Materials, Building Physics and Constructability

Introduction

Building construction is the controlled transformation of materials into safe, durable and usable spaces. Material selection cannot be separated from building physics or from the practical conditions of construction. A concrete mix may possess high compressive strength but perform poorly if it is inadequately compacted. A wall may have a low calculated thermal transmittance but still suffer condensation because of thermal bridges or uncontrolled air leakage. A timber component may be structurally efficient, yet vulnerable to decay if moisture is not controlled. Constructability links design intent with the sequence, skills, equipment, tolerances and temporary works required to produce the building safely and economically.

This chapter examines concrete, masonry, metals, timber, glass, polymers and composites in relation to strength, durability, fire, moisture, thermal and acoustic performance. It then develops principles for constructability and life-cycle decision-making. The emphasis is not on memorizing isolated material properties, but on understanding how materials behave as parts of assemblies exposed to loads, heat, water, air, sound, fire and time.

Learning objectives

By the end of this chapter, students should be able to:

1. Relate the principal properties of common construction materials to structural and environmental performance.
2. Explain how moisture, heat, sound and fire move through building assemblies.
3. Distinguish material properties from system performance and identify important interfaces.
4. Select materials using durability, constructability, maintenance and life-cycle criteria.
5. Analyze a practical construction problem and recommend a technically defensible solution.
6. Recognize the importance of standards, workmanship, documentation, safety and ethical professional judgment.

1. Material behavior as a system of properties

A material is characterized by properties, but a building is characterized by performance. Properties include density, stiffness, strength, permeability, thermal conductivity, fire behavior and chemical stability. Performance depends additionally on geometry, connections, workmanship, exposure, maintenance and interaction with neighboring materials.

1.1 Mechanical properties

Strength is the capacity to resist a specified stress without unacceptable failure. Compression, tension, shear, bending and impact produce different responses. Concrete and masonry are generally strong in compression but weak in tension. Steel is strong in both tension and compression, although slender steel members may buckle. Timber is directional: its properties parallel to the grain differ substantially from those perpendicular to the grain.

Stiffness describes resistance to deformation. Young’s modulus, E, relates normal stress to strain within the linear elastic range:

where σ is normal stress in pascals (Pa) and ε is dimensionless strain. The expression applies to a linearly elastic, homogeneous material under an appropriate uniaxial loading condition. A high strength material is not necessarily highly stiff; strength concerns failure, whereas stiffness concerns deformation.

For a uniformly loaded axially loaded member, the elastic extension is:

where δ is extension (m), P is axial force (N), L is member length (m), A is cross-sectional area (m²), and E is Young’s modulus (Pa). This equation assumes a prismatic member, concentric axial loading, small deformation and elastic behavior.

Ductility is the capacity to undergo significant deformation before fracture. Ductile steel can redistribute stresses and provide warning through yielding. Brittle materials such as glass and unreinforced masonry may fail with little visible deformation. Toughness is the capacity to absorb energy before fracture, while hardness concerns resistance to indentation or abrasion.

1.2 Durability and compatibility

Durability is the ability to maintain required performance over the intended service life under stated exposure conditions. Deterioration mechanisms include corrosion, carbonation, chloride ingress, freeze–thaw action, sulfate attack, alkali–silica reaction, fungal decay, ultraviolet degradation, thermal cycling and fatigue.

Compatibility must be assessed at interfaces. Dissimilar metals can form galvanic cells in the presence of an electrolyte. Timber movement can stress rigid finishes. Impermeable coatings can trap moisture in masonry. Concrete shrinkage can crack rigid partitions. Sealants must remain compatible with substrates and expected movement. A successful specification therefore states not only the material but also preparation, installation, jointing, protection and inspection requirements.

2. Concrete and masonry

2.1 Concrete

Concrete is a composite of cement paste, water, fine aggregate and coarse aggregate, commonly supplemented by mineral additions and chemical admixtures. Hydration produces binding compounds that develop strength over time. Concrete is economical, fire resistant in many applications and adaptable to complex forms, but it is heavy, relatively weak in tension and susceptible to cracking.

The water–cement ratio strongly influences porosity and strength. A lower ratio generally reduces capillary pores and improves strength and durability, provided that the mix remains workable and is properly compacted. Excess water increases bleeding, porosity and drying shrinkage. Workability should be achieved through mix design and suitable admixtures rather than uncontrolled water addition on site.

Reinforced concrete combines concrete’s compressive capacity with steel reinforcement’s tensile capacity. Bond transfers stress between the materials. Reinforcement cover protects steel from fire and corrosion, but cover must be selected and constructed according to exposure, fire and code requirements. Insufficient cover, cracking or chloride-contaminated materials can initiate corrosion, causing rust expansion, cracking and spalling.

Fresh concrete requires control of batching, transport, placement, vibration, finishing and curing. Curing maintains moisture and temperature conditions needed for hydration. Poor curing may produce a weak, porous surface even when the designed mix is adequate. Construction joints should be located deliberately; cold joints formed by unplanned delays may reduce watertightness and structural continuity.

Concrete’s principal fire advantage is non-combustibility and low thermal conductivity relative to metals. Nevertheless, rapid heating can cause explosive spalling, especially in dense or high-strength concrete with internal moisture. Fire performance depends on member size, reinforcement cover, moisture, restraint and the specified fire-resistance period.

2.2 Masonry

Masonry uses units such as clay brick, concrete block or natural stone, joined by mortar or, in some systems, thin-bed adhesive. Its performance depends on unit properties, mortar, joint geometry, workmanship, reinforcement, restraint and exposure. Masonry can provide enclosure, fire resistance, thermal mass and acoustic separation.

Unreinforced masonry is efficient in compression but vulnerable to tensile and lateral actions. Cracking can result from foundation movement, thermal movement, moisture expansion, drying shrinkage or differential movement between masonry and structural frames. Movement joints, reinforcement and appropriate ties control these effects.

Masonry walls may be load-bearing, non-load-bearing, veneer or cavity-wall systems. A cavity can improve rain control by separating the outer weather layer from the inner structural or insulating layer. Weep openings and flashings must be continuous and unobstructed so that water entering the cavity can drain outward.

Mortar should not simply be made as strong as possible. Excessively strong mortar may be less accommodating of movement and can damage softer masonry units. The mortar’s strength, permeability and deformability should be compatible with the masonry and exposure.

3. Metals

Structural steel has high strength-to-weight ratio, predictable manufactured properties, rapid prefabrication and useful ductility. It is used in frames, trusses, reinforcement, cladding and fixings. Aluminum is lighter and naturally develops an oxide film, but it has lower stiffness than steel and loses strength significantly when heated. Copper and zinc are widely used for services and roofing because of corrosion resistance and workability.

Steel design must consider yielding, fracture, fatigue, corrosion and buckling. A compression member can fail by instability before the material reaches its compressive strength. Connections are often the controlling components and require attention to bolts, welds, eccentricity, tolerances and inspection.

Steel rapidly loses strength and stiffness at elevated temperature. Fire protection may be provided by concrete encasement, sprayed protection, intumescent coatings or board systems. Protection must be continuous around connections and maintained after later alterations.

Corrosion requires an electrolyte, usually water containing dissolved salts, and an electrochemical potential. Control measures include appropriate alloy selection, drainage, protective coatings, galvanizing, cathodic methods and avoiding water traps. Coating systems require surface preparation and specified dry-film thickness; a coating is not a substitute for good detailing.

Where dissimilar metals meet, electrical isolation or compatible materials may be needed. For example, direct contact between certain aluminum components and copper-containing drainage can accelerate corrosion in wet conditions. Designers should also account for thermal expansion, which can generate movement in long metal cladding systems.

4. Timber

Timber is a renewable, relatively lightweight material with a high strength-to-weight ratio and low embodied energy in many supply chains. It is anisotropic: strength and stiffness parallel to grain are generally much greater than perpendicular to grain. Knots, slope of grain, checks, splits, density and moisture content influence structural performance.

Moisture content affects dimensions and durability. Timber generally shrinks as it dries below the fiber saturation range and swells as it gains moisture. Repeated wetting and drying can cause distortion and cracking. Fungal decay requires moisture, oxygen, suitable temperature and a food source; keeping timber dry is usually the most effective control.

Good timber construction separates timber from ground moisture, provides roof overhangs and flashings, ventilates concealed spaces, protects end grain and avoids water traps. Preservative treatment may be necessary, but treatment does not correct poor detailing. Termite risk, fire exposure and local biological hazards must be addressed.

Timber is combustible, but large timber members may form a protective char layer that slows heating of the remaining section. Fire design must account for charring, connections, concealed cavities, linings and the required period of resistance. Adhesives in engineered wood products must be suitable for the intended moisture and fire conditions.

Engineered products such as glued-laminated timber, laminated veneer lumber and cross-laminated timber improve dimensional consistency and enable larger spans. Their behavior remains dependent on adhesive performance, panel joints, connection detailing, moisture protection and construction-stage exposure.

5. Glass, polymers and composites

5.1 Glass

Glass is hard, transparent and chemically stable in many environments, but it is brittle and sensitive to flaws. Its tensile capacity is governed by surface defects, edge quality, loading duration and stress concentrations. Safety glazing, including tempered and laminated glass, reduces injury risk in hazardous locations. Tempered glass has increased surface compression but can fragment into small pieces after breakage. Laminated glass retains fragments through an interlayer and can provide post-breakage retention.

Glass systems must accommodate thermal expansion, frame movement, wind pressure, impact, differential deflection and sealant movement. Glass should not bear directly on hard contaminants or be tightly trapped in frames. Drainage, setting blocks and edge clearances are essential.

Glazing strongly affects heat gain, heat loss, daylight and acoustics. Double or triple glazing, low-emissivity coatings, gas fills and solar-control coatings can improve energy performance, but thermal bridges at frames and perimeter seals may reduce whole-window performance. Acoustic performance depends on pane thickness, air spaces, laminated interlayers, frame leakage and flanking paths.

5.2 Polymers

Polymers include plastics, elastomers, membranes, sealants, insulation products, pipes and coatings. They are lightweight, corrosion resistant and easily formed. Their limitations include creep, thermal expansion, ultraviolet degradation, solvent sensitivity, smoke generation and fire behavior.

Thermoplastics soften when heated and can often be reshaped; thermosets cure into more stable networks but may char or degrade rather than melt. Elastomers accommodate movement but can lose properties through aging. Selection must consider temperature, chemical exposure, joint movement, vapor permeability, fire classification and expected service life.

Polymer membranes are valuable for waterproofing and air control, but laps, penetrations, terminations and substrate preparation often govern performance. A membrane that is theoretically impermeable may fail because of punctures or discontinuous detailing.

5.3 Composites

A composite combines two or more distinct constituents, commonly a matrix and reinforcement. Reinforced concrete, fiber-reinforced polymers, sandwich panels and engineered timber are examples. Composites can provide high stiffness or strength at low mass, but their properties may be directional and their failure modes complex.

Designers must consider delamination, moisture ingress, differential thermal expansion, fire performance, connection strength and inspection. Mechanical connections may crush or split the matrix, while bonded connections require controlled surface preparation and curing. Composite systems should not be selected solely from headline strength-to-weight values.

6. Building physics

Building physics examines interactions between the building, its occupants and the environment. The principal flows are heat, moisture, air, sound and fire. These flows are coupled: air leakage can transport moisture; moisture changes thermal conductivity; thermal bridges can cause condensation; fire and smoke move through concealed air paths.

6.1 Heat transfer and thermal performance

Heat moves by conduction, convection and radiation. For one-dimensional steady conduction through a uniform layer:

where q is heat-transfer rate (W), k is thermal conductivity (W/(m·K)), A is area (m²), and dT/dx is the temperature gradient (K/m). The negative sign indicates heat flows down the temperature gradient. For a plane layer of thickness L with constant properties:

where Q̇ is heat-transfer rate (W), and T₁ and T₂ are the temperatures of the two faces (K or °C difference). This simplified equation assumes steady, one-dimensional conduction and negligible contact resistance.

Thermal resistance for a homogeneous layer is:

with units m²·K/W. For a series assembly, surface and layer resistances are added:

The thermal transmittance, or U-value, is:

where U has units W/(m²·K). These equations apply to simplified one-dimensional areas. Real assemblies require correction for thermal bridges, fasteners, repeating bridges, air films and two- or three-dimensional heat flow.

Worked example. A wall layer is 0.12 m thick and has thermal conductivity 0.040 W/(m·K). Its resistance is:

R = 0.12 ÷ 0.040 = 3.0 m²·K/W.

If surface resistances and other layers provide an additional 0.50 m²·K/W, total resistance is 3.50 m²·K/W and:

U = 1 ÷ 3.50 ≈ 0.286 W/(m²·K).

This is the idealized transmittance of the stated assembly, not necessarily the whole-wall value.

Thermal mass is the capacity of a material to store heat. Dense concrete and masonry can moderate indoor temperature swings when exposed to the interior and combined with appropriate ventilation and solar control. Thermal mass does not automatically reduce annual energy use; its benefit depends on climate, occupancy, control strategy and night-time heat rejection.

6.2 Moisture and condensation

Moisture enters buildings through bulk rain, capillary suction, vapor diffusion, air transport and plumbing leaks. Control requires a continuous water-shedding layer, drainage plane, capillary break, air-control layer and, where needed, vapor-control layer. Their location depends on climate and assembly design.

Condensation occurs when a surface or internal plane falls below the dew-point temperature of adjacent air. The dew point is determined by air temperature and relative humidity. Vapor diffusion is often slower than moisture transport through air leakage; therefore, continuity of the air barrier is a central moisture-control strategy.

Masonry and concrete can absorb and redistribute water. Drying potential is therefore important. Assemblies should be designed so that incidental moisture can drain or dry without damaging insulation, corrosion-sensitive components or finishes. Site storage and temporary protection are part of moisture design, particularly for timber, gypsum products, insulation and interior finishes.

6.3 Acoustics

Sound reaches a room through airborne transmission, impact transmission and flanking paths. Mass, separation, damping, airtightness and absorption all matter. A heavy, airtight wall may resist airborne sound, but a gap around a service penetration can substantially reduce performance. Resilient connections and isolated floor layers reduce impact transmission.

Sound absorption within a room reduces reverberation but does not necessarily prevent sound transmission between rooms. Porous absorbers are most effective when appropriately located and protected. Acoustic design must consider the complete system, including doors, windows, ducts, junctions and structural paths.

6.4 Fire and smoke

Fire performance includes ignition, flame spread, heat release, smoke production, structural resistance, compartmentation and safe evacuation. Non-combustible does not mean immune to heat-induced failure, and a fire-rated assembly is only effective when penetrations, joints and interfaces are treated equivalently.

Compartment walls, floors, fire doors, dampers and service seals limit fire and smoke spread. Construction sequencing matters: temporary openings and incomplete seals can create hidden routes. Fire-stopping should be installed by competent personnel, documented and protected from later damage.

7. Constructability

Constructability is the extent to which a design facilitates efficient, safe, quality-controlled construction using available resources. It begins during concept design rather than after drawings are complete.

Important constructability questions include:

• Can components be transported, lifted and safely positioned?
• Are tolerances realistic and coordinated between trades?
• Is the construction sequence feasible, including temporary stability?
• Can workers access joints, fixings, inspections and maintenance points?
• Are materials available, compatible and protected during storage?
• Can the design be built without excessive rework, hazardous exposure or waste?
• Are interfaces and responsibilities unambiguously documented?

Design for manufacture and assembly can shift work from variable site conditions to controlled factory environments. Prefabrication may improve quality and reduce site labor, but it introduces transport limits, lifting requirements, connection tolerances and logistics risks. Modular coordination reduces cutting and adaptation, but modules must align with structure, services, fire compartments and access routes.

Tolerance management is essential. If a structural frame, façade and interior partition each have independent tolerances, their combined variation may exceed the available clearance. Designers should define reference lines, permitted deviations, adjustment zones and inspection procedures. Robust details provide controlled adjustment rather than relying on field improvisation.

The construction sequence must also be structurally valid. A completed building may be stable while an incomplete frame, unbraced panel or partially connected truss is unstable. Temporary bracing, lifting points, weather protection and temporary drainage should be designed and communicated.

8. Life-cycle principles and professional decision-making

A life-cycle approach evaluates impacts and costs from raw material extraction through manufacture, construction, use, maintenance, replacement and end-of-life. Initial price alone is an inadequate selection criterion. A cheaper material may require frequent coating, replacement or energy use; a more expensive durable component may produce lower total cost and disruption.

Life-cycle cost can be represented conceptually as:

where LCC is life-cycle cost in present monetary units, C₀ is initial cost, C_t is a cost occurring in year t, r is the discount rate per year, S_n is residual or salvage value at year n, and n is the analysis period. The expression assumes costs can be estimated, the discount rate is appropriate and the timing of expenditures is known. It excludes or separately accounts for external environmental and social costs unless those are monetized.

Environmental assessment should consider embodied carbon, operational energy, water use, toxicity, transport, repairability, recycled content and end-of-life recovery. Avoided replacement can be environmentally significant. However, environmental claims must be evidence-based: recycled content, low-carbon cement or timber certification does not automatically establish lower whole-building impact.

Professional ethics require transparent assumptions, competent advice and avoidance of misleading claims. Designers should comply with building regulations, accessibility provisions, fire requirements, occupational safety rules and relevant material standards. Product substitutions require technical review; an apparently equivalent product may differ in fire classification, vapor permeability, warranty, toxicity or installation requirements.

Digital building information models can support material schedules, clash detection, quantity take-off, sequencing and facility management. Sensors and data analytics can monitor moisture, temperature and structural response. Artificial intelligence may assist with option comparison or defect detection, but outputs require competent human verification. Incomplete training data, biased assumptions and unclear accountability make unsupervised automated decisions inappropriate for safety-critical design.

9. Illustrative case: moisture failure in a cavity wall

Background

A new two-storey residential building develops staining and mold on the internal face of several external walls during its first winter. The wall consists of brick veneer, a drained cavity, sheathing, timber framing, insulation and an internal gypsum lining.

Problem

The initial inspection finds that the insulation specification is appropriate and the calculated U-value satisfies the design target. The contractor argues that the problem is indoor humidity. However, staining is concentrated below window openings and at wall–roof junctions.

Analysis

Further investigation identifies discontinuous flashing beneath the windows, blocked cavity weep openings and gaps in the air-control layer around service penetrations. Wind-driven rain enters the veneer, cannot drain consistently, and is transported inward by air leakage. At cold locations near the discontinuities, the internal surface temperature falls below the dew point. The nominal thermal calculation did not include the thermal bridges or air leakage paths.

Approach and solution

The repair strategy includes removing affected finishes, replacing damaged insulation, installing continuous sill and head flashings, clearing and protecting weep openings, sealing the air-control layer at penetrations and adding insulation continuity at the wall–roof junction. Indoor humidity is monitored, but humidity control is treated as a supplementary measure rather than the primary repair. Inspection hold points are added before the cavity is closed.

Outcome

After repairs, moisture readings decline and no new staining appears during the following heating season. The project also introduces photographic records of concealed membranes and a checklist for window installation.

Learning points

1. A material’s laboratory property does not guarantee assembly performance.
2. Water control depends on shedding, drainage, drying and airtightness.
3. Thermal calculations must be interpreted with junctions and workmanship in mind.
4. Concealed work requires inspection before it becomes inaccessible.
5. Diagnosis should follow evidence rather than assign blame to the most visible symptom.

10. Challenges and limitations

Material data are usually measured under controlled conditions and may not represent variable site workmanship, aging, combined exposures or repair history. Generic U-values, strength values and fire classifications should not be transferred blindly between products or assemblies. Sustainability comparisons depend on system boundaries, transport assumptions, service life and data quality.

There are also unavoidable trade-offs. Increasing insulation can reduce heat loss but create drying or detailing challenges. Greater glazing can improve daylight but increase solar gain, overheating and acoustic exposure. High-strength concrete can reduce member size but may increase thermal sensitivity and construction control requirements. Prefabrication can reduce waste while increasing transport and crane dependence.

The correct response is not to seek a universally best material. It is to define performance requirements, understand exposure and sequence, compare whole systems and verify assumptions through standards, testing, competent design and inspection.

Chapter Summary

Construction materials must be understood through both their intrinsic properties and their behavior in assemblies. Concrete and masonry are generally compression-efficient and durable when properly proportioned, detailed and protected from moisture-related deterioration. Metals offer strength and prefabrication advantages but require attention to buckling, corrosion, thermal movement and fire protection. Timber is lightweight and renewable but depends strongly on grain direction, moisture control, biological protection and fire detailing. Glass provides daylight and transparency but is brittle and sensitive to flaws, edge conditions and frame interfaces. Polymers and composites provide lightness, flexibility and corrosion resistance while requiring careful consideration of creep, ultraviolet exposure, fire, bonding and directional behavior.

Building physics concerns coupled heat, moisture, air, sound and fire flows. Thermal resistance and U-value calculations are useful idealizations, but thermal bridges, air leakage, junctions and workmanship determine actual performance. Moisture control requires continuous shedding, drainage, capillary breaks, air control and drying potential. Acoustic and fire performance depend on complete assemblies and interfaces rather than isolated materials.

Constructability requires coordination of sequence, access, tolerances, temporary works, logistics, safety and inspection. Life-cycle decisions should include initial and future costs, environmental impacts, durability, maintenance, replacement and end-of-life. Professional judgment, standards, transparent assumptions and human oversight remain essential, including when digital tools or artificial intelligence are used.

Key Terms

Air barrier: A continuous layer intended to limit uncontrolled air movement through a building enclosure.

Capillary break: A detail or material arrangement that interrupts water movement by capillary action.

Carbonation: Reaction in concrete that lowers pore-solution alkalinity and may reduce reinforcement protection.

Constructability: The extent to which a design can be built efficiently, safely and to the required quality.

Creep: Time-dependent deformation under sustained load.

Ductility: Capacity to deform substantially before fracture.

Durability: Ability to maintain required performance under defined exposure over a specified service life.

Embodied carbon: Greenhouse-gas emissions associated with material extraction, manufacture, transport, construction and related life-cycle stages.

Fire compartmentation: Division of a building into areas that limit fire and smoke spread.

Life-cycle cost: Present-value cost of acquisition, operation, maintenance, replacement and residual value over an analysis period.

Moisture bridge: A discontinuity or path that enables unwanted moisture movement through an assembly.

Thermal bridge: A localized region of increased heat flow caused by geometry or a more conductive material.

Thermal conductivity: Property describing a material’s ability to conduct heat.

Thermal mass: Capacity of a material or assembly to store thermal energy.

Toughness: Capacity to absorb energy before fracture.

U-value: Heat-transfer rate per unit area per unit temperature difference across an assembly.

Vapor-control layer: Layer intended to limit vapor diffusion, with placement determined by climate and assembly design.

Workability: Ease with which a fresh material can be mixed, placed, compacted or finished.

Review Questions

Short Answer Questions

1. Distinguish strength from stiffness and ductility.
2. Why is curing important for concrete?
3. State two mechanisms by which moisture enters buildings.
4. Why can steel require fire protection even though it is non-combustible?
5. What is the purpose of a thermal bridge analysis?

Long Answer Questions

1. Compare concrete, masonry and timber in relation to strength, moisture, fire and durability.
2. Explain how a cavity wall controls rainwater and identify likely consequences of blocked weep openings.
3. Discuss the relationship between material selection and constructability.
4. Explain why acoustic performance depends on interfaces and flanking paths as well as wall mass.
5. Describe how life-cycle cost and environmental impact can be incorporated into material selection.

Analytical / Application Questions

1. A wall has a 0.10 m insulation layer with thermal conductivity 0.035 W/(m·K). Calculate its thermal resistance and explain why the resulting value is not the whole-wall U-value.
2. A steel beam is enclosed in fire protection, but later electrical work creates unsealed penetrations. Analyze the likely consequences and propose a quality-control process.
3. A timber-framed building in a wet climate shows decay at the base of external walls. Develop a diagnosis and remediation plan that considers drainage, capillary breaks, ventilation, sequencing and future inspection.

Multiple Choice Questions with Answers

Question 1

Which property primarily describes resistance to elastic deformation?

A. Strength

B. Young’s modulus

C. Toughness

D. Hardness

Correct Answer: B. Young’s modulus

Question 2

For a homogeneous layer, thermal resistance is calculated as R = L/k. What is the resistance of a 0.08 m layer with conductivity 0.040 W/(m·K)?

A. 0.0005 m²·K/W

B. 0.032 m²·K/W

C. 2.0 m²·K/W

D. 3.2 m²·K/W

Correct Answer: C. 2.0 m²·K/W

Question 3

Which measure most directly interrupts capillary movement of water from the ground into a wall?

A. A capillary break

B. A darker finish

C. A larger internal room

D. A thicker door

Correct Answer: A. A capillary break

Question 4

Why is concrete commonly reinforced with steel?

A. Steel reduces concrete density

B. Concrete provides tension and steel provides compression

C. Concrete is compression-efficient and steel resists tension

D. Steel prevents all concrete shrinkage

Correct Answer: C. Concrete is compression-efficient and steel resists tension

Question 5

Which condition most strongly promotes fungal decay in timber?

A. Persistent moisture

B. Low oxygen and dry conditions

C. Short-term exposure to sunlight only

D. High compressive strength

Correct Answer: A. Persistent moisture

Question 6

What is a major fire-related limitation of unprotected structural steel?

A. It becomes transparent

B. It rapidly loses strength and stiffness when heated

C. It absorbs liquid water into its pores

D. It gains unlimited ductility

Correct Answer: B. It rapidly loses strength and stiffness when heated

Question 7

Which statement about a building U-value is correct?

A. It is the reciprocal of total thermal resistance in the simplified model

B. It measures sound absorption only

C. It is expressed in kilograms per cubic metre

D. It is independent of layer thickness

Correct Answer: A. It is the reciprocal of total thermal resistance in the simplified model

Question 8

Which action best represents constructability planning?

A. Selecting finishes without considering access

B. Ignoring temporary stability until construction begins

C. Coordinating sequence, tolerances, logistics and inspection

D. Maximizing the number of unique components

Correct Answer: C. Coordinating sequence, tolerances, logistics and inspection

Question 9

Why may a high-strength mortar be unsuitable for soft masonry units?

A. It always increases water absorption

B. It may be insufficiently deformable and cause damage under movement

C. It prevents all compression

D. It cannot bond to any masonry

Correct Answer: B. It may be insufficiently deformable and cause damage under movement

Question 10

In life-cycle cost analysis, future costs are commonly converted to present value using which factor?

A. (1 + r)^t

B. 1/(1 + r)^t

C. r − t

D. t/r

Correct Answer: B. 1/(1 + r)^t