed to reinforce against shear and to prevent the main bar from shifting due to shaking
caused by earthquakes and other shocks. Once the column rebar and hoop rebars are bound, spacers
are installed to secure the cover thickness. After the column rebars, the beam rebars are placed. Afterall the foundation reinforcement is completed, the formwork is erected and the foundation concrete ispoured.
(3) Reinforcement of doma (ground under the house)
Typically, pipe burial and backfilling are performed prior to doma reinforcement. Doma
reinforcement is placed in the following order: main rebar placement, distribution rebar placement,
and installation of spacers. After completing the doma reinforcement, the doma concrete will be
poured.
(4) Frame reinforcement
The frame provides the reinforcement for the walls, beams, and slabs.
Wall reinforcement is placed in the following steps: checking the cover thickness, checking theinternal/external relationship of longitudinal and transverse reinforcement, allocating the pitch and166placing reinforcement, placing reinforcement for openings reinforcement, placing spreader rebars, andplacing spacer blocks.
Beam reinforcement is placed in the following order: placement of bottom rebars, temporary
placement of hoops at the ends, placement of top rebars, placement of bottom and top rebars of small
beams, pressure welding, placement of stirrups and tying to top rebars, placement of side and spreader
rebars, dropping into the formwork, and placement of spacers.
The slab shall be doubly reinforced with bottom and top reinforcement consisting of main rebars
and distribution rebars.

Top rebars<Basic composition of beams>
StirrupSpreaderrebarsSpacerSide
rebarsWallformwork

Dropping in

Bottomrebars

6.2.4 Rebar Splicing Work
There are several types of rebar splicing methods, but
no matter which method is used, the spliced joint musthave strength equal to or greater than that of the base rebar.
For example, the splice cannot be detected when viewing
a cross-section of a perfectly executed gas pressure

Tensile test

welded splice, and when a tensile or bending test is performed, the splice does not break, but insteadthe base rebar does. The following steps are used to check the process while performing pressure
welding.
167

(1) Checking rebar butts
Check for bends in the rebar.
(2) Processing of rebar butts
Rebars are cut by push-cutting at steel construction sites, and therefore their butts are unsuitable forpressure welding as they are. Since the cut surface oxidizes over time, the rebar is cut using a coldcutting, right-angle rebar cutter on the same day that pressure welding is performed.
(3) Mounting onto the welding fixture
Make sure the welding faces of the rebars are clean before setting them to the welding fixture usingbolts. Because high pressure is exerted onto the rebar during the pressure welding process, the bolts
should be securely fastened so that they do not loosen during the course of the work. When fixing,
check the size of the gap between the butts to be pressure welded.
(4) Heating and pressurizing
First, the part where the rebars are butted together is heated with a burner, and the heated portion is
gradually expanded to the left and right. The approximate range to be heated is about twice thediameter of the rebar. Simultaneously with heating, pressure is applied to press the butts together. The
butts will gradually bulge out, and the work is finished when they reach a predetermined size.
Work process of gas pressure welding

Hold
Cleaning

Reducing
flame

Neutralflame

Initial pressurization

Neutralflame

Reducing
flame

Apply
pressure

Bulge formation

168

(5) Inspection
The size, length, shaft misalignment, bending, cracks
and dents on the exterior, and bulkiness of the bulge are allinspected.

Examples of bad bulging

6.2.5 Welding WorkArc welding is a necessary technique in many areas of construction work. If the current is too low,proper welding cannot be performed. If the current is too high, the member will melt and create a hole.
Proper and constant distance should be maintained
Arc welding work

between the welding rod and the material to bewelded, without getting too close. A proper weld willproduce a weld scar that looks like a line of shells.
Welding is an easy task for anyone to do once thebasics are mastered, but it is important to takeprecautions against physical effects and accidents.
Arc welding uses electrical power to weld metals together, so avoiding electric shocks is the priority.
Even more important is the prevention of effects on people. Inhalation of fumes from welding (metal
vapors cool and solidify in the air and become individual particles floating in the air, which appear
like smoke) can cause symptoms such as headaches, fever, chills, muscle aches, thirst, and fatigue.
Dust masks should be worn to prevent fume inhalation. Also, wear light-shielding glasses or welding
face shield to protect your eyes from harmful rays. The welded area is polished with a grinder, at whichtime metal dust adheres to gloves and hands. Avoid rubbing your eyes polishing, as rubbing your eyes
can damage them.

1696.2.6 Formwork Carpentry
When fresh concrete is poured into a formwork, theFormwork carpentry

formwork is subjected to several times the pressure of
the same volume of water. Insufficient reinforcementof the formwork can lead to accidents where theformwork breaks (blow-out) and ready-mixed
concrete flows out. In order to prevent blow-outs, the formwork must be adequately reinforced towithstand the pressure of the concrete. Also, since placing concrete from height may result in a blowout, a detailed discussion is held with the concrete pumping contractor regarding the concrete
placement method.
The formwork should be erected in the correct position, vertically and leveled, and should beassembled so that it can withstand loads, lateral

Tightening form ties

pressure, vibrations, impacts, etc., without significant
deformation or damage.
Wall formwork should be made from materials suchas separators, form ties, and P-Con to ensure that there
are no misalignments or errors. Form ties can also betightened through circular hollow sections to make them stronger.
The slab is supported vertically from below because the weight of the concrete will be applied
directly in the vertical direction. The materials used are, from the bottom, pipe supports called shoring,floor joist hanger, and floor joist, on top of which formwork plywood (also called sekiita in formwork
carpentry) is attached.

170

<Slab structure>

Floor joist hanger

Formwork plywood

Floor joist tube (circular hollow section)

Pipe support

A sufficient number of pipe supports are required to support the slab. To prevent the shoring fromsliding, the footings are connected in two horizontal directions by pipes called negarami. If the pipe
support is longer, horizontal joints are installed using every 2 m or less in height using circular hollow
sections. Finally, the chain, turnbuckle, and support are used to push and pull while checking theverticality and the axis line as adjustments are made.

6.2.7 Concrete Pumping Work
Concrete pumping work involves pouring ready-mixed

Acceptanceinspection

concrete delivered by truck agitators into formwork using
pump trucks. The ready-mixed concrete brought inundergoes acceptance inspection (slump value, air content,
and chloride content) based on the ready-mixed concretedelivery note, and a test piece for compressive strength inspection is prepared at the same time.
An important thing to do before starting the pouring work with the pump truck is to prepare theground to put out the outriggers that secure the pump truck so that it will not fall over. To prevent theoutriggers from sinking into the ground due to vibration, the outriggers' jacks are supported by the171receiving wood on solid ground, and on softer grounds, thepump truck is installed by laying a steel plate and thenopening the outriggers to their maximum width. In
addition, tire stops should be securely inserted. On sloping
terrain, adjust the outriggers' jacks so that the horizontal

Concrete placement by a pumptruck

angle is within 3 degrees both front to back and left to right.
During construction, care must be taken to avoid contact with or cutting power lines due to boom
movement. In the case of high-voltage wires, even without direct contact, the spark discharge may
cause electricity to flow and cause electric shocks. Check and observe the safety clearance distance(distance away from the wire).
It is also important to inspect the delivery pipes and check connections. If a delivery pipe ruptures,
ready-mixed concrete will flow out, leading to an accident. It should be inspected on a daily basis by
tapping (checking the sound when tapped) or ultrasonic thickness gauge. Pipes are to be handled
carefully to avoid damage during loading and unloading.
Before placing the ready-mixed concrete, a primer is sent through the delivery pipe first to makethe inner wall more slippery. This primer is discarded, because when cast into the formwork, it
compromises the strength and quality of the concrete. About 1.5 times the amount of the primer,
including the primer, is not placed in the formwork, but instead discarded.

6.2.8 Painting Work
There are many different types of painting work. The important thing common to all types is tomake sure that the paint adheres well to the painted surface. If the work is not done properly, problems
such as the paint film cracking or peeling and loss of luster will occur after one to three years.
Painting is basically divided into three processes: primer, middle coat, and top coat. It is importantthat appropriate amount of time is passed between each step of the process in order to let the paint dry,172

which is called the process interval period. The time between painting processes must be at least as
long as specified for each coating, and the coating must be allowed to dry thoroughly before moving
on to the next painting process. Process interval periods vary depending on a variety of conditions,
including temperature, insolation and humidity, and the worker must be able to assess the situation inproceeding with the work. Construction should not be performed when the humidity is 85% or higher,such as during rainy weather.
Before starting priming, make sure the painted surface is free of debris. This process is called keren(scraping). If the exterior walls are to be painted, dust and dirt should be removed by high-pressure
washing or other methods, and cracked areas (cracks) should be repaired.
The primer coat is applied to improve adhesion between the substrate and the middle-coating
material. Sealer, primer, filler, and other priming materials are chosen for different purposes.
The middle coat smooths out surfaces that have become uneven due to scratches or cracks in orderto achieve an even finish. It can also reinforce and enhance adhesion of the topcoat material.
The top coat is the final stage of the painting process, and its finish demonstrates performance inweather and stain resistance as well as design for

Spray painting

aesthetic purposes. The performance of the painting
work is determined by three layers of paint (primer,
middle coat, and top coat), but is generally evaluatedbased on the performance of the top coat paint. In
spray painting, the surface usually receives two coats.
Paint should be applied only where necessary, and therefore, do not forget to cover the areas that do
not need to be painted. Cover the floor with apolyethylene sheet, apply masking tape to the borderof the area to be painted, and use masker tape to coverlarge surfaces such as walls. In addition, in exterior
173

Covering work

wall painting, paint can splatter onto cars, etc., causing problems. The entire building should becovered, and automobiles and other vehicles within the area where paint is likely to splatter are also
covered with sheets.

6.2.9 Plastering Work
Plastering is work in which knowledge and skill have a particular impact on the finished product.
Plastering requires a high level of skill to ensure that there are no imperfections when it comes to theflat finish. Plastering in general housing is also expected to contribute to the design, so it is a creative
job that requires not only technical skills but also a sense of style. The main tools used in plastering
are kote (trowels) and koteita (trowel boards), and many different trowels are used depending on thearea to be painted and the finishing method.

Outside corner trowel

Outside corner

Inside corner

Inside corner trowel

For example, the photo above shows the finishing of the middle coat on the outside corner and theinside corner. To press-finish, kiritsuke gote (inside corner trowel) is used for the outside corner andmenbiki gote (outside corner trowel) is used for the inside corner.
More than the surface coat that is visible as the finished product, the difference in technical skill isapparent in whether or not the base coat can be painted delicately and flatly. The base coat quality
directly affects the finish coat.

174

There are several types of base coats. For example, thephoto on the right shows the painting process of traditional
Base coat (arakabe)

Kyo-kabe/Juraku-kabe clay walls. First, the wall is
Middle coat

constructed of woven bamboo, onto which clay is applied in

Top coat

the following order: base coat (arakabe), middle coat, and top
coat. A more recent method is to apply a base coat on gypsum

Process of Kyo-kabe/Juraku-kabe walls

board or lath board, followed by a middle coat.

6.2.10 Carpentry Work
Carpentry work constructs wooden buildings. What is important in carpentry work is to know theproperties of wood and to master the use of tools. Wood is not a homogeneous material and has
disadvantages such as being prone to cracking and deformation. A worker unfamiliar with theproperties of wood can easily split the material during processing. For processing and assembly,
electric tools are used these days, but in general, tools that have been handed down from generation to
generation are also used. In particular, cutting tools such as nomi (wood chisels) and kanna (planes)
must be maintained by the workers in order to keep them sharp.
The traditional construction method is the jikugumi koho (Japanese timber framing) which
combines horizontal members such as foundations, beams, and girders with vertical members suchas columns. The diagonal members, called sujikai (cross braces), provide strength to the building as
a whole. Lumber is joined together by a combination of processed members called tsugite (splices)and shikuchi (joints). Splices and joints are intricately carved using wood chisels and kanazuchi(hammers), but recently, machine-made parts with high-precision cutting are also being used toassemble on site. In recent years, the spliced/joined parts are reinforced with hardware to provide
strength. After the concrete foundation is completed, the Japanese timber framing is carried out
according to steps (1) through (12) shown below. During the construction process, many craftsmen
175are involved, including those in plumbing, electrical, interior finishing, sheet metal, and roofing, so it
is important to work closely with them.
(1) Laying the foundation
On top of the foundation, a base for the columns is installed.
(2) Installation of the through column, hanger columns, outer floor beams, and beams,
A through column is a single-piece column that passes though the first- and the second-stories. It
serves to support the outer floor beams (called dosashi) on the second and third floors. Hanger
columns are columns that are specific to each floor.
(3) Temporary brace
Members are mounted at an angle to keep the columns vertical and prevent deformation of thetimber framing. This is called sujikai (cross brace).
(4) Installation of the second-story hanger columns, girders, and beams
The second-story hanger columns are erected on top of the first-story outer floor beams, andgirders and beams are attached. A girder is a member orthogonal to a beam.
(5) Vertical roof strut
Vertical members that support the roof (called koyatsuka) are attached.
(6) The purlin and the ridgepole
The purlin (the member that receives the rafters) and the ridgepole (the uppermost member of thetimber frame) are attached.
(7) Installation of rafters
Rafters to support sheathing and roofing materials are attached.
(8) Installation of sheathing
Sheathing is attached to the rafters. Sheathing is a component that serves as a base for roofing
materials.
(9) Completion of the framework
176

Construction up to this point completes the framework (joto). It is sometimes referred to as
muneage, tatemae, or tatemai.
(10) Installation of the cross brace
Install the cross brace and remove the temporary brace.
(11) Installation of wall studs and hold-down hardware
Wall studs (ma-bashira) are attached between the columns to serve as the wall base material. In
addition, reinforcement members called hold-down hardware are installed to prevent the columns
from being pulled out from the foundation and beams.
After the above construction is completed, roofing, interior, exterior, fittings, equipment, andelectrical work will be performed.

Rafter

The structure of the timber framing

Vertical roof strut
Dragon beam
Roof beam

Eave girder

Ceilingjoist

Cross brace
Floor
joist

Dragon beam

Outer floor beam
LintelInner floor
beam
Ceiling joist
Partition
girderThrough column
Windowsill

Floor joist
Floor joist
hangerHold-down hardware
Diagonal bracing
Hanger column

Subfloor
ventilation

Floor strut
Moisture-proofed
concrete
Moisture-proof
sheet
RebarsContinuous footing
foundation

Anchor bolt
Foundation

177

In addition to timber framing, there is also the 2x4 method, also called wakugumikabe koho. Panels
for walls and floors are made using 2 x 4-inch members andplywood, and panels are joined to each other using special
hardware. Compared to conventional Japanese timber
framing, traditional tools are used in very few situations,
2x4 method

construction is easier, and can be erected in a shorter
construction period.

6.2.11 Roofing Work
Material for roofing include clay tiles, cement/concrete tiles, slates, corrugated sheets, galvanizedsteel, copper sheets, and asphalt shingles. Clay tiles are used for Japanese houses, shrines, and temples.
Clay tiles have the advantages of long service life, heat insulation, soundproofing, and do not require
painting, but their disadvantage is that they are a bit heavier, so consideration must be given to theearthquake resistance of the building itself.
The purpose of a roof is shield and protect a building from rain and snow. Therefore, the mostimportant point in roofing work is waterproofing. The entire roof is waterproofed with sheet materials
such as asphalt roofing. Large flat areas of a roof rarely leak if the substrate is properly waterproofed,
but leaks are more likely to occur where flat surfaces are joined with another flat surface or a wall.
Such areas use special roof tiles and sheet metal fabricated components called mizukiri (flashing). In
the case of tile roofs, for waterproofing, the tile joints are filled with a material called nanban shikkui(nanban plaster) using kote (trowel).
Rainwater that travels down the roof will go around the edges of the roof and damage the building,so it is necessary to do amajimai (rain-proofing) work. Rain-proofing is a structure that directs
rainwater into gutters and down to the ground.
Japan lies long from north to south and the climate differs by location, so roofs suited to each region178are constructed. For example, in regions with heavy snowfall, a metal fitting called yukidome (snowguard) is installed on the roof. Without snow guards to prevent snow on the roof from falling down,snow can fall and break the eaves. Okinawa buildings use uniquely shaped tiles to protect buildings
from objects blown into the air by typhoons. It is also important to know that the shape of the roof androofing materials vary depending on the location where the work is to be done.
Roof valley

6.2.12 Architectural Sheet Metal Work
Architectural sheet metal work involves cutting, bending, punching, welding, and otherwise
processing thin metal sheets to create components that meet the intended use and install them. This
work is needed in a wide range of areas, including plumbing and roofing. The basic operations required
to process steel plates are scribe marking, cutting, bending, and welding. When making products withcomplex shapes, a technique called hammering is required. This is a task that requires high skill andtherefore it will be omitted here.
(1) Scribe marking
Scribe marking is done in a single step as much as possible, using scribing needles, dividers, andmetal rulers. When making several of the same item, gauges are made for efficiency.

179

Scribe marking(2) Cutting
The sheet metal is cut carefully, lifting the part to beretained by hand so that the scissors can easily enter.
Keep the eyes on the scribe lines and continue to cut
along the scribe lines. Cut edges are smoothed with a

Cutting

metal file.
(3) Bending
Using kage tagane (wide chisel) and a hammer, thesheet metal is tapped from the back side along the scribe
line. This way, the surface can be bent slightly in the

Bending

desired direction. Next, using an anvil or the corner of aplatform called surface plate as dollies, the piece is gradually bent to the required angle by tapping itwith a hammer.
(4) Welding
The welding method most commonly used in sheet metal welding is the fusion welding method, inwhich a filler metal (welding rod or wire) is melted to make the joint. Secure overlapping parts using
clamps. Next, temporarily attach the joints at a 10 mm pitch. The key to this welding is to melt thewelding rod while maintaining a set distance between the parts and the fire. This work requires
concentration and is therefore performed in a comfortable position.

1806.2.13 Tiling WorkWhen tiles come off, it is called hakuri (debonding). Also, tiles can detach and fall off, or hakuraku.
Tiles from high places debonding and detaching can lead to life-threatening accidents. In tiling work,
the most important thing is to ensure that the tiles do not debond or detach.
In a method known as acchaku-bari (mortar bed method), the substrate is coated with adhesivemortar, and tiles are pressed onto the mortar. The tiles have grooves on the back side called uraashi.
The tile is wiggled as it is pushed into place so the mortar goes into these grooves, and then tappingthem in with kizuchi (wooden hammer), tatakidai (tapping board), etc. A certain amount of time (opentime) must be allowed between the application of the adhesive mortar and the installation of the tiles.
Failure to take proper open time can cause debonding and detaching.
Because of the difficulties in taking this open time, kairyo acchaku-bari (the back-buttering method)
was invented. Mortar is applied to the substrate and the back of the tile, and the tile is pressed against
the substrate. Another idea was to apply adhesive mortar to the substrate surface, and then use a tile
vibrator for tiling. It is called micchaku-bari koho (the vibration installation method). This method canalso be used to finish the joints by pressing down the mortar rising up from the joints with meji gote(joint trowel). Another method is to use flexible tile adhesive instead of mortar. When adhesive is used,
it begins to harden about 30 minutes after application. Be systematic in determining the area to be tiled
and positioning them before the adhesive hardens.
Base coat

Middlecoat

Adhesive mortar

Frame

Mortar bed
methodBack-buttering
method181

Vibration installation
method

6.2.14 Interior Finish WorkInterior work is largely divided into steel stud framing, drywalling, and ceiling and floor finishes.
This section describes steel stud framing and drywalling. Both tasks may be done by one person, and
it is important to make sure to prepare tools, process and count materials, etc., so as not to interrupt
the flow of the work.
(1) Steel stud framing
Steel stud frames are divided into two categories:
partition frames, which are walls, and ceiling frames. Bothare installed according to the layout markings. Even if
there already are layout markings, do not begin work;
alwayscheckthelayoutmarkings

forChecking the layout
markings

walls,

doors/windows, fittings, equipment doors, etc. with the construction drawing.
To make the construction process more efficient, check the number of materials to be used andarrange them in such a way that they can be easily picked out according to the work procedure.
Scaffolding should be erected for ceiling work to makethe work easier. There are places inside the wall where
pipes for electrical outlets, gas, water, etc. run. These are
the jobs of other contractors, but it is important toMaterial
preparationconsider the interfacing when working so they do not
clash with the studs, which reduces rework.
(2) Drywalling
Gypsum board for drywalling can be easily cut by making a shallow cut with a box cutter and thenapplying force. Gypsum boards can be bent to some extent, so it can be fixed to gently curved surfaces
as it is, while gently conforming it to the substrate. If the radius is small, use a box cutter to makeevenly spaced cuts in the board surface base paper, which is then folded to the front side and secured
182with self-drilling tapping screws.

6.2.15 Interior Surface WorkInterior surface work involves finishing the walls, floors, andApplying putty

ceilings of a building's interior.
(1) Wallpapering the walls and the ceiling
The most common problem with wallpapering is the visibility ofthe substrate condition on the wallpaper, resulting in a poor finish.
For gypsum drywalls, the joints where the boards butt together mustbe smoothed out. Use fiber tape on the joints, apply putty, and polishto make the joints smooth and flush with the board surface. For theoutside corner, use a corner tape, apply putty, and then polished.

Corner taping the outside cornerIn the case of concrete/mortar walls, if the substrate is not treated,
it will result in poor adhesion, causing the wallpaper to lift and peel. Apply the base coat sealer, putty
the surface with a water-based seal putty or similar, and sand it smooth.
Wallpaper is applied while removing air with a brush. Corners are well pressed down with a corner
spatula, and adhered while wiping off excess glue with a sponge.
(2) Finishing the floor
There are many types of floor finishing materials, including wood, vinyl, carpet, and tile materials.
The difficult part of using any finishing material is processing the material to fit the intricately shaped
corners. For example, use scrap material with the same length as the tiles to mark the position of thecuts, or if there are round columns, use a divider to transfer the shape of the columns to the material.

183

Mark here.
Scrap
materia

Tile to be usedScrap
materia
Mark here.

Marking out a roundcolumn6.2.16 Fittings Work
Fittings work is the installation of wooden or metal fittings. Installed fittings must have specified
levels of wind pressure resistance, air tightness, water tightness, and earthquake resistance. Especiallyin Japan, where earthquakes are common, ensure that fixtures do not become dislodged or unable toopen and close due to earthquakes. This section describes the installation of wooden fittings.
Wooden fittings include kamachi-do (framed doors), flush-do (flush doors), fusuma (opaque sliding
panel), and tobusuma (wooden sliding panel), which are processed and assembled by fixture craftsmen.
When fittings are installed as sliding doors, kamoi (door lintel) and shikii (threshold) with grooves cut
for the sliding doors are installed at the doorway. Alternatively, door wheels are attached to the bottomof the fixture and a rail is attached to the threshold. When fittings are installed as swing-open doors,
hinges are used.
(1) Kamachi-do
The frame called kamachi is assembled, and a board called kagami-ita is inserted between theframes. The inside of the kamachi can also be divided by vertical and horizontal planks called kumiko.
Glass is also sometimes used instead of kagami-ita. The design could be modified to match both
Japanese and Western-style architecture.

184

(2) Flush-do
A door with a framework sandwiched with finishing panels. Flush doors are often used for interior
doors. Thick boards are used to give it a sense of heaviness when used for entrance doors.
(3) Fusuma
A wooden frame to which paper is pasted, with added rim and pull handles. It is used to separate aJapanese-style room from another Japanese-style room.
(4) Tobusuma
Fittings used to separate a Japanese-style room from a Western-style room. The Japanese-style roomside is in fusuma style, and the Western-style room side is covered with decorative veneer, etc.

6.2.17 Sash Setting Work
Sashes are fittings made of aluminum and glass. It is more airtight than wooden fittings. In the caseof a wooden structure, a frame is made on the building side for the sash to be installed so that the sash
frame will fit properly. For concrete walls, the opening is larger than the sash frame, so the installation
work proceeds as follows.
(1) Checking the installation position
Check the installation position by looking at the reference mark drawn in advance on the area to beinstalled.
(2) Temporarily fix with wedges
Temporarily fix the frame using kusabi (wedges). Using multiple wedges, the height and in/out aremeasured and fine-tuned to determine the position. A check for distortion is also conducted at thispoint.

185

(3) Weld the rebar and sash anchors

Welding method for RC structure

Rebars are embedded in the concrete walls to weld

Reinforced concrete frameSashthe sashes in place. This rebar and the weldableanchor on the sash side are welded together byEmbeddedanchorConnective
barelectric welding.
Anchor part
Welding

Mortar(4) Fill in the gaps
Fill the gap between the sash frame and the concrete wall with mortar.
(5) Glass installation
Install the glass and adjust the movement.

6.2.18 Polyurethane Spray Foam WorkWhen foaming rigid polyurethane foam, it is important to control the temperature and pressure of
the solution.
Types of individual liquid

Handling precautions

and solvents
Polyisocyanate component

Store at around 20°C, as high temperatures will alter thecomposition and low temperatures will cause solidification andprecipitation. It reacts with water to produce carbon dioxide, so
never contaminate it with water. Containers that have been
contaminated with water should not be closed, as they may burst.
Do not use open flame to heat storage containers.

Polyol component

Store at around 20°C. It is usable for the period of around threemonths. Always close the container properly, because the foam
ratio changes when the component is contaminated with water.
Since the container may have internal pressure, open it gradually to186release the pressure. Do not use open flame to heat storage
containers.
Cleaning solvent

Because of its flammability and anesthetic properties, be careful ofvapor emissions and handle in a wide open area. Open flames arestrictly prohibited.

Spray foaming machines are used for spraying work. The foaming machine is designed to achievea certain mixing ratio of the two liquid components. If the foaming machine fails and the ratio of thepolyisocyanate component becomes excessive, the foam becomes dense and brittle. Excess polyol
content results in low density and softness. Rigid polyurethane foam isself-adhesive, so it can strongly adhere to the target surface to create athermal insulation layer without the use of adhesives. However, if there ismoisture or oil on the target surface, adhesion strength will besignificantly reduced. Spraying at low temperatures also reduces
adhesion. During spraying, the thickness is checked every 4 to 5 m using

Polyurethane sprayfoam work

an urethane-atsu sokuteiki (polyurethane foam thickness gauge).

6.2.19 Waterproofing WorkIn waterproofing work, it is important to select the right materials, substrate, delivery method, andfinish according to the construction site. There are several waterproofing methods, depending on thematerials used. This section describes sheet bosui (sheet waterproofing).

187

Sheet waterproofing uses PVC or rubber sheets as the waterproofing layer. It is characterized by its
ability to efficiently waterproof large areas. There are two types of methods: secchaku koho (theadhesion method), which uses a special adhesive, and kikaiteki kotei koho (the mechanical fixing
method), in which the sheet is fixed to the waterproofed area by a machine. For both methods, thespots to watch out for are the drain (drain opening) andthe inner corners of where the flat area meets a raised
surrounding.
In the secchaku koho (the adhesion method), a special
adhesive is applied to the substrate and the sheet is fixed

Adhesion method (asphalt sheet
waterproofing)by adhesion. It is important to keep the substrate clean
and free of debris, because dirty substrate causes improper adhesion, causing accidents such as the
sheet peeling off and being blown away by strong winds. Insert sealant in the overlapping areas of the
sheets, and press the entire area well.
Kikaiteki kotei koho (the mechanical fixing method) is a method of fixing sheets using fixing discs.
Since it is less affected by the substrate, the construction period can be shortened, especially inrenovation projects. On a flat surface (flat area), lay out
the insulating sheet and fix it using kotei disc (fixingdisc). Then, spread the PVC sheet over it and join theoverlapping parts with a welding agent. Areas that havenot fully bonded are fused together with a hot air blower.

Mechanical fixing
methodThen, using a special machine called an induction heater, heat is applied to the mounting portion of
the fixing discs to integrate them with the insulation sheet. Finally, the joints of the PVC sheets aretreated with a liquid seal as secondary waterproofing.

188

6.2.20 Masonry Work
Masonry work includes the processing of stones,
building structures using stonework, and installing stones
onto structures. Specifically, the construction methods
used and the skills required differ depending on thebuilding's exterior walls, interior walls, floors, bathrooms,

Masonry work in a publicbathhouseentrances, gardens, etc. For example, in exterior wall construction, there are two types of methods:
shisshiki koho (the wet-set method), in which marble, granite, and other stone materials are placedwith mortar, etc., and kanshiki koho (dry masonry), in which the stone materials are fixed to bolt
anchors and other hardware attached to the frame. The wet-set method is more prone to postinstallation defects and requires the use of appropriate adhesives.
The use of natural stones for crazy paving for entrances requires a sense of combining various
shapes of stones, and the processing of crazy paving stones requires a skilled craftsman.
Masonry work with crazypaving stones

When handling heavy stones, take precautions to avoid accidents during transportation and possible
falling of stones. When processing stones with a grinder, handle the grinder with care and wear
protective goggles and masks to protect against dispersed dust.

189

6.2.21 Demolition Work
Demolition work is performed on structures of all sizes. There are two methods of building
demolition: block kaitai koho (floor-by-floor demolition) and happa kaitai koho (blast demolition).
Here, the floor-by-floor demolition will be explained. Demolition will begin only after confirming that
all lifeline infrastructure (electricity, telephone, fiber optic cable, cable TV, gas, water, sewage, etc.)
are shut off. For example, demolition with active gas, water, and sewage lines can lead to major
accidents. The demolition work will proceed in the following steps.
(1) Demolition of exterior areas
Remove items from around the building to make the work easier. It is necessary to confirm what is
to be demolished, as there may be items on the property that are not subject to demolition.
(2) Installation of scaffolding and soundproofing
panelsInstall scaffolding for the demolition workers. The
entire surface is covered with soundproofing panels,
soundproofing sheets, etc. to prevent noise andSoundproofing
sheet

scattering of dust from demolition.
(3) Demolition of the building interior
Remove fittings, plaster boats, sashes, and various equipment by hand. At this time, separate
recyclable material. In order to utilize resources through recycling and to curb illegal dumping ofwaste, the Construction Material Recycling Act establishes standards and penalties for demolition ofbuildings with a floor area of 80 m2 or more.
(4) Drilling holes in floors on each floor
Drill holes in the floor to allow the demolished walls and structural debris to be dropped down.
(5) Installation of support for heavy machinery
Walls and columns are dismantled by hoisting heavy equipment upward. Provide supports to190withstand the weight of heavy equipment.
(6) Demolition of walls and structure, excavation and demolition of the foundation
Because digging up foundations is an underground construction process, vibration is inevitably
generated. It is important to choose the right time of day to conduct this work.
(7) Disposal of waste, removal of debris from the ground surface, land clearing, and street
cleaning
Recyclable materials are taken to a disposal site, and the ground is cleared of debris. The
surrounding streets dirtied by the work are also cleaned and restored to their original condition.
The above is a method of demolishing from the top, but there is also a method of demolishing fromthe first floor while supporting the severed columns with jacks. Not only does it eliminate the need forsupport installation work in (5), it also allows for efficient removal and sorting of demolition materials.

191

Chapter 7: Safety during Construction Work
7.1 Fatalities in Construction WorkA variety of industrial accidents occur at construction sites. Table 7-1 shows the number of fatal
industrial accidents in the construction industry in 2021 by major accident type, based on the data
released by the Ministry of Health, Labour and Welfare. Among the various types of industrial
accidents that occur, fall from heights, accidents involving construction machinery and cranes, andcrumbling/collapsing are the three major accidents in the construction industry, accounting for 4070% of all accidents. Most of the struck-by and caught-in/between/entanglement cases in the tablebelow are accidents involving construction machinery and cranes.
The most common of the three major disasters is fall from heights that occur while working in highplaces. Aside from the three major disasters, the most common type of accident is traffic accidents that
occur while traveling on public roads. Chapter 7 describes the types and causes of accidents that occur
on construction sites, as well as countermeasures and how to be mentally prepared.

Civil engineering work

Fall fromSlipping/tripping/falling/tippingheightsoverCrashing

Flying/falling

Crumbling/Collapsing

Struck-By

CaughtIn/Between/Entanglement

Contact with
Drowning

hot/cold
objects

Exposure tohazardous
substances,

Electric shocketc.

Traffic

Traffic

accident

accident(road)(other)

Total

19

5

1

4

13

11

15

9

4

3

2

10

1

102

Tunnel construction

0

0

0

0

1

0

0

1

0

0

0

1

0

3

Bridge Construction

1

0

0

0

2

0

1

2

0

0

0

0

0

6

Road Construction

3

0

1

1

2

1

2

0

1

0

0

5

0

17

River engineering work

1

3

0

0

1

1

1

2

0

1

0

0

0

10

Erosion-control work

2

0

0

0

0

1

0

0

0

0

0

1

0

4

Harbour/coastal

0

1

0

0

0

0

1

2

0

1

0

0

1

6

Other civil engineering

9

0

0

2

4

8

8

2

3

1

2

1

0

44

71

0

0

5

15

7

6

0

6

5

2

9

0

139

23

0

0

3

5

2

0

0

3

4

0

5

0

48

Wooden-frame house construction

12

0

0

0

1

1

0

0

0

0

1

1

0

19

Building equipment installation

8

0

0

0

2

0

0

0

0

0

1

2

0

16

Other building work

28

0

0

2

7

4

6

0

3

1

0

1

0

56

20

0

0

1

3

1

6

1

1

1

4

6

0

47

Telecommunications work

4

0

0

0

1

0

2

0

1

0

2

2

0

13

Machinery and equipment installation

4

0

0

0

1

0

0

0

0

0

0

0

0

6

Other constructions

12

0

0

1

1

1

4

1

0

1

2

4

0

28

110

5

1

10

31

19

27

10

11

9

8

25

1

288

Building work
Steel frame and reinforced concrete
housesOther constructions

Construction industry subtotal

Table 7-1 Fatal Industrial Accidents in the Construction Industry in 2021 by Major Accident Type(Compiled from the Ministry of Health, Labour and Welfare's Workplace Safety Website)192

7 .1 .1Numbers of Fatalities in Construction
Table 7-2 shows the number of fatal accidents involving foreign workers in all industries in FY2020
and FY2021, as compiled by the Ministry of Health, Labour and Welfare. Table 7-3 shows that theconstruction industry has the highest numbers.
Accident Type
Fall from heights
Slipping/tripping/falling/tippingover
Crashing
Flying/falling
Crumbling/Collapsing
Struck-By
CaughtIn/Between/Entanglement
Exposuretohazardous
substances
Electric shockFire
Traffic accident (road)
Drowning
Other
Total

Number of fatalities
FY 2020
FY 2021
5
5
2

0

1
1
3
4

0
2
3
2

2

3

2

0

2
0
7
0
1
30

1
1
4
1
2
24

←Table 7-2 Occurrence of Fatal Accidents ofForeign Workers in All Industries

Industry Type
Manufacturingindustry
Constructionindustry
Other
Total

Number of fatalities
FY 2020
FY 2021
3

8

17

10

10
30

6
24

Table 7-3 Number of fatalities by industry[Tsuiraku/tenraku] (fall from heights) These are industrial accidents caused by falling from highplaces, falling down shafts during construction, or falling down a hole during excavation.
[Tento] (slipping/tripping/falling/tipping over) Industrial accidents caused by tripping over objects
or losing one's balance and falling.
[Gekitotsu] (crashing) Industrial accidents caused by a violent collision with something.
[Hirai/rakka] (flying/falling) Industrial accidents caused by loads being lifted by a crane falling, or
tools or materials falling from a high place.
[Hokai/tokai] (crumbling/collapsing) These are industrial accidents that occur when a scaffold
crumbles or a building under demolition collapses.
[Gekitotsusare] (struck-by) Industrial accidents caused by being struck by heavy machinery that is
running, by a circling bucket, etc.
[Hasamare/makikomare] (caught-in/between/entanglement) Industrial accidents caused by being193caught or entangled in machinery.
[Yugaibutsu tono sesshoku] (exposure to hazardous substances) Industrial accidents that occur
when hazardous substances, such as chemicals, come into contact with the human body.
[Kanden] (electric shock) Industrial accidents caused by electric current flowing through the body,for example, by cutting an energized wire or touching a leaking device.
[Kasai] (fire) Industrial accidents caused by being caught in a fire started by a variety of factors.
[Kotsu jiko (doro)] (traffic accident (road)) Industrial accidents that occur while commuting to andfrom construction sites, and industrial accidents that occur when a worker is involved in a generalautomobile accident during construction work next to a road.
[Obore] (drowning) Industrial accidents that occur by falling into water in places where water is apart of the work, such as oceans, rivers, and sewerage works.

7.1.2 Types of Fatal Accidents(1) Fall from heights
The most common type of fatal accidents at construction sites is death by falling from heights. In
particular, accidents tend to occur more frequently during work on
scaffolding and during the assembly and disassembly of scaffolding. In
addition, falls from slippery slate roofs occur in roofing work, and falls
from high trees occur in landscaping work. When working at heights, besure to wear and use full-harness fall protection gear. Scaffolds shouldbe equipped with middle and lower ledgers at predetermined positions forfall prevention. Also, do not pass through areas other than the designatedwork passageways. Opening should be covered with a fall prevention net.
Tripping and falling accidents also occur. Do not place unnecessary itemsin the passageways.
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(2) Collapsing
Accidents occur due to collapsing of scaffolding and buildings under construction. Both collapses
are of large, heavy objects and can lead to major accidents. Preparing a stable scaffold foundation isfundamental. There should be no gap between the mudsill and the ground, and the base fittings should
also be firmly nailed to the mudsill.
Even if the foundation is well constructed, it can collapse due to strong winds. Curing sheets andsoundproofing panels covering the scaffolding can sway and flap by strong winds, which pull on thescaffolding and cause it to collapse. In some cases, strong earthquakes are the cause of collapsing.
This is caused by human factors, as in inadequate construction by not securing wall tie anchors
properly, using fewer materials (called mabiku (thinning-out)), and other corner-cutting. In the eventof high winds, collapse can be prevented by removing some or all of the sheeting, adequately
reinforcing wall tie anchors, and periodically inspecting for loosened fasteners and other loose parts.
(3) Struck-By/Caught-In/Between
The most common accidents involving construction
machinery are caused by backhoes and cranes. Backhoes
have caused accidents such as collision between thecircling arm/bucket and a person, or a person gettingcaught between the bucket and an object.
An accident also occurred when a flagger of another vehicle failed
to notice a dump truck backing up and got caught-between.
Accidents have also occurred, such as a dump truck flicking up themudsill laid out on the site's loading ramp and hitting a flagger.
A backhoe tipping can result in fatal accidents when someone iscrushed by it. In addition, backhoe tipping accidents are more likely to occur when loading andunloading backhoes onto and off trucks, etc.
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Falling and tipping over of construction machinery canalso occur while traveling on a ramp or by falling off theshoulder of a road. Paths for construction machinery should
be wide enough to prevent the shoulder from crumbling.
Tipping over can also occur when trying to lift heavy objects
with a backhoe. Construction machinery, including but not limited to backhoes, should not be used for
purposes other than those for which they were originally intended.
Tipping over accidents can also occur with large cranes. In addition to tipping over caused by lifting
objects beyond the crane's capacity, tipping over can also occur due to improper use of outriggers to
support the vehicle body.
(4) Flying/falling
Flying and falling accidents are caused by flying or falling objects. For example, being struck by
the object carried by a crane or becoming trapped under a falling suspended load. Insufficient slinging,moving suspended loads, etc. can cause accidents. The
important thing is not to ever go below suspended loads.
Accidents have also occurred due to falling tools andcomponents to be installed.

7.1.3 Work with A High Number of Fatalities(1) Building construction
On construction sites, there is a lot of work that involves
coming and going on scaffold planks at high elevations. In
construction work, wearing full-harness fall protection gearis required when working in areas exceeding a height of 5 m.
However, accidents have occurred when the gear is worn but
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Scaffoldnot used. In addition, buildings under construction have many openings, and accidents involving
falling through these openings also occur.
(2) Housing construction
Although the number of fatal accidents in wooden-frame construction is smaller than in building
construction, nonfatal injuries are very common. In 2021, for example, there were 845 falls fromheights and 168 slipping/tripping/falling/tipping over. Death by falling from heights does not always
occur by falling from high places; it can also occur by falling from lower elevations. Carpentry work
involves working on top of beams. Falling from beams have resulted in fatal accidents. Scaffolding
can be erected around the building, but it is difficult to erect solid scaffolding for carpentry work,
which is often done in confined spaces. When working in such areas, it is important to wear a helmet,
and wear and use a safety belt.
Another falling hazard to watch out for is losing balance and falling from stepladders and ladders.
The following must be observed.
> Do not work on the top of a stepladder.
> Do not work astride a stepladder.
> Do not climb up and down stepladders or ladders while holding objects with both hands.
> Do not climb up or down a ladder without the top or bottom end of the ladder secured. Before use,check the condition of the anti-slip caps on the bottom legs.
If space is available, use stepladders with handrails, rolling towers, portable work platforms, andaerial work platforms, which pose less of a fall hazard than stepladders and ladders.
The number of fatalities and injuries, known as kire/kosure(being cut/scraped), is also significant, at 284 in 2021. The
most common cause is due to misuse of marunoko (circularsaw). For example, in the picture on the right shows a worker
with gloves, but a circular saw should never be operated with
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Example of a dangerous
way to use a circular saw

gloves on. Gloves may get entangled in the spinning blade. Also, when the wood to be cut is notproperly secured, it could kick back and cause accidents.
(3) Traffic accident (road)
Fatalities resulting from automobile accidents are a common occurrence in the construction industry
as a whole. Many traffic accidents occur while commuting to construction sites, and some traffic
accidents occur when construction vehicles are travelingon public roads. Accidents include being hit by anothervehicle while loading or unloading goods on a publicroad, or a dump truck carrying a load of surplus soil
driving too fast and overturning on a curve.

7.2 Safety Activities at Construction Sites
Construction sites are home to technicians from many job categories. Although the work performed
may seem different, experienced technicians are always mindful of some common matters. This
realizes high quality and safety. 7.2 describes common safety activities that all technicians shouldknow.

7.2.1 Cycle of Safety in Construction
By continuing the cycle of safety in construction, we can make worksites less prone to industrial
accidents. The cycle of safety in construction is to achieve the following aims.
a. Integrate construction procedures and safety.
b. Facilitate cooperation between the prime contractor and other related subcontractors.
c. Make safety and health activities a habit.
d. Be inventive in taking preemptive safety measures.

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e. Inform everyone of construction and safety requirements.
Various safety activities should be incorporated into daily operations at construction sites. To
prevent industrial accidents, it is important to set up and continue the daily cycle of safety inconstruction.
Cycle of Safety in Construction(1) Safety morning meeting beforework(To be participated by all prime contractors
and related subcontractors)(8) Safety check at theend of the workday(2) Safety meeting

Daily cycle ofsafety inconstruction(3) Inspection before
starting work

(7) Cleaning up yourassigned area(4) Guidance andsupervision during work(5) Safety patrol(6) Meeting on safe processes(1) Safety morning meeting before work
All prime contractors and related subcontractors participate in the meeting, which includes apresentation on the results of the safety patrol conducted on the previous day by the worksite managers,
instructions regarding work safety for the day's work, and radio calisthenics.
(2) Safety meeting
Discussions will be led by the foremen, by job category. The training includes reviewing the resultsof the previous day's work process, hazard prediction (KY) activities related to today's work process,and newcomer education.
(3) Inspection before starting work
Before starting work, safety inspections are conducted, including inspections of the machines andtools used, checking the work content, etc.
(4) Guidance and supervision during work
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Site supervisors (foreman, operations supervisor, etc.) provide guidance and supervision toworkers.
(5) Safety patrol
Safety patrols are conducted by the worksite manager and subcontractors, and instructions andguidance are given to each foreman, etc.
(6) Meeting on safe processes
The prime contractor and each specialty contractor will communicate and coordinate with eachother regarding work on the following day, and discuss work methods, etc.
(7) Cleaning up your assigned area
Every worker is to organize, tidy, clean, and sanitize the area he/she worked in.
(8) Safety check at the end of the workday
The prime contractor and the person in charge of specialty contractor will confirm measures toprevent fire, theft, public disaster, etc.

7.2.2 Safety and Health Education for Newcomers
Safety and health education for newcomers is provided when a business hires new workers. The
implementation of safety and health education for newcomers is required by the Ordinance on
Industrial Safety and Health.
[1] Matters related to danger or harmful effect of machines, etc., or raw materials, etc., and thoserelated to methods of handling thereof[2] Matters related to performance of safety devices, harmful substance control devices, or personal
protective equipment and matters related to methods of handling thereof[3] Matters related to operation procedures[4] Matters related to inspection at the time of commencement of work
[5] Matters related to the causes and prevention of diseases which workers are susceptible regarding200

the work[6] Matters related to keeping the workplace in order and maintenance of its sanitary conditions[7] Matters related to emergency measures and evacuation at the time of an accident[8] Beyond what is set forth in each of the preceding item, matters necessary for maintaining safety
and health related to the work

7.2.3 Newcomer education
A worker who newly enters a construction site is called a newcomer. Nearly half of all construction
site fatalities occur within one week of newly entering a site. For this reason, the Ministry of Health,Labour and Welfare has mandated newcomer education. The Guidelines for Construction Site Safety
Management by Master Employer defines the implementation standards as follows.
[Implementation of newcomer education]
In case of newly assigning any employees to work at a construction site, the related subcontractors
shall instruct their foremen, etc., to inform such workers of the following matters based on thecharacteristics of said construction site before they commence work at the site, and shall report theresults to the master employer.
[1] Conditions concerning locations where work is conducted by a mixed workforce that consistsof both the master employer's employees and the related subcontractors' employees[2] Locations that pose a danger to workers (dangerous and harmful places and no-entry zones)[3] Relationship between work processes conducted at mixed work sites[4] Evacuation methods[5] Command structure[6] Contents of the work involved and industrial accident prevention measures[7] Rules on safety and health[8] Plans that prescribe the basic policy and goals of safety and health management at the201construction site and other basic industrial accident prevention measures
The above will be implemented as follows.
(1) Before work on the day the contractor first enters the site to begin work
The person in charge from the construction company (builder), the foreman, and the health andsafety officer will conduct the training.
(2) Before work on the day a newcomer is added to the contractor's workforce
The foreman and the health and safety officer will conduct the training.
The training will take place in a conference or meeting room in the field office for about 30 minutes.

7.2.4 Safety Gear for Work
The photo below shows the safety gear for work. Full harness fall protection gear (1), helmet (2),hooks (3), and safety shoes (4) are the basic gear.

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[Full-Harness gata tsuiraku boshiyo kigu] (full-harness fall protection gear) The full-harness fall
protection gear prevents falls. From January 2, 2022, it is mandatory to wear it if the height of theworking platform exceeds 6.75 m. However, in the construction industry where falling accidents occur
frequently, the use of full-harness fall protection gear is required even when working at heights
exceeding 5 m. However, falling accidents do occur for those wearing but not using the gear, so be
sure to use it.

In addition, the following protective and safety equipment is used depending on the task.
[Hogo megane] (protective eyewear) These glasses are designed to protect the eyes from metal andwood dust, sparks, heat, smoke (including toxic gases), lasers and other harmful rays generated atconstruction sites and material processing sites. Select the best eyewear for your purpose.
[Hogo mask] (protective mask) A mask used to protect against dust and other debris. There aredisposable masks and those with replaceable filters. The Ministry of Health, Labour and Welfare(MHLW) sets the standard for masks. For example, inhaling dust from arc welding and rock cutting
operations over a long period of time can cause lung dysfunction (pneumoconiosis), so the use ofprotective masks is mandatory.
[Tebukuro] (gloves) Used to protect hands when performing machine/hand cut processing, painting
work, various types of installation work, and work involving chemical substances. However, gloves(work gloves) should not be used when using rotating blades such as circular saws, drilling machines,
chamfering machines, pipe threading machines, etc., because gloves (work gloves) can get entangled
in rotating blades and result in accidents.
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[Shield-mentsuki helmet] (welding helmet) A helmet with a shield attached to it, protecting the entire
face. Mainly used for welding work.

7.2.5 Prevention of Heat Strokes
Summer in Japan has many manatsubi (hot day) with temperatures exceeding 30°C and moshobi(extremely hot day) with temperatures exceeding 35°C. Work performed in hot temperatures can cause
the workers to have heat strokes. Heat stroke can cause
dizziness and fainting, muscle pain and stiffness, profuse
sweating, headache, mood discomfort, nausea, vomiting,fatigue, a sinking feeling, impaired consciousness,convulsions,

impairedlimb

movement,

high

body

WBGT measuring
instrument

temperature, and other symptoms that not only make it
impossible to continue working but can also cause death. The Japan Meteorological Agency calculates
and provides information on the predicted value of the Web Bulb Globe Temperature (WBGT) in eachregion. To reduce WBGT values, site managers install large fans, shading nets, dry mist systems, rest
areas, air conditioning equipment, water supply equipment, refrigerators, ice machines, drinking
watervending machines, etc. On extremely hot days, work start and end times may be moved up.
Workers should try to rest in a cool place, such as an air-conditioned rest area, during allotted breaktimes, and to drink water and consume salt before and after work. Also, wear breathable work clothes,safety vests that absorb heat easily, etc.

7.2.6 Marks Calling Attention to Work Safety
Marks with a green cross on a white background can be seen at various locations on the construction
site. This mark is called midorijuji (green cross) and is a symbol of safety and health. It is often

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designed together with the words anzen daiichi (safety first) because safety is the first and mostimportant thing on a construction site. Helmets and kyukyubako (first aid kit) containing medicine andtools for first aid in case of injuries are also marked with the green cross. Sometimes the safety andhealth flag, combining the green cross with shirojuji (white cross) which represents eisei (health), is
used.

Example of the green
cross
Examples of the safety
and health flag

7.2.7 Understanding Human Error
Mistakes caused by humans are called human errors. Human errors occur because we are human.
This includes not only mistakes caused by carelessness, but also those caused by tenuki (cutting
corners), skipping procedures that should have not been skipped. To avoid getting involved in or
causing accidents on construction sites, it is important to be conscious of possible human errors. In
addition, human errors not only cause accidents involving people, but also affect the quality of thecompleted construction as well as cause delays in the process. It is said that there are 12 different
causes of human error.
(1) Cognitive errors
It is a human error caused by assumptions. For example, the assumption that “such and such
instructions will be given in this situation” can lead to misreading the actual instructions and cues
given.

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(2) Lack of attention
It is a human error caused by lack of attention. Concentrating on one particular task can reduce
attention to one's surroundings and lead to accidents. For example, there are cases where a person isso focused on the work in front of him that he fails to notice the hole behind him and falls in.
(3) Attention lapse and diminished awarenessAttention lapse and diminished awareness can occur especially when engaged in simple andrepetitive tasks. When simple tasks are repeatedly performed, workers stop thinking about those tasks
but instead perform them unconsciously.
(4) Inadequate experience/knowledge
It is a human error caused by lack of experience and ignorance. This can result in improper use oftools, incorrect understanding of the work process, or inability to anticipate accidents that may be
associated with the work. KY activities before commencing work are an opportunity for seasoned
technicians to share their experience in predicting hazards. Workers can learn what to look out for,even when engaging in the task for the first time.
(5) Complacency
Humans tend to gain confidence through familiarity and, as a result, tend to be less careful or skip
steps compared to when they were beginners at that task. Accidents are more likely to occur when
workers become complacent and relaxed. No matter how familiar you are with the work, be sure topractice safe conduct, inspect tools before you work, check your safety equipment, and wear and checkthe fit of your safety gear.
(6) Group errors
It is a human error that occurs in groups. For example, when it seems that meeting the construction
deadline is unlikely, it is easy to for the overall atmosphere to lean towards condoning unsafe conduct.
While it is important to meet construction deadlines, the safety of people is of primary concern. In
addition, if accidents occur due to unsafe conduct, they can cause delays in the construction schedule.
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(7) Shortcuts and omissions
This is a human error caused by omitting necessary actions and procedures out of the desire to work
efficiently.
(8) Communication errors
This is a human error that occurs because the instructions are not clearly conveyed. Working without
understanding the instructions can lead to accidents and construction delays.
(9) Behavior based on situational instinct
It is an action that we unintentionally take when we are in a certain situation. Especially when people
are focus on one point, they become oblivious to their surroundings. For example, when a person isabout to fall from a stepladder, he/she would throw his/her tools in order to hang onto the stepladder.
An accident occurs if those tools hit another worker.
(10) Panic
Sudden surprises or panic can easily lead to spontaneous unsafe behavior or giving inappropriate
directions.
(11) Decline in physical and mental functions
What was possible when younger may no longer be possible due to aging. In particular, reduced
function in the legs and hips and vision impairment are difficult to notice because they occur gradually.
It is important to be aware of this so that you do not try uncomfortable actions or postures.
(12) Fatigue
Accumulated fatigue reduces alertness, and this can lead to accidents. It is important to take goodcare of your health on a daily basis, including proper sleep and nutrition.

“Have a safe day!”
207