RIBA Architecture Parts 1, 2 and 3 Construction Technology and Materials Syllabus

Distinguish pre-tensioned from post-tensioned prestressed concrete.

Pre-tensioning: tendons are stressed before casting and the concrete bonds to them; tension is released after curing (factory-made units). Post-tensioning: tendons in ducts are stressed and anchored after the concrete has cured/hardened (often cast in situ).

Why is steel typically protected for fire, and what is intumescent coating?

Steel loses strength and stiffness at high temperature (critical around $550\,^{\circ}\mathrm{C}$, where it retains roughly 60% strength), so it needs fire protection. Intumescent coatings swell when heated to form an insulating char layer that delays the steel reaching critical temperature.

Compare hot-rolled and cold-formed steel sections.

Hot-rolled sections (e.g. UB, UC) are formed at high temperature into thick structural shapes for primary framing. Cold-formed sections are pressed/rolled from thin gauge sheet at ambient temperature for light framing, purlins and rails; they are lighter but more prone to local buckling.

What is the difference between ferrous and non-ferrous metals, with examples used in construction?

Ferrous metals contain iron and are prone to rust (e.g. carbon steel, stainless steel, cast iron). Non-ferrous metals contain no iron and resist rusting (e.g. aluminium, copper, zinc, lead) — used for cladding, roofing and flashings.

What is galvanic (bimetallic) corrosion and how is it avoided?

It occurs when two dissimilar metals contact in the presence of an electrolyte, causing the less noble (more anodic) metal to corrode preferentially. It is avoided by separating metals (isolation washers/membranes), selecting compatible metals, or using sacrificial coatings.

What is the difference between softwood and hardwood, and is it about hardness?

The distinction is botanical, not about hardness: softwoods come from coniferous (gymnosperm) trees; hardwoods from broad-leaved (angiosperm) trees. Most softwoods are structural/cheaper; many hardwoods are denser/durable, though balsa (a hardwood) is very soft.

Name three engineered wood products and a key benefit of each.

Glulam (glued laminated timber) — large spans/curved members; CLT (cross-laminated timber) — two-way panel action, walls/floors with low embodied carbon; LVL/Glulam/I-joists — dimensionally stable, consistent strength from defect dispersion. Plywood/OSB provide sheet bracing.

What are the two main timber decay risks and the moisture threshold for fungal decay?

Wet rot and dry rot (fungal decay), plus insect attack. Fungal decay generally requires timber moisture content above about 20%; keeping timber dry (below ~20% MC) prevents rot. Dry rot (Serpula lacrymans) is most dangerous as it can spread through masonry.

What is the difference between a brick wall built in stretcher bond versus English bond?

Stretcher bond shows only the long faces (stretchers) — typical of a single-leaf/cavity wall outer skin. English bond alternates courses of headers and stretchers, bonding two leaves into a solid wall for greater strength.

Compare the structural roles of brick, concrete block and aircrete (AAC) block.

Fired clay bricks: durable, attractive, used for facing and load-bearing. Dense concrete blocks: high strength/compressive capacity for structural inner leaves. Aircrete (autoclaved aerated concrete) blocks: lightweight, good thermal insulation and workability but lower strength.

Why is masonry strong in compression but weak in tension, and how is this addressed?

Mortar joints have little tensile/flexural strength, so masonry cracks under tension or bending. It is addressed by keeping masonry in compression (arching), adding bed-joint reinforcement, using lintels over openings, and tying/buttressing for lateral support.

What is the function of float glass and how is toughened (tempered) glass made?

Float glass is annealed glass made by floating molten glass on molten tin, giving flat, distortion-free panes. Toughened glass is heated then rapidly cooled to put surfaces in compression, making it ~4–5x stronger and causing it to shatter into small blunt granules (safety glass).

Compare toughened and laminated safety glass.

Toughened glass is heat-treated to be stronger and fractures into small harmless granules but offers no residual barrier. Laminated glass bonds layers with a PVB/EVA interlayer; on breaking, fragments adhere to the interlayer, maintaining a barrier and giving security/acoustic/UV benefits.

What are thermoplastic versus thermosetting polymers, with construction examples?

Thermoplastics soften on heating and can be remoulded (e.g. PVC, polycarbonate, acrylic, polyethylene). Thermosets cure into an irreversible cross-linked network and char rather than melt (e.g. epoxy, polyurethane, GRP resins, phenolics).

Define embodied carbon and how it differs from operational carbon.

Embodied carbon is the greenhouse gas emissions associated with materials and construction processes across a building's life cycle (extraction, manufacture, transport, construction, maintenance, end-of-life). Operational carbon is emissions from running the building (heating, cooling, lighting). Together they form whole-life carbon.

What life-cycle stages (RICS/EN 15978) are commonly cited for embodied carbon, and what does 'cradle to gate' mean?

Stages A (product A1–A3 and construction A4–A5), B (use), C (end-of-life), and D (beyond system boundary). 'Cradle to gate' covers A1–A3 (raw material supply, transport, manufacturing) up to the factory gate; 'cradle to grave' adds use and disposal.

Why does material selection significantly affect embodied carbon, and name low- and high-embodied-carbon materials.

Materials with energy-intensive processing have high embodied carbon. High: aluminium, steel, cement/concrete (clinker), plastics. Low: timber and other bio-based materials (which also sequester carbon), and reused/recycled materials. Specifying cement replacements (GGBS, fly ash) reduces concrete's carbon.

Describe a typical masonry cavity wall build-up from outside to inside.

Outer leaf (facing brick/block) — clear cavity (often part-filled or full-fill insulation) — wall ties spanning the cavity — inner leaf (blockwork) — and an internal finish (plaster/dry lining). The cavity drains and stops moisture crossing to the inner leaf.

What is the purpose of wall ties and a cavity tray in cavity construction?

Wall ties connect the two leaves so they act together against lateral loads while keeping the cavity open. A cavity tray is a barrier/DPC over openings or at floor levels that collects water running down the cavity and directs it out through weep holes to the exterior.

Why are weep holes provided and at what spacing are they typically placed?

Weep holes allow water collected within the cavity (on cavity trays/DPC) to drain to the outside, preventing build-up and penetration. They are typically provided at roughly $450\,\mathrm{mm}$ centres (about every other perpend) above cavity trays and at the base of the cavity.

Compare a warm flat roof, a cold flat roof and an inverted (protected membrane) roof.

Warm roof: insulation above the structural deck, below the waterproofing (warm structure, no ventilation needed). Cold roof: insulation between/below joists with waterproofing above — requires ventilation to avoid condensation (now discouraged). Inverted roof: insulation laid above the waterproofing membrane, protecting it from thermal/UV stress, held by ballast.

Name the main elements of a traditional pitched roof and the typical minimum pitch distinction.

Elements: rafters, ridge, purlins, wall plate, ceiling joists/ties, battens and covering. 'Pitched' generally means a roof above about $10^{\circ}$; 'flat' roofs are typically below $10^{\circ}$ (with a minimum fall of around $1{:}40$ design to achieve $1{:}80$ finished to shed water).

What is a thermal bridge and what consequences does it cause?

A thermal bridge (cold bridge) is a localised area of the envelope with higher heat flow than surroundings (e.g. at junctions, lintels, balconies, where insulation is bridged by a conductive element). Consequences: increased heat loss, lower internal surface temperatures, risk of surface condensation and mould, and pattern staining.

What is the purpose of insulation continuity, and what is a 'psi value'?

Insulation continuity means the insulation layer wraps unbroken around the building (and air barrier continuity for airtightness), minimising thermal bridges. A psi value ($\psi$) is the linear thermal transmittance quantifying extra heat loss at a junction, in $\mathrm{W/(m \cdot K)}$, used to calculate junction heat loss.

What is a rainscreen cladding system and how does it manage water?

A rainscreen is an outer cladding skin set off a backing wall with a ventilated/drained cavity. The outer leaf takes the brunt of rain (often open-jointed/pressure-equalised); any water passing the joints drains down the cavity and is vented, while the backing wall carries the airtight/insulation/weather line.

What is the difference between a ventilated/drained rainscreen and a pressure-equalised rainscreen?

A drained-and-ventilated rainscreen relies on draining water that gets behind the cladding and ventilating to dry it. A pressure-equalised rainscreen uses a compartmented, vented cavity so air pressure behind the cladding equals external pressure, removing the pressure difference that drives water through joints.

Distinguish stick-system from unitised curtain walling.

Stick system: mullions, transoms and infill glazing are assembled piece-by-piece on site — flexible but slower/weather-dependent. Unitised system: storey-height factory-assembled panels are craned into place and interlock — faster on-site erection, better quality control, suited to tall buildings.

What does a window's U-value and g-value (solar factor) represent?

The U-value is the rate of heat transmission through the unit, $\mathrm{W/(m^{2} \cdot K)}$ — lower means better insulation. The g-value (solar heat gain coefficient) is the fraction of incident solar energy transmitted, between $0$ and $1$ — higher means more solar gain.

How does double or triple glazing reduce heat loss, and what improves it further?

Sealed cavities of low-conductivity gas (often argon) between panes reduce conductive/convective heat loss. Performance is improved by low-emissivity (low-E) coatings that reflect infrared back inward, wider/optimised cavity widths, warm-edge spacers, and an additional pane (triple glazing).

What is a damp-proof course (DPC) and a damp-proof membrane (DPM), and where is each used?

A DPC is a horizontal (and sometimes vertical) barrier in walls preventing rising damp from the ground travelling up the masonry, placed at least $150\,\mathrm{mm}$ above external ground level. A DPM is a barrier (often polythene) in/under floor slabs preventing ground moisture rising into the floor.

Compare tanking (Type A barrier), drained cavity (Type C) and structurally integral (Type B) basement waterproofing.

Per BS 8102: Type A (barrier) — applied waterproof membranes/coatings on the structure. Type B (structurally integral) — the watertight concrete structure itself resists water. Type C (drained cavity) — water is allowed in and managed/drained via an internal cavity drainage system to a sump/pump.

What is interstitial condensation and how does it differ from surface condensation?

Surface condensation forms on visible cold internal surfaces when their temperature falls below the room air dew point. Interstitial condensation forms within the thickness of the construction when warm, moist air diffuses through and reaches a layer below dew point — hidden, and damaging because it can rot/corrode concealed elements.

How does a vapour control layer (VCL) prevent interstitial condensation, and where is it positioned?

A VCL is a low vapour-permeability membrane that limits moisture vapour diffusing into the construction from the warm side. It is placed on the warm (internal) side of the insulation, while the outer layers are kept more vapour-open so any moisture that gets in can escape ('vapour-open outward').

What is the dew point and why is it important in moisture control?

The dew point is the temperature at which air becomes saturated (100% relative humidity) and water vapour condenses to liquid. In construction, condensation risk occurs wherever a surface or internal layer falls below the dew point of the adjacent air; designers keep the dew point outside vulnerable layers.

What construction conditions promote mould growth, and what relative humidity is critical?

Mould needs moisture, nutrients (dust/organic matter) and moderate temperature. It typically grows where surface relative humidity persistently exceeds about 80% (or surfaces stay damp), commonly at thermal bridges and poorly ventilated cold corners. Control via insulation continuity, ventilation, heating and reducing moisture sources.

Why does mass help acoustic insulation, and what is the mass law?

Heavier (denser) elements vibrate less for a given sound pressure, so they transmit less airborne sound. The mass law states that for a single solid panel, airborne sound insulation rises by about $6\,\mathrm{dB}$ for each doubling of mass per unit area (or doubling of frequency).

Distinguish airborne from impact sound, and how each is controlled.

Airborne sound (speech, music) travels through air and is reduced by mass, isolation and absorption. Impact sound (footsteps) is structure-borne from direct impact; it is controlled by resilient layers, floating floors, soft coverings and isolating the source from the structure to break the transmission path.

What is flanking transmission and how is it reduced?

Flanking transmission is sound that bypasses the main separating element by travelling through adjoining/connected elements (flanking walls, floors, junctions). It is reduced by detailing junctions to break continuity — discontinuous construction, flexible isolation, breaking rigid paths, and using independent/decoupled leaves.

Explain reaction to fire versus fire resistance.

Reaction to fire describes how a material contributes to a fire (ignitability, flame spread, heat release) — classified by Euroclasses A1, A2, B–F. Fire resistance is the ability of a building element (wall, floor, door) to maintain its function during fire for a period, measured in minutes against Loadbearing capacity (R), Integrity (E) and Insulation (I).

What do the REI fire-resistance criteria mean, e.g. REI 60?

R = loadbearing capacity (the element keeps supporting load); E = integrity (it resists passage of flames/hot gases); I = insulation (the unexposed face stays below a temperature limit). REI 60 means the element satisfies all three criteria for $60$ minutes.

What is compartmentation and the role of cavity barriers and fire stopping?

Compartmentation divides a building into fire-resisting cells (compartment walls/floors) to limit fire and smoke spread and protect escape routes. Cavity barriers close concealed cavities to stop fire/smoke spreading unseen; fire stopping seals service penetrations and joints to maintain the fire resistance of the compartment line.

What are the main causes and remedies for efflorescence on masonry?

Efflorescence is a white salt deposit left when water carrying soluble salts migrates to the masonry surface and evaporates. It is usually cosmetic; remedies include allowing it to weather off, dry brushing, controlling water ingress (keeping masonry dry), and using low-salt materials. Persistent efflorescence signals an ongoing moisture problem to fix.

What is sulfate attack on concrete/mortar and how is it prevented?

Sulfates (from groundwater, soils or some bricks) react with cement hydrates (notably tricalcium aluminate) to form expansive ettringite, causing expansion, cracking and softening. Prevention: use sulfate-resisting cement (low C3A), low-permeability concrete, and protect against sulfate-bearing water.

Describe the mechanism of reinforcement corrosion (carbonation and chloride attack) and its visible symptoms.

Concrete's alkalinity passivates steel; carbonation ($\ce{CO2}$ lowering pH) or chloride ingress destroys the passive layer, letting steel rust. Rust expands (up to several times its volume), cracking and spalling the cover concrete. Symptoms: cracking along bar lines, rust staining and spalling ('concrete cancer').

Distinguish rising damp, penetrating damp and condensation as causes of dampness.

Rising damp: ground moisture rising up walls by capillarity (failed/absent DPC), showing a tide mark low on walls. Penetrating damp: water entering laterally through the fabric (defective roof, walls, flashings, blocked cavity). Condensation: moisture from internal air depositing on cold surfaces — diagnosed by location, pattern and seasonality before remediation.