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ABBE L6 Building Surveying study materials
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ABBE L6 Building Surveying practice questions

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Question 1Building pathology and defects

Which mechanism most commonly causes sulphate attack in clay brickwork near ground level?

  1. Soluble sulphates in the masonry reacting with cement-based mortar or render Correct answer.
  2. Frost action within the fired clay body
  3. Chloride ingress from de-icing salt
  4. Carbonation of the mortar surface

Explanation

Sulphate attack occurs when soluble sulphates, often from ground salts or the bricks themselves, react with tricalcium aluminate in cement to form expansive ettringite, disrupting the mortar. Frost, chlorides and carbonation act through different mechanisms.

Question 2Building pathology and defects

A surveyor observes fine, random hairline cracks across a plastered ceiling with no pattern following joints or edges. Which cause is most likely?

  1. Shrinkage of the plaster or backing during drying Correct answer.
  2. Overloading of the ceiling joists
  3. Subsidence of the foundations
  4. Differential movement at a structural junction

Explanation

Random hairline crazing in plaster is characteristic of drying shrinkage, where the material contracts as it cures. Structural movement and subsidence produce more directional or stepped cracking.

Question 3Building pathology and defects

Which defect is indicated by a white, powdery deposit on the face of a brick or rendered wall?

  1. Delamination
  2. Efflorescence Correct answer.
  3. Erosion
  4. Spalling

Explanation

Efflorescence is a crystalline salt deposit left on the surface as soluble salts migrate to the face and the carrier water evaporates. It is usually cosmetic but indicates moisture movement.

Question 4Building pathology and defects

What is the primary cause of frost damage to porous masonry?

  1. Thermal expansion of the clay body
  2. Ultraviolet degradation of the surface
  3. Chemical reaction between mortar and brick
  4. Water within the pores freezing and expanding Correct answer.

Explanation

Water absorbed into pores expands on freezing, generating internal pressure that can exceed the tensile strength of the material and cause spalling or disintegration. Repeated freeze-thaw cycles accelerate the damage.

Question 5Building pathology and defects

Which term describes the downward movement of a foundation caused by compressible subsoil beneath it?

  1. Heave
  2. Slip
  3. Rotation
  4. Settlement Correct answer.

Explanation

Settlement is downward movement as the ground consolidates or compresses under load. Heave is the opposite, upward movement from swelling or expansion of the subsoil.

Question 6Building pathology and defects

Timber with a moisture content consistently above which level is at significant risk of wet rot?

  1. 15 percent
  2. 35 percent
  3. 20 percent Correct answer.
  4. 10 percent

Explanation

Wet rot fungi require persistently high moisture, generally above about 20 percent moisture content in the timber, to germinate and develop. Below this threshold decay fungi cannot thrive.

Question 7Building pathology and defects

Which of the following is a classic visual indicator of possible subsidence in a masonry wall?

  1. Powdery salt deposits on the surface
  2. Diagonal stepped cracking through mortar joints Correct answer.
  3. Vertical cracking at the junction of two materials
  4. Uniform hairline crazing across the render

Explanation

Subsidence commonly produces diagonal, often stepped cracking that follows mortar joints, frequently widening towards one end. The pattern reflects differential movement of the foundation.

Question 8Building pathology and defects

What does the term 'spalling' describe in relation to brickwork?

  1. The breaking away of fragments from the face of a brick Correct answer.
  2. The growth of moss on a damp surface
  3. The separation of a render coat from its backing
  4. The leaching of lime from mortar joints

Explanation

Spalling is the loss of pieces from the surface of a brick, often caused by frost action or salt crystallisation within the brick face. It reduces the protective outer skin of the masonry.

Question 9Building pathology and defects

A surveyor finds dark staining and softening in the end of a floor joist built into a solid external wall. Which defect is most likely?

  1. Dry rot from airborne spores in a dry room
  2. Wet rot from moisture bridging into the joist end Correct answer.
  3. Wood-boring insect attack in dry timber
  4. Shrinkage of the joist as it dries

Explanation

Joist ends built into solid walls can absorb moisture from the masonry, raising timber moisture content and allowing wet rot to develop. The staining and softening are consistent with fungal decay in damp conditions.

Question 10Building pathology and defects

A wall exhibits horizontal cracking at regular intervals following the bed joints, with slight bulging. Which cause should be investigated first?

  1. Lack of lateral restraint or wall tie failure Correct answer.
  2. Sulphate attack of the mortar
  3. Efflorescence on the surface
  4. Frost damage to the brick faces

Explanation

Horizontal cracking with bulging suggests the wall is moving outward, often because of missing or corroded wall ties or inadequate lateral restraint. The pattern reflects loss of connection between leaves.

Question 11Building pathology and defects

A surveyor notes that a rendered elevation has hollow-sounding areas that move when pressed. What is the most appropriate description?

  1. Debonding Correct answer.
  2. Erosion
  3. Crazing
  4. Carbonation

Explanation

Hollow, movable areas indicate the render has lost adhesion to its backing, which is debonding. This can lead to water ingress and eventual detachment if not addressed.

Question 12Building pathology and defects

Which condition is most likely to promote condensation on the internal face of a solid wall in winter?

  1. A vapour-permeable internal finish
  2. Low internal humidity and a warm wall surface
  3. Adequate background ventilation
  4. High internal vapour pressure combined with a cold internal surface Correct answer.

Explanation

Surface condensation occurs when moist internal air meets a surface below the dew-point temperature. Solid walls are often cold internally in winter, so high internal vapour pressure readily condenses on them.

Question 13Building pathology and defects

Interstitial condensation in a wall is most likely when which combination occurs?

  1. Continuous external insulation with no thermal bridge
  2. Warm moist air meets a vapour-resistant layer on the cold side Correct answer.
  3. Cold dry air meets a vapour-open layer on the warm side
  4. A ventilated cavity with a breather membrane

Explanation

Interstitial condensation forms within the construction when water vapour diffuses towards a cold point and meets a vapour-resistant layer that prevents escape. The vapour then condenses within the fabric.

Question 14Building pathology and defects

A concrete floor slab in a basement shows a white crystalline deposit along a crack. What is the most likely explanation?

  1. Alkali-silica reaction within the aggregate
  2. Carbonation of the concrete
  3. Leaching of soluble salts through the crack with evaporating moisture Correct answer.
  4. Settlement of the slab

Explanation

Water passing through a crack can dissolve salts from the concrete or ground and deposit them at the evaporation point, producing efflorescence. The crack acts as a pathway for moisture.

Question 15Building pathology and defects

What is the principal mechanism by which corroding embedded steel causes concrete to crack and spall?

  1. The steel expands as corrosion products form, generating internal pressure Correct answer.
  2. The steel absorbs water and softens
  3. The concrete shrinks around the steel
  4. The steel contracts and pulls away from the concrete

Explanation

Corrosion products occupy a greater volume than the original steel, so expansive pressure builds up within the cover concrete. This eventually causes cracking along the reinforcement and spalling of the cover.

Question 16Building pathology and defects

A surveyor observes a horizontal damp band at low level on an internal wall with a solid floor. Which defect should be considered first?

  1. Roof leak
  2. Condensation from bathing
  3. Rising damp from the ground Correct answer.
  4. Penetrating damp from a defective gutter

Explanation

A horizontal damp band near the base of a wall, particularly with a solid floor and no effective damp-proof course, is characteristic of rising damp. Moisture rises by capillary action and is drawn to the evaporation zone.

Question 17Building pathology and defects

Which feature most reliably distinguishes dry rot from wet rot in a building survey?

  1. Softening of the timber without any mycelium
  2. The presence of white, cotton-wool growth only in wet timber
  3. The presence of orange-brown fruiting bodies with a distinctive mushroom smell and brittle cracking Correct answer.
  4. Dark staining confined to the timber surface

Explanation

Dry rot (Serpula lacrymans) is associated with distinctive fruiting bodies, rust-red spore dust, a mushroom-like odour and cuboidal cracking of the timber. It can spread through drier masonry from a moisture source.

Question 18Building pathology and defects

A retaining wall shows a diagonal crack widening at the top and leaning outward. What is the most likely cause?

  1. Lack of adequate drainage behind the wall causing increased lateral pressure Correct answer.
  2. Sulphate attack of the wall mortar
  3. Thermal expansion of the wall face
  4. Frost damage to the coping

Explanation

Retaining walls that cannot drain water behind them experience increased lateral earth and water pressure, causing overturning and diagonal cracking. The outward lean and widening crack at the top are consistent with this loading.

Question 19Building pathology and defects

What is the most likely cause of a horizontal crack along the mortar bed at the top of a long, unrestrained masonry parapet?

  1. Thermal movement of the parapet Correct answer.
  2. Sulphate attack of the coping
  3. Rising damp in the parapet
  4. Settlement of the main walls

Explanation

Long parapets exposed to sun and frost move thermally, and without movement joints the resulting expansion or contraction can fracture the mortar bed. The horizontal crack reflects the unrestrained movement.

Question 20Building pathology and defects

Why does a solid brick wall with cement-rich mortar often suffer more frost damage than one with lime mortar?

  1. Cement mortar has a lower thermal conductivity
  2. Cement mortar is more rigid and traps moisture, increasing saturation of the bricks Correct answer.
  3. Lime mortar is less permeable than cement mortar
  4. Cement mortar is more permeable and drains water away

Explanation

Hard cement mortar is less permeable and more rigid, so moisture is retained in the bricks and movement cannot be accommodated, increasing frost risk. Lime mortar is more permeable and flexible, allowing moisture to escape and movement to occur.

Question 21Building pathology and defects

A surveyor identifies a crack that is wider at the top than at the bottom on an internal wall. What does this pattern most likely indicate?

  1. Heave of the foundation beneath one end
  2. Shrinkage of the plaster
  3. Thermal expansion of the wall
  4. Settlement of the foundation beneath one end Correct answer.

Explanation

A crack wider at the top indicates that the two sides are rotating apart at the top, consistent with settlement beneath one end. The geometry of the movement determines the taper direction.

Question 22Building pathology and defects

In a two-leaf cavity wall, which defect is most directly linked to corroded wall ties?

  1. Efflorescence on the outer leaf
  2. Condensation on the inner leaf
  3. Frost spalling of the outer brick face
  4. Loss of lateral restraint leading to bulging and horizontal cracking Correct answer.

Explanation

Wall ties connect the two leaves and provide lateral restraint; when they corrode and fail, the outer leaf can move outward, causing bulging and horizontal cracking. This is a structural safety concern.

Question 23Building pathology and defects

A building surveyor is asked to distinguish between a live and a dormant wood-boring insect infestation. Which evidence is most reliable?

  1. Discolouration of the timber surface
  2. The number of exit holes per square metre
  3. Fresh frass and live larvae in the timber Correct answer.
  4. The presence of flight holes

Explanation

Fresh frass, live larvae or recent emergence indicate an active infestation. Old flight holes alone may be from a previous, now-dormant attack.

Question 24Building pathology and defects

Which condition best explains why a wall affected by rising damp may also show sulphate attack at low level?

  1. Rising damp increases the carbonation rate of the mortar
  2. Groundwater carries sulphates that react with cement in the mortar as moisture rises Correct answer.
  3. Rising damp lowers the temperature of the wall causing frost
  4. Rising damp washes sulphates out of the mortar

Explanation

Groundwater and soils can contain soluble sulphates that are carried into the masonry by rising moisture, where they react with cementitious mortar to form expansive products. This links rising damp with sulphate attack near ground level.

Question 25Building pathology and defects

A surveyor finds map cracking with a gel-like exudate on a concrete slab. Which deterioration mechanism is most likely?

  1. Sulphate attack
  2. Chloride-induced corrosion
  3. Alkali-silica reaction Correct answer.
  4. Freeze-thaw scaling

Explanation

Alkali-silica reaction produces an expansive gel that causes characteristic map cracking, often with exudate at the surface. The pattern and gel are diagnostic of ASR.

Question 26Building pathology and defects

In a traditional timber-framed roof, what is the primary function of a purlin?

  1. To support the common rafters at mid-span Correct answer.
  2. To transfer the roof load directly to the ridge board
  3. To provide a fixing for the roof covering
  4. To carry the ceiling joists and prevent wall spread

Explanation

Purlins are horizontal members that run along the roof slope to support the common rafters, reducing their effective span. They transfer loads to the principal rafters or gable walls. They do not carry ceiling joists or directly support the roof covering.

Question 27Building pathology and defects

A surveyor observes that the plaster on an internal wall is bulging and detached from the background, and tapping produces a hollow sound. Which defect is most likely present?

  1. Plaster delamination from the substrate Correct answer.
  2. Plaster blistering due to trapped moisture
  3. Sulphate attack causing expansion of the plaster
  4. Keenes cement or plasterboard dot-and-dab fixing failure

Explanation

Plaster delamination occurs when the plaster loses adhesion to its background, often due to moisture, movement, or poor initial bond, resulting in hollow sounds and bulging. Blistering is a surface phenomenon, and sulphate attack typically causes crumbling and expansion, not just hollow detachment.

Question 28Building pathology and defects

A surveyor is inspecting a concrete floor slab and notes a network of fine cracks with a white, gel-like substance exuding from them. Which deterioration mechanism is most likely responsible?

  1. Freeze-thaw cycling
  2. Sulphate attack
  3. Alkali-silica reaction Correct answer.
  4. Carbonation-induced corrosion

Explanation

Alkali-silica reaction (ASR) produces a calcium silicate hydrate gel that absorbs water and expands, causing map cracking and exuding gel. Freeze-thaw damage typically causes surface scaling, carbonation leads to reinforcement corrosion, and sulphate attack results in expansion and cracking without gel exudation.

Question 29Building pathology and defects

A surveyor is assessing a solid brick wall that shows a horizontal crack along the mortar bed at about lintel level, with the wall above appearing slightly displaced. Which defect is most likely?

  1. Subsidence due to clay shrinkage
  2. Expansion of the wall due to thermal movement
  3. Wall tie corrosion in a cavity wall
  4. Lintel failure causing localised collapse Correct answer.

Explanation

A horizontal crack at lintel level with displacement is characteristic of lintel failure, where the lintel has deflected or deteriorated, allowing the masonry above to settle. Subsidence typically causes diagonal cracking, wall tie corrosion affects cavity walls, and thermal expansion usually causes vertical or stepped cracks.

Question 30Building pathology and defects

A surveyor is investigating a Victorian house with a bay window that has pulled away from the main wall, and notes that the bay is constructed with a timber frame. Which defect is most likely responsible for the movement?

  1. Decay of the timber frame causing loss of support Correct answer.
  2. Settlement of the main building away from the bay
  3. Rotation of the bay due to inadequate foundation
  4. Expansion of the bay due to thermal movement

Explanation

Timber-framed bays rely on the timber frame for structural support; decay of the timber, often due to moisture ingress, can lead to loss of support and movement of the bay away from the main wall. Inadequate foundations would typically cause rotation or settlement from the base, and thermal expansion is unlikely to cause such separation.

Question 31Construction technology and materials

Which type of foundation is most appropriate for a lightly loaded domestic extension on stable, well-drained subsoil?

  1. Pile foundation
  2. Raft foundation
  3. Balanced basement foundation
  4. Strip foundation Correct answer.

Explanation

Strip foundations spread load over a continuous concrete strip and suit low-rise, lightly loaded buildings on competent ground. Piles and rafts are used where soil is weak or loads are heavy or uneven.

Question 32Construction technology and materials

In traditional masonry construction, what is the main function of a wall tie?

  1. To restrain the wall against ground heave
  2. To provide a damp-proof course within the cavity
  3. To bond the two leaves of a cavity wall together Correct answer.
  4. To transfer roof load to the internal leaf

Explanation

Wall ties connect the outer and inner leaves of a cavity wall so they act together and the outer leaf is restrained. They are spaced in accordance with standards and must allow any moisture to drain within the cavity.

Question 33Construction technology and materials

Which material is typically used to form a damp-proof course (DPC) in a masonry wall?

  1. Bituminous polymer sheet Correct answer.
  2. Oriented strand board
  3. Gypsum plasterboard
  4. Mineral wool batt

Explanation

A DPC must be impermeable to water, so materials such as bituminous polymer sheet, polythene or lead are used. Porous or absorbent materials would allow rising damp to pass through.

Question 34Construction technology and materials

What is the primary purpose of a lintel over an opening in a masonry wall?

  1. To provide a fixing for window frames
  2. To act as a damp-proof course across the opening
  3. To support the wall above the opening and transfer load to the abutments Correct answer.
  4. To improve the thermal performance of the reveal

Explanation

A lintel carries the masonry and other loads above an opening and transfers them to the wall on either side. It must be designed for the span and loading, with adequate bearing at each end.

Question 35Construction technology and materials

Which type of roof covering is generally unsuitable for a pitch below about 15 degrees?

  1. Standing seam metal sheet
  2. Reinforced bitumen membrane
  3. Single-ply membrane
  4. Plain clay tiles Correct answer.

Explanation

Plain clay tiles rely on overlap and pitch for weathertightness and need a steep pitch to shed water. Sheet and membrane coverings can be laid to much lower pitches because their joints are sealed.

Question 36Construction technology and materials

Which concrete constituent is primarily responsible for the mix's workability and is added in controlled amounts?

  1. Water Correct answer.
  2. Coarse aggregate
  3. Pulverised fuel ash
  4. Cement

Explanation

Water lubricates the mix and controls workability, but too much reduces strength and increases shrinkage. The water-cement ratio is a key determinant of both workability and final strength.

Question 37Construction technology and materials

In timber frame construction, what is the function of a racking panel or sheathing board?

  1. To provide the finished external appearance
  2. To carry the vertical load of upper floors
  3. To act as the primary vapour control layer
  4. To provide lateral stability against wind and racking forces Correct answer.

Explanation

Sheathing or racking panels fixed to the timber studs form a diaphragm that resists horizontal (racking) forces. Vertical loads are carried by the studs themselves, not the sheathing.

Question 38Construction technology and materials

Which masonry unit is typically used to form the inner leaf of a modern insulated cavity wall?

  1. Facing brick
  2. Natural stone ashlar
  3. Clay plain tile
  4. Aerated concrete block Correct answer.

Explanation

Aerated concrete blocks are lightweight, have good thermal and fire properties and are commonly used for the inner leaf. Facing bricks and stone are used for the external appearance.

Question 39Construction technology and materials

A designer specifies a concrete mix with a low water-cement ratio. What is the most likely primary reason?

  1. To accelerate the initial set
  2. To reduce the cost of the mix
  3. To increase compressive strength and durability Correct answer.
  4. To improve workability for placing

Explanation

Reducing the water-cement ratio lowers porosity, which raises compressive strength and improves durability. The trade-off is reduced workability, often offset with admixtures.

Question 40Construction technology and materials

Why is a cavity tray installed above an opening in a cavity wall?

  1. To collect and discharge moisture that penetrates the outer leaf Correct answer.
  2. To act as a movement joint above the opening
  3. To improve the acoustic separation between leaves
  4. To provide a structural bearing for the lintel

Explanation

A cavity tray intercepts water running down the cavity and discharges it through weep holes, preventing it reaching the inner leaf. It is particularly important at openings where the cavity is interrupted.

Question 41Construction technology and materials

A surveyor observes vertical cracking at regular intervals along a long, unreinforced masonry wall. Which is the most likely cause?

  1. Undersized lintels
  2. Rising damp at the base
  3. Absence of adequate movement joints Correct answer.
  4. Insufficient wall ties

Explanation

Long masonry walls expand and contract with temperature and moisture, so movement joints are needed to accommodate this. Without them, regular vertical cracks develop at weak points.

Question 42Construction technology and materials

Which ground condition most strongly indicates that a raft foundation should be considered?

  1. Uniform firm clay with high bearing capacity
  2. Well-graded granular fill over rock
  3. Variable or low bearing capacity across the footprint Correct answer.
  4. Rock at shallow depth

Explanation

A raft spreads load over the whole footprint and is suited to weak or variable ground where differential settlement is a risk. Where good bearing strata are near the surface, simpler foundations are usually cheaper.

Question 43Construction technology and materials

In a warm flat roof, where should the thermal insulation be positioned?

  1. On top of the ceiling plaster
  2. Between the deck and the ceiling void
  3. Below the structural deck
  4. Above the structural deck Correct answer.

Explanation

In a warm roof the insulation sits above the structural deck, keeping the deck at a temperature close to the interior and avoiding condensation within the structure. The waterproofing is laid over the insulation.

Question 44Construction technology and materials

Which property of a masonry unit most directly affects its resistance to frost damage?

  1. Its density in isolation
  2. Its colour and texture
  3. Its compressive strength alone
  4. Its water absorption and porosity Correct answer.

Explanation

Frost resistance depends on how much water a unit absorbs and how readily it can freeze and expand. Low absorption and an appropriate pore structure reduce the risk of spalling.

Question 45Construction technology and materials

A steel lintel over a wide opening is showing visible sag. Which factor is the most likely cause?

  1. A missing damp-proof course above the opening
  2. Insufficient wall ties in the outer leaf
  3. Incorrect mortar colour in the surrounding brickwork
  4. Inadequate section size for the span and load Correct answer.

Explanation

Sag indicates the lintel is overstressed or too flexible for the span and loading it carries. The section must be sized for the loads and deflection limits.

Question 46Construction technology and materials

Which type of glass provides the greatest improvement in thermal insulation for a window?

  1. Laminated single glazing
  2. Double-glazed unit with a low-emissivity coating and argon fill Correct answer.
  3. Toughened single glazing
  4. Single-glazed unit with a low-emissivity coating

Explanation

The combination of two panes, a low-emissivity coating and a heavy gas fill reduces both conductive and radiative heat loss. Single glazing, however treated, cannot match the U-value of a good double-glazed unit.

Question 47Construction technology and materials

Why is a vapour control layer normally placed on the warm side of insulation in a timber frame wall?

  1. To prevent moisture vapour reaching the cold structure and condensing Correct answer.
  2. To increase the racking strength of the frame
  3. To improve the fire resistance of the wall
  4. To act as a second damp-proof course

Explanation

The vapour control layer restricts water vapour entering the construction, so it is placed on the warm side to keep the dew point outside the frame. This reduces the risk of interstitial condensation and timber decay.

Question 48Construction technology and materials

Which mortar designation is generally most suitable for general-purpose brickwork in a sheltered, normally loaded situation?

  1. A strong 1:3 cement:sand mix
  2. Designation (iii) Correct answer.
  3. Designation (i)
  4. Designation (ii) with a high cement content

Explanation

Designation (iii) mortar offers a good balance of strength, workability and movement tolerance for general brickwork. Stronger mixes increase the risk of cracking and are reserved for more demanding situations.

Question 49Construction technology and materials

A surveyor notes that a rendered wall has cracked in a regular pattern following the blockwork joints beneath. What is the most likely explanation?

  1. Inadequate roof ventilation
  2. A blocked cavity tray
  3. Failure of the wall ties
  4. Differential movement between the render and the background Correct answer.

Explanation

Render is relatively rigid, and movement between it and the background can cause cracking that follows the underlying joints. It is often a serviceability issue rather than a structural one.

Question 50Construction technology and materials

Which construction is most likely to be specified where a basement must resist a high water table?

  1. A strip foundation with a suspended timber floor
  2. A brick-on-edge oversite with a DPC
  3. A timber-framed basement wall with a breather membrane
  4. A reinforced concrete box with a waterproofing system Correct answer.

Explanation

A reinforced concrete box provides the structural and watertight performance needed below the water table. Waterproofing is integrated with the structure to resist hydrostatic pressure.