Construction Tech Flashcards

Question

What is a portal frame? Why is it advantageous?

Answer 1

A steel portal frame is a structural system, most often used for low-rise buildings, that uses rigid connections between its vertical columns and horizontal rafters. This design allows the frame to stand on its own without internal bracing, creating large, open, and unobstructed spans. A building is constructed by repeating the "portal" shape in parallel along its length. Formed of columns, rafters, purlins, an apex joint and haunches at the connection between the columns and the rafters. Commonly used in warehouses and storage units, barns, supermarkets etc.

Answer 2

a blue roof is a system of rainwater retention and controlled drainage on roofs. This is a great method of water attenuation and management of stormwater, and can be key to sustainability in buildings - particularly in urban areas where a ground level solution may not be possible due to lack of space.

Answer 3

Underpinning strengthens a building's foundation by excavating and replacing soil in sections to extend or widen the existing foundation. This is done in phases, such as with the traditional mass concrete method where the soil is dug out in box-like sections and filled with concrete, or with other methods like beam and base or resin injection. These techniques are used when foundations are weak due to soil conditions, poor original construction, or added structural loads, often to fix subsidence

Answer 4

Used when continuous loading requires support, such as a load bearing wall, or where load bearing columns are too close together for pad foundations to be practical.

Answer 5

Raft foundations have the advantage of reducing differential settlements as the concrete slab resists differential movements between loading positions. They are often needed on soft or loose soils with low bearing capacity as they can spread the loads over a larger area.

Answer 6

Lead codes are based on thickness and defined under BS EN 12588 - Rolled Lead Sheet Specification: * Code 3 (1.32 mm) – Soakers, light flashings * Code 4 (1.80 mm) – Step and apron flashings * Code 5–6 (2.24–2.65 mm) – Gutters, dormers, flat roof bays * Code 7–8 (3.15–3.55 mm) – Wide gutters, domes, heritage work The purpose of these codes is to ensure the correct type of lead is used for different parts of a roof, based on durability, flexibility, and weight.

Answer 7

1. Correct lead code to be used (usually code 4) 2. prepare surface (ensure it is clean, dry and free of debris), an underlay should be used to isolate the lead from the masonry substrate. 3. Cut and shape lead using lead dressing tools (max length 1.5m for Code 4) 4. chase lead into mortar joint (brickwork mortar should be raked out to a depth of at least 25mm), minimum 150mm upstand 5. seal the joint with lead sealant (not mortar, to allow for movement & prevent cracking) 6. leave a 5mm gap between lead sections to allow for thermal movement, use laps of at least 100mm where lead sheets overlap. 7. Apply patination oil to the lead surface to prevent staining and oxidation. BS 6915:2001+A1:2014 – Installation of Lead Sheet, Flashings and Weathering's. This British Standard provides a code of practice for installing lead sheet in roofing and cladding. Attention should be drawn to the Control of Lead at Work Regulations

Answer 8

less than 10 degrees for a flat roof between 10 - 80 degrees for a pitched roof above 80 degrees for a vertical wall

Answer 9

BS EN 636 is the European standard for plywood, classifying it into three main types based on moisture resistance and intended service conditions: BS EN 636-1: Dry Conditions Use: Interior applications where the plywood is not exposed to moisture. Examples: Furniture, interior wall linings, ceilings. BS EN 636-2: Humid Conditions Use: Interior applications with occasional exposure to moisture or high humidity. Examples: Kitchen or bathroom furniture, sheltered external uses. BS EN 636-3: Exterior Conditions Use: External applications where the plywood is exposed to weather and wet conditions. Examples: External cladding, roofing, site hoardings.

Answer 10

1. TIMBER BOARDING Usually softwood, either tongue and groove or square-edged Pros: Strong, breathable, and suitable for nailing lead or slate. Cons: Heavier and more expensive than sheet materials. 2. PLYWOOD DECK Plywood is engineered wood panel made from thin layers of wood vener Use: Flat or pitched roofs, especially under membranes or built-up felt systems. Pros: Stable, smooth surface, good for adhesives. Cons: Must be correctly specified for moisture exposure (e.g. EN 636-3 for exterior). 3. ORIENTED STRAND BOARD An engineered board made from compressed wood strands and adhesives. Usually OSB/3 or OSB/4 for load-bearing and moisture resistance. Pros: Cost-effective, uniform, and widely available. Cons: Edges must be protected from moisture ingress. 4. CHIPBAORD Made from wood particles bonded with resin. use: occasionally used in warm roofs with VCLs pros: cheap & easy to install cons: poor moisture resistance, not suitable for exposed or ventilated roofs. 5. CROSS-LAMINATED TIMBER (CLT) Engineered timber panels with cross-laminated layers Use: High-performance or sustainable buildings, often in modern architecture. Pros: High strength, dimensional stability, and sustainability. Cons: Expensive and requires specialist installation.

Answer 11

A deleterious material is defined as any substance that poses a risk to health, safety, or the environment, or that can compromise the structural integrity of a building or structure.

Answer 12

1. Chrysotile (White Asbestos) Most common type used in UK buildings. Found in: cement sheets, roofing, floor tiles, textured coatings. 2.Amosite (Brown Asbestos) Used in insulation boards, ceiling tiles, and thermal insulation. 2. Crocidolite (Blue Asbestos) Highly hazardous, used in spray coatings and pipe insulation. 1985: Ban on blue (crocidolite) and brown (amosite) asbestos. 1999: Complete ban on all asbestos types (including white chrysotile).

Answer 13

Where Found in Older Buildings Pipe lagging and boiler insulation. Ceiling tiles and textured coatings (e.g., Artex). Floor tiles and adhesives. Cement roofing sheets and panels.

Answer 14

Lead is toxic and can cause a range of health issues, particularly through inhalation or ingestion of lead dust, fumes, or vapour. In the UK, lead is considered a deleterious material in construction primarily due to its serious health risks, especially when disturbed during renovation, demolition, or maintenance of older buildings. Lead is commonly found in: Old paint (especially pre-1960s), full ban on lead-based paint in 1992 Roof flashings and gutters Water pipes (Banned in new plumbing in 1970) Solder joints Decorative elements and stained glass The Control of Lead at Work Regulations 2002 require employers to assess and control exposure risks. ✅ Mitigation Measures Use substitute materials where possible. Leave lead paint undisturbed if in good condition. Employ wet methods for paint removal. Use respiratory protective equipment (RPE). Conduct risk assessments before work begins.

Answer 15

RAAC is a lightweight, precast concrete product used in UK buildings from the 1950s to the mid-1990s, primarily in: Flat roofs Floor panels Wall panels Plant rooms distinct features: - 600mm wide planks with V shaped edges, a textured surface, bubbles and a crumbly touch when poked with a screwdriver. It lacks traditional aggregate and is made by introducing aluminium powder into the mix, creating gas bubbles that reduce density. While it was valued for its lightweight and thermal properties, it is now considered structurally vulnerable. ⚠️ Why Is RAAC a Concern? Structural instability: RAAC can deteriorate over time, especially when exposed to moisture, leading to reinforcement corrosion, cracking, and sudden collapse. Limited lifespan: Often cited as ~30 years, but this varies based on maintenance, load changes, and environmental exposure. Hidden risk: RAAC may be concealed behind finishes or coatings, making identification difficult. Health & safety: Collapse risk is heightened in buildings with poor roof coverings or water ingress. RAAC failure has led to closures of schools, hospitals, and public buildings. If you confirm or suspect the presence of RAAC planks you should seek guidance from a competent structural engineer to assess it and develop a management plan.

Answer 16

🏗 Emerging Construction Technologies 3D Printing (Additive Manufacturing) Used for creating building components or entire structures. Benefits: Reduced waste, faster build times, and design flexibility. Building Information Modelling (BIM) with AI Integration Advanced BIM platforms now use AI for predictive maintenance and clash detection. Enables real-time collaboration and digital twins. Robotics and Automation Robotic bricklaying, concrete pouring, and site surveying. Improves precision and reduces labour costs. Drones for Surveying High-resolution aerial mapping and thermal imaging for inspections. Speeds up site analysis and progress monitoring. Augmented Reality (AR) & Virtual Reality (VR) Used for immersive design reviews and on-site guidance. Enhances client engagement and reduces errors. Smart Sensors & IoT Embedded sensors for structural health monitoring and energy efficiency. Enables predictive maintenance and real-time data analytics.

Answer 17

🧱 Emerging Construction Materials Self-Healing Concrete Contains bacteria or polymers that repair cracks automatically. Extends lifespan and reduces maintenance costs. Cross-Laminated Timber (CLT) Sustainable alternative to steel and concrete for structural elements. High strength-to-weight ratio and carbon sequestration benefits. Graphene-Enhanced Concrete Improves strength, durability, and reduces carbon footprint. Allows thinner, lighter structures. Aerogel Insulation Extremely lightweight and highly insulating material. Ideal for energy-efficient retrofits. Phase-Change Materials (PCMs) Used in walls and ceilings to regulate indoor temperature. Improves thermal comfort and energy efficiency. Recycled Plastic Composites Used for decking, cladding, and structural components. Reduces landfill waste and promotes circular economy. Transparent Aluminum (Aluminum Oxynitride) Ultra-strong, transparent material for windows and facades. Offers security and durability.

Answer 18

A thermally broken window frame refers to a frame design that incorporates a material with low thermal conductivity (usually a plastic or resin) between the inner and outer parts of the frame. This “thermal break” acts as an insulating barrier to reduce heat transfer through the frame. - Without a thermal break: Metal frames (like aluminum) conduct heat very efficiently, which can lead to significant heat loss in winter and heat gain in summer. - With a thermal break: The insulating layer interrupts the thermal path, improving energy efficiency and reducing condensation on the interior surface.

Answer 19

✅ Limiting U-values (maximum allowed) (Values in W/m²·K – lower is better insulation) Walls - 0.26 (new fabric) Floors- 0.22 Roofs- 0.18 (rennovation flat) - 0.16 (rennovation pitched) Windows- 1.6 Rooflights- 2.2 Doors- 1.8 (varies by glazing %) Flat roofs generally have higher U-values (less strict) because: - They are harder to insulate to very low U-values without increasing thickness significantly. - Structural and waterproofing constraints limit insulation depth. Pitched roofs can achieve lower U-values more easily: - Greater space for insulation in lofts or rafter zones. - Easier to layer insulation without affecting roof design.

Answer 20

The following are maximum U-values, the lower the value, the better the thermal performance. New build targets are: - 0.11 for pitched - 0.18 for flat Rennovation targets are: - 0.16 for pitched -0.18 for flat Flat roofs generally have higher U-values (less strict) because: - They are harder to insulate to very low U-values without increasing thickness significantly. - Structural and waterproofing constraints limit insulation depth. Pitched roofs can achieve lower U-values more easily: - Greater space for insulation in lofts or rafter zones. - Easier to layer insulation without affecting roof design.

Answer 21

1. Window Air Conditioners Description: Self-contained units installed in a window or wall opening. Best for: Single rooms or small spaces. Pros: Low cost, easy installation. Cons: Limited capacity, blocks window space. 2. Split Air Conditioning Systems Description: Consists of an indoor unit (evaporator) and an outdoor unit (condenser), connected by refrigerant pipes. Best for: Individual rooms or zones. Pros: Quiet operation, efficient cooling. Cons: Higher installation cost than window units. 3. Multi-Split Systems Description: One outdoor unit connected to multiple indoor units. Best for: Homes or small offices with multiple rooms. Pros: Space-saving outdoor setup. Cons: Complex installation, higher cost. 4. Central Air Conditioning Systems Description: Large system that cools air at a central location and distributes it via ductwork. Best for: Large buildings, offices, or entire homes. Pros: Uniform cooling, can integrate heating. Cons: High installation and maintenance cost. 5. VRF/VRV Systems (Variable Refrigerant Flow/Volume) Description: Advanced multi-split system with variable refrigerant flow for precise control. Best for: Large commercial buildings or high-end residential. Pros: Energy-efficient, flexible zoning. Cons: Expensive and requires skilled installation.

Answer 22

VRF (Variable Refrigerant Flow) / VRV (Variable Refrigerant Volume) systems are advanced HVAC technologies designed for large buildings or spaces that require flexible and energy-efficient cooling and heating. Concept: A VRF/VRV system uses refrigerant as the cooling and heating medium, circulating it through a network of indoor units connected to one or more outdoor units. Key Feature: The amount of refrigerant flowing to each indoor unit is variable, allowing precise temperature control in different zones. Advantages: - Energy Efficiency: Only uses the energy needed for each zone. - Zoning Flexibility: Ideal for buildings with varied occupancy and usage. - Space Saving: No large ductwork required. - Quiet Operation: Indoor units are very quiet. Disadvantages: - High Initial Cost: More expensive than traditional systems. - Complex Installation: Requires skilled design and commissioning. - Maintenance: Specialized technicians needed

Answer 23

1. Durability and Longevity - Lead is extremely resistant to corrosion and weathering, which makes it last for decades—often over 50 years if installed correctly. - It performs well in harsh climates, including areas with heavy rain, frost, or pollution. 2. Malleability - Lead is highly malleable, meaning it can be easily shaped and dressed around complex roof details such as valleys, chimneys, and dormers. - This flexibility ensures a tight seal and reduces the risk of leaks. 3. Self-Healing Properties - Lead develops a protective patina over time, which helps prevent corrosion and can even “heal” minor scratches, maintaining its integrity. 4. Sustainability - Lead is 100% recyclable, and most lead flashings today come from recycled sources, making it an environmentally responsible choice. 5. Compatibility - It works well with most roofing materials (slate, tile, etc.) and is less likely to react adversely compared to some metals. 6. Fire Resistance - Lead is non-combustible, adding an extra layer of safety in case of fire. Potential Downsides to Consider: Drawbacks: - Weight: Lead is heavy, so proper support is needed. - Cost: It’s generally more expensive than alternatives like plastic or aluminum. - Health Concerns: Handling lead requires care due to its toxicity; installers must follow safety guidelines.

Answer 24

* If you replace or renovate more than 50% of the flat roof surface, or more than 25% of the building envelope, you must upgrade thermal performance to meet Part L standards. * Simple overlay repairs (without removing the waterproofing) are generally considered maintenance and may not trigger Part L, but upgrading insulation is good practice. * Needs to achieve a 0.18 max u value * Must include a condensation risk assessment and appropriate vapour control layers to prevent interstitial condensation. * Detailing around edges, upstands, and penetrations must minimize thermal bridges. * Ensure continuity of air barrier when upgrading insulation. * If achieving the target U-value is not technically feasible or the payback period exceeds 15 years, you must upgrade to the best level possible. * Building Control approval is required, and you’ll need a Building Control Completion Certificate after works. * Fire Safety: Membrane choice must comply with Broof(t4) external fire performance.

Answer 25

Steel-framed buildings are strong and versatile, but they can develop certain defects over time, often due to design, construction, or environmental factors. * Corrosion - exposure to moisture, condensation or aggressive environments, common with poor protective coatings. * Fire protection failure - damaged or missing intumescent coatings, steel looses its strength rapidly in fire, comprising structural integrity. * Thermal movement - steel expands and contracts significantly with temp changes, can lead to cracking of internal finishes and joint failure if not properly accommodated. * Connection failures, buckling due to inadequate bracing.

Answer 26

1. External Fire Performance * Roof coverings must comply with EN 13501-5 classification: ○ BROOF(t4) = Best performance (resists fire spread). ○ CROOF, DROOF, EROOF, FROOF = progressively lower performance. * Most flat roofs are required to achieve BROOF(t4) rating for compliance. 2. Separation Distances * Minimum distance from roof edges to boundaries depends on: ○ Roof covering classification. ○ Building size and use. * This prevents fire spread between properties. 3. Compartmentation * Where a compartment wall meets the roof, the junction must maintain fire resistance. * Upstands and insulation around these areas must comply with fire guidance.

Answer 27

* VAV = Variable air volume, VRF = Variable refrigerant flow (one is air based, one is refrigerant based, both are variable HVAC systems that allow control of the internal temperature) * VAV Supplies conditioned air from a central air handling unit (AHU). Airflow varies to maintain temperature in different zones, Less efficient for heating/cooling compared to VRF. * VRF Uses refrigerant directly to provide heating and cooling, Outdoor unit connects to multiple indoor units via refrigerant piping. No large ductwork needed, Each indoor unit can operate independently (zoning). * VAV = Air distribution system (ventilation + temperature control). * VRF = Refrigerant distribution system (temperature control only; ventilation must be separate).

Answer 28

1. Stack Effect ○ Warm air inside the building rises and escapes through high-level openings (e.g., roof vents). ○ This creates a pressure difference that draws cooler, fresh air in through low-level openings. 2. Cross Ventilation ○ Openings on opposite sides of the building allow wind to push fresh air through, flushing out stale air. 3. Thermal Mass & Night Purge ○ Buildings often use thermal mass (e.g., concrete floors) to absorb heat during the day. ○ At night, cool air flows in to purge heat, reducing reliance on air conditioning. 4. Controlled Louvres & Dampers ○ Automated or manual louvres regulate airflow based on temperature, CO₂ levels, or occupancy. 5. Minimal Energy Use ○ No fans or compressors—just natural forces (wind and buoyancy). Often integrated with sensors for smart control. Benefits 1. Lower energy consumption compared to mechanical ventilation. 2. Improved indoor air quality and occupant comfort. 3. Reduced carbon footprint

Answer 29

An FCU (Fan Coil Unit) is a key component in HVAC systems, mainly used for heating and cooling individual spaces. * Provides localized heating or cooling in a room or zone. * Helps maintain thermal comfort without needing a full ducted system. * Common in offices, hotels, and residential apartments. How it works: * Heat Exchange * The FCU contains a coil (hot water, chilled water, or refrigerant). * Water or refrigerant flows through the coil from a central plant or heat pump. * Air Movement * A fan draws room air across the coil. * Heat is transferred: ○ Heating mode: Warm water heats the air. ○ Cooling mode: Chilled water cools the air. * Air Distribution * The conditioned air is blown back into the room. Some FCUs include filters for air quality improvement.

Answer 30

1. Bolted Connections * Beam-to-Column End Plate Connection ○ Steel beam end plate bolted to column flange. * Column Splice ○ Bolted plates joining two column sections vertically. * Base Plate Connection ○ Column fixed to concrete foundation using anchor bolts. 2. Welded Connections * Beam-to-Column Welded Flange ○ Beam flange welded directly to column flange for rigid frame. * Full Penetration Butt Weld ○ Used for heavy structural joints requiring high strength.

Answer 31

1. Modern Methods of Construction (MMC) - off-site manufacturing, inreased quality and efficiency. 2. Cross-Laminated Timber (CLT) - Engineered timber product, renewable when sustainably sourced. 3. Digital Desing and Building Information Modelling (BIM) 4. Low-carbon conrete and alternative materials - e.g. geopolymer concretes with reduced embodied carbon. 5. Smart Building technologies (sensir technologies & digital controls) 6. Renewable & low-carbon building services (ASHP, PB, MVHR) These technologies aim to improve sustainability, efficiency and building performance.

Answer 32

MMC refers to off‑site manufacturing of building components or whole modules in a factory environment, which are then transported to site and assembled. Key benefits: Improved quality control due to factory conditions Faster construction programmes Reduced waste and site disruption Improved health and safety Supports sustainability through efficiency Key disadvantages: High upfront manufacturing costs Transport constraints and crane requirements Design flexibility can be limited once production starts Perceived market resistance in some sectors

Answer 33

CLT (CORSS-LAMINATED TIMBER) is an engineered timber product made by layering timber boards at right angles and bonding them together. It is used for structural walls, floors and roofs in multi‑storey buildings. Key benefits: Lower embodied carbon compared to steel and concrete Lightweight, reducing foundation sizes Fast erection times Renewable material when sourced sustainably Key disadvantages: Fire performance concerns (managed through design and regulation) Moisture sensitivity during construction Limited UK supply chain compared to traditional materials May require additional acoustic treatment

Answer 34

BIM uses digital 3D models to coordinate design, construction and operation of buildings. It allows multiple disciplines to work on a shared model containing physical and performance data. Key benefits: Improved coordination and clash detection Better cost and programme certainty Supports whole‑life asset management Reduces errors and rework Key disadvantages: Training and software costs Upfront data/ info requirements - not always suitable for existing buildings Requires cultural change and collaboration Data management and responsibility/ ownership issues Smaller practices may face implementation challenges

Answer 35

BS 5839 is the British Standard that provides best‑practice guidance on the design, installation and maintenance of fire detection and alarm systems. In commercial buildings, BS 5839‑1 defines system categories for life and property protection. As a building surveyor, I understand the purpose of these systems, how to recognise common categories such as L3, and the importance of ensuring systems remain appropriate following alterations or change of use: - Must be tested weekly - serviced every 6 months

Construction Tech Flashcards

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