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Sri Lanka NVQ L3 Carpenter study materials
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Sri Lanka NVQ L3 Carpenter practice questions

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Question 1Occupational Health, Safety and Environment on the Carpentry Site

On a Sri Lankan building site, which item of personal protective equipment is most important when you are using a circular saw to cut timber boards all morning?

  1. A high-visibility vest
  2. Safety goggles or a face shield Correct answer.
  3. Steel-toe rubber boots
  4. A dust mask only

Explanation

A circular saw throws out sawdust, splinters and broken blade fragments at high speed, so eye protection is the primary control for that task. Footwear and high-visibility clothing protect against other hazards but do not stop flying particles reaching the eyes. A dust mask protects the airways, not the eyes.

Question 2Occupational Health, Safety and Environment on the Carpentry Site

What is the correct way to carry a long timber plank across a busy site?

  1. Drag it along the ground behind you to keep both hands free
  2. Carry it horizontally at waist height and swing it around corners
  3. Carry it on the shoulder with the front end raised and call out at corners Correct answer.
  4. Balance it on your head so both hands can hold a ladder

Explanation

Long materials should be carried with the leading end raised so you can see and be seen, and you should warn others before turning a blind corner. This prevents the plank striking workers, scaffolding or overhead cables. Dragging or balancing the load removes control and increases the chance of injury.

Question 3Occupational Health, Safety and Environment on the Carpentry Site

A small off-cut of treated timber and some sawdust are left over at the end of the day. What is the accepted site practice?

  1. Bury them in the excavation backfill
  2. Place them in the designated waste skip for correct disposal Correct answer.
  3. Leave them in a corner for the next trade to clear
  4. Burn them in a drum behind the site to save space

Explanation

Treated timber contains preservative chemicals, so off-cuts and dust must go into the designated waste container for proper disposal rather than being burned or buried. Burning releases toxic smoke and burying contaminates soil and groundwater. Housekeeping rules also require each trade to clear its own waste.

Question 4Occupational Health, Safety and Environment on the Carpentry Site

Which statement correctly describes the purpose of a toolbox talk before starting work?

  1. It replaces the need for a written method statement
  2. It is a meeting for supervisors to plan the following month's programme
  3. It is only required when a serious accident has already happened
  4. It is a short briefing on the specific hazards and controls for that day's task Correct answer.

Explanation

A toolbox talk is a brief, task-specific briefing that reminds the crew of the hazards, safe method and controls for the work about to start. It does not replace written risk assessments or method statements, and it is held routinely, not only after incidents.

Question 5Occupational Health, Safety and Environment on the Carpentry Site

You notice a 230 V extension lead lying in a puddle on the workshop floor. What should you do first?

  1. Step over it and continue working
  2. Isolate the supply before anyone touches the lead Correct answer.
  3. Ask a colleague to test it while it is still live
  4. Pick it up quickly and move it to a dry area

Explanation

Water plus mains voltage creates a serious electric shock risk, so the supply must be isolated at the distribution board or plug before the lead is handled. Only after isolation should the lead be removed and the incident reported. Touching or testing a live lead in water endangers everyone.

Question 6Occupational Health, Safety and Environment on the Carpentry Site

Why must you never remove the riving knife from a circular saw bench?

  1. It prevents the cut timber from closing and jamming against the back of the blade Correct answer.
  2. It measures the depth of cut automatically
  3. It holds the blade guard open for faster cutting
  4. It sharpens the blade during the cut

Explanation

The riving knife keeps the saw kerf open behind the blade so the timber cannot pinch the blade and cause kickback. Removing it greatly increases the risk of the workpiece being thrown back at the operator. It has no sharpening, measuring or guard-holding function.

Question 7Occupational Health, Safety and Environment on the Carpentry Site

You are about to fix fascia boards at the edge of a two-storey roof. Which combination best controls the fall risk?

  1. Use a scaffold or mobile tower with guardrails and a harness where required Correct answer.
  2. Work from a ladder leaning against the gutter
  3. Ask a colleague to hold your belt while you lean over the edge
  4. Stand on the top rung of a step ladder and hold the board with your knees

Explanation

Work at height should be done from a platform with guardrails, such as a properly erected scaffold or mobile tower, with fall-arrest added where the risk assessment requires it. Ladders are for short-duration access, not for fixing fascia at height. Leaning over an edge or being held by a colleague gives no reliable protection.

Question 8Occupational Health, Safety and Environment on the Carpentry Site

When storing timber sheets and planks on site, which practice best prevents manual handling injuries and material damage?

  1. Stack them vertically against a wall in a walkway
  2. Pile them on the ground next to the cutting area
  3. Lean them against the scaffold standards
  4. Store them flat on level bearers in a designated rack or bay Correct answer.

Explanation

Timber should be stored flat on level bearers in a designated bay so it stays stable, dry and out of walkways. This keeps sheets from warping, prevents stacks toppling, and lets workers lift from a sensible height. Leaning material on scaffolding or blocking walkways creates collapse and trip hazards.

Question 9Occupational Health, Safety and Environment on the Carpentry Site

Fine hardwood dust is generated all day in an enclosed workshop. What is the most effective control measure?

  1. Opening one window slightly
  2. Extraction at source connected to the cutting machines Correct answer.
  3. Sweeping the dust up at the end of the shift
  4. Wearing a disposable dust mask as the only control

Explanation

Under the hierarchy of controls, local exhaust ventilation at the machine captures dust before it becomes airborne and is far more effective than personal protection alone. Hardwood dust is a respiratory sensitiser and a recognised carcinogen, so source extraction is the priority. Masks and general ventilation are secondary measures.

Question 10Occupational Health, Safety and Environment on the Carpentry Site

A worker suffers a deep cut from a hand saw. The wound is bleeding heavily. What is the correct immediate first-aid response?

  1. Apply a tourniquet immediately in every case
  2. Wash the wound with solvent to disinfect it
  3. Apply firm direct pressure with a clean dressing and get trained help Correct answer.
  4. Ask the worker to continue until the end of the shift

Explanation

Severe bleeding is controlled first by firm direct pressure with a clean dressing while trained first aiders and, if needed, emergency services are called. This is the standard first-aid priority for a heavily bleeding limb wound. Solvents damage tissue, and a tourniquet is a last resort for uncontrolled life-threatening bleeding, not a routine first step.

Question 11Occupational Health, Safety and Environment on the Carpentry Site

Which of the following is the best example of a safe system for using a nail gun on site?

  1. Keep the trigger held down while moving between fixing positions
  2. Carry the tool with your finger on the trigger for speed
  3. Test the gun by firing into the air at the start of the day
  4. Disconnect the air line before clearing jams and never point the tool at anyone Correct answer.

Explanation

Nail guns must be isolated from the air supply before jams are cleared, and the muzzle must never be pointed at a person. Sequential triggering and carrying the tool with the finger off the trigger prevent accidental discharge. Firing into the air or holding the trigger while moving are classic causes of serious puncture injuries.

Question 12Occupational Health, Safety and Environment on the Carpentry Site

You need to use a wood preservative that carries a hazard label. Which action shows correct chemical safety practice?

  1. Decant it into an unmarked water bottle for easy carrying
  2. Mix it with another solvent to make it dry faster
  3. Use it in a closed room to keep the smell away from others
  4. Read the safety data sheet and use gloves, eye protection and ventilation as specified Correct answer.

Explanation

The safety data sheet gives the hazards, exposure controls and first-aid measures for the product, and those controls must be followed. Decanting into food or drink containers causes poisoning, and mixing chemicals can produce dangerous reactions. Good ventilation is required, not a closed room.

Question 13Occupational Health, Safety and Environment on the Carpentry Site

Why is it important to keep gangways and escape routes clear on a carpentry site?

  1. It is only needed when scaffolding is being erected
  2. It allows safe movement of people and quick evacuation in an emergency Correct answer.
  3. It makes the site look tidy for visitors only
  4. It reduces the amount of material that can be stored

Explanation

Clear routes allow people to move safely with tools and materials and provide a fast escape if there is a fire or other emergency. Blocked routes are a common cause of trips and can trap workers during evacuation. Tidiness is a secondary benefit, not the main reason.

Question 14Occupational Health, Safety and Environment on the Carpentry Site

A fire starts in a pile of sawdust near a workshop heater. Which action is correct?

  1. Raise the alarm, evacuate, and use the correct extinguisher only if trained and safe Correct answer.
  2. Cover it with a timber board and leave the building
  3. Throw water on it and continue working
  4. Open all doors to let the flames out

Explanation

The first priority is to raise the alarm and get people to safety; firefighting is attempted only by trained people using the correct extinguisher and only if it is safe to do so. Sawdust fires can smoulder and flare, and water may spread burning material. Evacuation and calling the fire service protect lives.

Question 15Occupational Health, Safety and Environment on the Carpentry Site

Which of the following best describes a hazard on a carpentry site?

  1. The cost of repairing damaged equipment
  2. Anything with the potential to cause harm Correct answer.
  3. The likelihood that an accident will happen
  4. The consequence of an accident that has occurred

Explanation

A hazard is any source, situation or act with the potential to cause harm, such as an unguarded blade or a trailing cable. Risk, by contrast, combines the likelihood and severity of harm. Confusing hazard with risk leads to poor control decisions.

Question 16Occupational Health, Safety and Environment on the Carpentry Site

A worker is asked to lift a heavy hardwood beam alone. Which response is most consistent with safe manual handling?

  1. Lift it with a straight back and twisted torso to save time
  2. Assess the load and get a colleague or mechanical aid to share the lift Correct answer.
  3. Carry it at arm's length to keep it away from the body
  4. Lift it quickly with a jerking motion to overcome the weight

Explanation

Manual handling risk should be assessed first, and heavy or awkward loads should be shared with a colleague or moved with a mechanical aid. When lifting, the load is kept close to the body with a neutral back and no twisting. Jerking and arm's-length carrying greatly increase spinal loading.

Question 17Occupational Health, Safety and Environment on the Carpentry Site

A worker reports that a portable electric planer gives a slight tingle when touched. What does this most likely indicate, and what should be done?

  1. A possible earth or insulation fault; stop using it and have it tested Correct answer.
  2. Normal behaviour; continue using the tool
  3. The blade needs sharpening; keep working
  4. The cable is too long; shorten it and continue

Explanation

A tingling sensation from a tool usually signals an earth fault or damaged insulation allowing leakage current to reach the casing. The tool must be taken out of service, tagged and tested by a competent person before reuse. Continuing to use it risks a fatal shock.

Question 18Occupational Health, Safety and Environment on the Carpentry Site

Two workers disagree about whether a scaffold platform is safe to use. The platform has no toe boards and a missing guardrail section. What is the correct decision?

  1. Use only the end of the platform away from the gap
  2. Use it but tie yourself to the scaffold tube with a rope
  3. Use it carefully because the task will take only ten minutes
  4. Do not use it; report it and have it made compliant before work starts Correct answer.

Explanation

A platform missing guardrails and toe boards does not meet the standard for work at height and must not be used until it is corrected and, where required, inspected. Short duration does not make a fall less serious. Improvised rope ties and working away from the gap do not provide compliant protection.

Question 19Occupational Health, Safety and Environment on the Carpentry Site

During a risk assessment for a bench-saw task, which control should be considered first under the hierarchy of controls?

  1. Train the operator in safe use
  2. Put a warning sign on the machine
  3. Eliminate the need for the hazardous cut by using pre-cut components Correct answer.
  4. Issue hearing protection to the operator

Explanation

The hierarchy of controls starts with eliminating the hazard, for example by ordering timber pre-cut so the risky operation is not needed. Engineering and administrative controls, then PPE, come later. Signs and training are useful but rank below elimination and engineering measures.

Question 20Occupational Health, Safety and Environment on the Carpentry Site

A carpenter finds an unlabelled container of clear liquid on a bench. What is the most appropriate action?

  1. Use it as a wood cleaner to save money
  2. Pour it down the site drain to remove the risk
  3. Treat it as an unknown hazardous substance, do not use it, and report it for safe identification and disposal Correct answer.
  4. Smell it to identify whether it is solvent or water

Explanation

An unlabelled container must be treated as hazardous because its contents and hazards are unknown. It should not be used, smelled or poured away, but reported so a competent person can identify and dispose of it correctly. Pouring chemicals into drains pollutes watercourses and may be illegal.

Question 21Tools, Equipment and Machinery for Carpentry

When using a hand saw to cross-cut a piece of timber, which action best keeps the cut square and true?

  1. Start the cut with the saw at a low angle, then raise it to about 45 degrees once the kerf is established Correct answer.
  2. Saw only on the return stroke and lift the blade on the forward stroke
  3. Twist the handle slightly on the forward stroke to clear sawdust
  4. Press down heavily for the whole stroke to force the blade through the grain

Explanation

A cross-cut saw starts best with the blade held at a shallow angle so the teeth score a short kerf, then the saw is raised to roughly 45 degrees for efficient cutting. This controlled start prevents the blade from jumping and keeps the cut aligned with the marked line. Heavy pressure or twisting distorts the blade and produces a wandering, ragged cut.

Question 22Tools, Equipment and Machinery for Carpentry

What is the main purpose of the set on the teeth of a hand saw?

  1. To make the kerf wider than the saw plate so the blade does not bind Correct answer.
  2. To harden the tooth tips so they stay sharp longer
  3. To reduce the noise produced during sawing
  4. To allow the saw to cut metal as well as timber

Explanation

Set means the teeth are bent alternately left and right so the kerf is wider than the thickness of the saw plate. This clearance lets the blade move freely without binding and helps clear sawdust. Set has nothing to do with hardening the teeth or with cutting metal.

Question 23Tools, Equipment and Machinery for Carpentry

A carpenter needs to check whether a planed board face is flat along its length and across its width. Which tool is designed specifically for this check?

  1. A marking gauge
  2. A try square
  3. A steel straightedge Correct answer.
  4. A winding stick pair

Explanation

A steel straightedge is placed on edge against the surface and any gap or rocking reveals hollows or high spots, checking flatness in any direction. A try square checks squareness, a marking gauge scribes lines, and winding sticks reveal twist rather than local flatness.

Question 24Tools, Equipment and Machinery for Carpentry

When setting a marking gauge, what is the correct reference surface for the stock (fence) of the gauge?

  1. The face side or face edge that has already been prepared true Correct answer.
  2. The end grain of the board
  3. The surface that will be hidden after assembly
  4. Any convenient edge, because the gauge line is only a guide

Explanation

A marking gauge must run its stock against a surface that is known to be straight and true, normally the face side or face edge. All subsequent lines are then parallel or square to that reference. Using an unprepared edge transfers its inaccuracy to every line marked from it.

Question 25Tools, Equipment and Machinery for Carpentry

Which plane is the correct choice for trimming the end grain of a door stile to a fine finish?

  1. A low-angle block plane used with a fine cut Correct answer.
  2. A router plane
  3. A rebate plane
  4. A jack plane with a heavily cambered iron

Explanation

A low-angle block plane is held in one hand and its low cutting angle suits end grain, where it slices rather than lifts the fibres. A fine cut and sharp iron give a clean finish on the end of a stile. Jack planes, router planes and rebate planes are intended for other work.

Question 26Tools, Equipment and Machinery for Carpentry

What is the function of the cap iron (chip breaker) fitted on a bench plane?

  1. It adjusts the depth of cut without moving the iron
  2. It stiffens the cutting iron and breaks chips so the shaving curls away cleanly Correct answer.
  3. It protects the cutting edge when the plane is set down
  4. It holds the cutting iron firmly against the frog

Explanation

The cap iron is screwed on top of the cutting iron close to the edge; it stiffens the assembly and turns the shaving so it breaks and clears the mouth. Setting it close to the edge reduces tear-out on difficult grain. It does not clamp the iron to the frog or control depth of cut.

Question 27Tools, Equipment and Machinery for Carpentry

Which chisel is most suitable for cleaning out the bottom corners of a deep mortise?

  1. A paring chisel
  2. A mortise chisel Correct answer.
  3. A gouge
  4. A bevel-edge firmer chisel

Explanation

A mortise chisel has a thick, strong blade and a square section that withstands levering when waste is removed from a deep mortise. Its parallel sides also help keep the walls of the mortise straight. The other chisels are lighter or shaped for different tasks.

Question 28Tools, Equipment and Machinery for Carpentry

Before using a chisel, a carpenter checks that the handle is tight on the tang. Why is this important?

  1. A loose handle can split or fly off under mallet blows and cause injury Correct answer.
  2. A loose handle prevents the chisel from being sharpened
  3. A loose handle changes the bevel angle of the cutting edge
  4. A loose handle makes the chisel cut faster

Explanation

The tang is driven into the handle, and if the fit loosens the handle can split or come off during mallet work. A flying handle is a serious injury risk and the tool cannot be controlled. Handle tightness does not affect bevel angle or sharpening.

Question 29Tools, Equipment and Machinery for Carpentry

Which hammer is normally used to drive panel pins when fixing mouldings, because its light head gives control?

  1. A club hammer
  2. A pin hammer Correct answer.
  3. A cross-pein hammer
  4. A claw hammer

Explanation

A pin hammer is small and light, which allows short, controlled taps on thin panel pins without bruising the moulding. A claw hammer is heavier and better for nails, a cross-pein is used in metalwork, and a club hammer is far too heavy for pins.

Question 30Tools, Equipment and Machinery for Carpentry

When using a cordless circular saw to cut a sheet of plywood, which practice best reduces the risk of kickback?

  1. Hold the sheet with one hand while cutting with the other
  2. Support the sheet firmly on both sides of the cut line and keep the base plate flat on the work Correct answer.
  3. Cut with the blade set as deep as possible through the sheet
  4. Let the blade stop completely before lifting the saw

Explanation

Kickback happens when the blade binds because the material pinches or the base plate lifts. Firm support on both sides of the cut and keeping the base flat prevent the sheet from closing on the blade. Correct depth setting also helps, but support is the primary control.

Question 31Tools, Equipment and Machinery for Carpentry

What does the riving knife on a circular saw bench (table saw) do?

  1. It holds the timber down against the table
  2. It prevents the kerf from closing behind the blade and causing kickback Correct answer.
  3. It guides the timber against the fence at the correct angle
  4. It measures the width of the cut

Explanation

The riving knife sits directly behind the blade in line with the cut and is slightly thinner than the kerf. It stops the cut timber closing onto the rising teeth, which is a main cause of kickback. It does not guide, hold down or measure.

Question 32Tools, Equipment and Machinery for Carpentry

In a workshop with a 230 V supply, which device is fitted to protect the operator from electric shock if a portable power tool develops a fault?

  1. A residual current device (RCD) Correct answer.
  2. A circuit breaker sized for lighting
  3. A step-down transformer
  4. A voltage stabiliser

Explanation

A residual current device detects current leaking to earth, for example through a damaged tool or a person, and trips the supply quickly. It is the standard protection for portable tools on site. Transformers change voltage, stabilisers smooth voltage, and lighting breakers protect cables, not people.

Question 33Tools, Equipment and Machinery for Carpentry

Why must the guard on a portable angle grinder never be removed when cutting timber with a cutting disc?

  1. The guard contains fragments if the disc shatters and deflects sparks and dust Correct answer.
  2. The guard increases the cutting speed of the disc
  3. The guard balances the machine so it runs smoothly
  4. The guard keeps the disc cool during cutting

Explanation

An abrasive disc can shatter at high speed, and the guard is designed to contain the fragments and direct debris away from the operator. Removing it exposes the user to serious injury. The guard has no effect on balance, speed or cooling.

Question 34Tools, Equipment and Machinery for Carpentry

A carpenter is drilling 10 mm holes in hardwood with a portable electric drill and the bit keeps overheating. What is the most likely cause?

  1. The drill is running too slowly
  2. The drill is fitted with an RCD
  3. The bit is blunt or the feed pressure is too light, causing rubbing instead of cutting Correct answer.
  4. The chuck is too tight

Explanation

A blunt bit or insufficient feed pressure makes the cutting edges rub rather than cut, generating heat in the hole. Sharpening or replacing the bit and applying steady pressure restores cutting. Chuck tightness and RCD protection do not cause overheating.

Question 35Tools, Equipment and Machinery for Carpentry

What is the correct way to store a hand plane between uses to protect the cutting edge?

  1. Hang it by the front knob with the iron extended
  2. Store it in a bucket of water to keep the iron cool
  3. Rest it on its sole with the iron extended
  4. Lay it on its side or set it on a wooden block with the iron retracted Correct answer.

Explanation

Laying a plane on its side or on a wooden block, or retracting the iron, prevents the sharp edge from contacting hard surfaces. The edge is fragile and a small nick means regrinding. Resting on the sole with the iron out risks damage and rust from damp surfaces.

Question 36Tools, Equipment and Machinery for Carpentry

A carpenter notices a fine crack running from the corner of a wooden plane body towards the mouth. What is the safest course of action?

  1. Glue the crack and continue heavy work immediately
  2. Withdraw the plane from use and repair or replace the body, because the wedge pressure can split it completely Correct answer.
  3. Ignore it because cracks in wooden planes do not affect accuracy
  4. Continue using it but tap the wedge harder to hold the iron

Explanation

The wedge exerts wedging pressure that can propagate a crack and cause the body to split suddenly, throwing the iron or spoiling the work. The plane should be withdrawn and the body repaired or replaced before further use. Ignoring the crack or adding pressure increases the risk.

Question 37Tools, Equipment and Machinery for Carpentry

Which tool is used to cut the shoulder of a tenon accurately across the grain after the cheek cuts have been made?

  1. A coping saw
  2. A dovetail saw used only for fine curves
  3. A rip saw
  4. A tenon saw, using the shoulder line as a guide Correct answer.

Explanation

A tenon saw has a stiff back and fine cross-cut teeth that allow a straight, controlled cut along the shoulder line. The back stiffens the blade so it stays in the marked line. A coping saw is for curves, and a rip saw is too coarse for an accurate shoulder.

Question 38Tools, Equipment and Machinery for Carpentry

When sharpening a chisel on an oilstone, why is the bevel kept flat on the stone during honing?

  1. To make the stone wear evenly
  2. To remove more metal quickly
  3. To prevent the handle from loosening
  4. To keep the bevel angle constant and produce a straight, sharp edge Correct answer.

Explanation

Holding the bevel flat on the stone maintains the ground angle and produces a straight edge across the full width. Rocking the blade rounds the bevel and gives a curved, weak edge. Even stone wear and handle tightness are not the purpose of the technique.

Question 39Tools, Equipment and Machinery for Carpentry

A carpenter must cut a large number of identical rebates in softwood door frames in the workshop. Which machine is the most efficient and accurate choice?

  1. A hand-held router used freehand
  2. A scroll saw
  3. A band saw
  4. A spindle moulder with a rebate cutter and a power feed Correct answer.

Explanation

A spindle moulder with a rebate cutter and power feed gives a repeatable, accurate rebate at production speed with the work held safely. Freehand routing is slower and less consistent, while band and scroll saws cannot produce a clean rebate.

Question 40Tools, Equipment and Machinery for Carpentry

What is the correct procedure before changing the blade on a mitre saw?

  1. Leave the machine running at low speed while loosening the bolt
  2. Switch off at the trigger only and change the blade immediately
  3. Switch off, unplug or remove the battery, and wait for the blade to stop Correct answer.
  4. Ask a second person to hold the blade while the bolt is loosened

Explanation

The machine must be isolated from the supply, either unplugged or with the battery removed, and the blade allowed to come to a complete stop before any work near it. This prevents accidental start-up and contact with a moving blade. Relying on the trigger or on another person does not provide safe isolation.

Question 41Materials, Timber Technology and Material Selection

In Sri Lankan timber grading, a piece of timber showing a live knot that is sound, tight and small is usually classified as which type of defect?

  1. A serious structural defect that requires rejection of the piece
  2. A seasoning fault caused by too-rapid drying
  3. A sign of fungal decay in the heartwood
  4. A permissible natural feature that has limited effect on strength Correct answer.

Explanation

Sound, tight knots are natural growth features of timber and are accepted within limits in most structural grades because the surrounding grain remains continuous. Only large, loose or dead knots that interrupt the grain significantly reduce the effective section and are treated as serious defects.

Question 42Materials, Timber Technology and Material Selection

Which property makes coconut timber (kitul/coconut palm) attractive as a substitute for conventional hardwood in Sri Lankan furniture and joinery?

  1. It can be bent easily without steaming
  2. It has a hard, dense outer zone with an attractive grain pattern Correct answer.
  3. It shrinks very little during drying compared with other species
  4. It is naturally resistant to termites in all its zones

Explanation

Coconut palm timber has a very dense, hard outer portion and a softer inner portion, and the hard zone takes a good finish and shows an attractive figure. This makes it useful for furniture and joinery where a durable, decorative surface is needed.

Question 43Materials, Timber Technology and Material Selection

A carpenter needs timber for roof rafters in a humid coastal area of Sri Lanka. Which selection best matches the requirement?

  1. Well-seasoned, treated structural timber of adequate grade and strength class Correct answer.
  2. Decorative veneered board chosen for its surface appearance
  3. Thin plywood offcuts glued together to make up the required depth
  4. Unseasoned sawn timber straight from the mill to save time

Explanation

Rafters are structural members carrying roof loads, so they must be of adequate strength grade, properly seasoned to limit movement, and treated for durability in a humid coastal environment. Appearance and cost savings cannot override structural and durability requirements.

Question 44Materials, Timber Technology and Material Selection

What is the main purpose of stacking sawn timber with spacers (stickers) during air seasoning?

  1. To speed drying by trapping warm air between the boards
  2. To press the boards flat and remove all internal stresses
  3. To protect the boards from rain and direct sunlight
  4. To allow air to circulate evenly between boards so moisture escapes uniformly Correct answer.

Explanation

Stickers create gaps between boards so air can move across both faces and moisture can leave the timber evenly, which reduces checking and distortion. The stack is usually also covered and weighted, but those are separate measures.

Question 45Materials, Timber Technology and Material Selection

Which statement correctly describes the difference between heartwood and sapwood?

  1. Sapwood and heartwood differ only in colour and never in durability
  2. Sapwood is the darker inner wood and is more durable than heartwood
  3. Heartwood is the pale outer zone that conducts sap upward
  4. Heartwood is the older, darker inner wood and is usually more durable than sapwood Correct answer.

Explanation

Heartwood is the inner, older wood that no longer conducts sap and has often accumulated extractives that increase durability and darken its colour. Sapwood is the outer, living zone that conducts sap and is generally less durable and more permeable.

Question 46Materials, Timber Technology and Material Selection

A board has cupped across its width after drying. Which is the most likely cause?

  1. Unequal drying between the two faces of the board Correct answer.
  2. The board was stored flat on a solid floor
  3. The board was too thin to dry
  4. The board was cut exactly on the pith

Explanation

Cupping occurs when one face dries faster than the other, so the faces shrink unequally and the board curves across its width. Equal drying on both faces is why stickers and good air circulation are used.

Question 47Materials, Timber Technology and Material Selection

Which preservative treatment method is most suitable for timber that will be buried in the ground or exposed to high termite risk?

  1. Wrapping the timber in polythene sheeting
  2. Dipping the ends of the timber only
  3. Pressure impregnation with a suitable preservative Correct answer.
  4. Brushing the surface with oil-based paint

Explanation

Pressure impregnation forces preservative deep into the timber so that the treated zone resists termites and decay even when the surface is damaged or in contact with soil. Surface methods only treat the outer skin and are inadequate for high-risk in-ground use.

Question 48Materials, Timber Technology and Material Selection

Which adhesive is generally preferred for making a load-bearing structural timber joint in a workshop?

  1. A general-purpose office glue stick
  2. A hot-melt glue applied with a hand gun
  3. A solvent-based contact adhesive
  4. A resorcinol-formaldehyde or similar structural-grade cold-setting adhesive Correct answer.

Explanation

Structural joints need adhesives that develop high strength, resist moisture and creep, and are specified for load-bearing use, such as resorcinol-formaldehyde. General-purpose and hot-melt adhesives lack the durability and creep resistance required.

Question 49Materials, Timber Technology and Material Selection

What does the equilibrium moisture content of timber depend on?

  1. The species of timber only
  2. The length of the piece being sawn
  3. The colour of the timber surface
  4. The relative humidity and temperature of the surrounding air Correct answer.

Explanation

Timber gains or loses moisture until it reaches equilibrium with the surrounding air, so equilibrium moisture content is governed by relative humidity and temperature. Species affects the rate and amount of movement but not the equilibrium condition itself.

Question 50Materials, Timber Technology and Material Selection

A carpenter is fixing solid timber floorboards in a room and wants to reduce the risk of gaps opening as the boards dry. Which precaution is most appropriate?

  1. Install boards at a moisture content close to the expected in-service moisture content Correct answer.
  2. Install boards tight against each other with no allowance for movement
  3. Install boards straight after delivery regardless of moisture content
  4. Soak the boards in water before fixing

Explanation

Floorboards should be conditioned to a moisture content near that expected in service so that subsequent shrinkage or swelling is small. If boards are installed much wetter or drier than service conditions, gaps or buckling will develop.