�SUPERSTRUCTURE

Dr Adewale Abimbola, FHEA, GMICE.

www.edulibrary.co.uk

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Aim & Objectives

Aim: Superstructure

Objectives: At the end of the lesson, the students should be able to:

• Differentiate between the primary and secondary elements of a superstructure.
• Explain the design criteria for superstructure.
• Explain the functional characteristics for superstructure.

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Learning Outcomes and Assessment Criteria

(Part of) P4 – Explain the functional characteristics and design criteria for the primary and secondary elements of a superstructure.

Introduction

• Superstructure – is the section of a building above the ground or damp proof course level. The different elements of a superstructure are:
• Primary elements – are interconnected elements or core of the superstructure that provide loadbearing function. These include floors, walls, roofs, and stairs.
• Secondary elements – are elements that complete the spaces between the primary elements and do not provide loadbearing advantage. These include doors, partition walls, raised access flooring, windows, ceiling, chimneys, and so on. These can include finishing elements.
• Finishing elements – are elements that add to the aesthetic qualities of the primary and secondary elements. This include plastering, paints, cladding, and so on.

Introduction

• In this lesson, focus will only be given to the functional requirements and not the components of elements such as floors, walls, roofs, floor, stairs and finishes.
• The following points under each element can be personally researched for proper understanding.

• Walls
• External walls (e.g., cavity wall, timber frame, lightweight steel)
• Wall cladding (e.g., panel systems, infill systems, composite panel systems)
• Internal partition walls (e.g., timber framed, steel framed, manufactured panels)
• Roofs
• Roof types (e.g., pitched, flat roof systems)
• Roof construction (e.g., beams, rafters, fascia, battens)
• Roof coverings.

• Floors
• Floor type (e.g., ground floors, intermediate floors)
• Floor construction (e.g., decking, subfloor, screed)
• Floor finishes (e.g., timber, stone, sheet, poured)
• Staircases
• Staircase types (e.g., straight, dog-leg, circular, helical)
• Stair construction (e.g., timber, concrete, metal)
• Means of escape
• Stair elements (e.g., tread, rise, stringer, nosing)
• Finishes
• Ceiling, wall, and floor finishes.

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Superstructure Design Criteria

BUILDING/INFRASTRUCTURE USE�Building structures are principally influenced by the intended use of the building.

Superstructure Design Criteria

Table 1. Typical Building/Structures in the Built Environment

Superstructure Design Criteria

STRUCTURAL FORM

• Structural forms play a crucial role in maintaining a building's equilibrium.
• These forms can be categorized into solid, skeletal, panel, and membrane structures.

Solid Structures

• It involve walls that serve both enclosing and load-bearing functions, consistently under compressive stress.
• Throughout history, materials like timber, stone, and bricks were utilized for economical construction, especially in low-rise buildings. In contemporary construction, concrete and blocks are additional options.
• The stability of solid structures is derived from the weight, thickness, and internal support of each wall

Superstructure Design Principles

Skeletal Structures

• Skeletal structures employ frameworks of steel, concrete, or timber members arranged to efficiently carry and transmit loads to the ground through the foundation.
• The load is concentrated and conveyed through columns and stanchions.

Methods to resist wind load:

• Inherent stiffness of the joints – bolted or welded –
• Purlins and sheeting rails with their associated claddings –
• Bracing between portals at wall and roof positions –
• Masonry panels built between portal frames acting as shear walls –
• Internal walls designed to resist loading from the frame.

Superstructure Design Criteria

Figure 2. Tensile membrane structures. (Asia Tents Manufacturing, 2016)

Figure 1. Insulated concrete forms (The Taunton Press, 2017)

Superstructure Design Criteria

Unity

• Unity is achieved when individual parts contribute cohesively to the building mass. 
• Unity of shape; the repetition of form has a powerful effect on a person’s perception and acceptance of the building.
• Unity of scale is essential for planning authorities, and adherence to similarly sized structures may be mandated. 
• The dominance of one element or an oversized building can disrupt the unity of scale.

Figure 3. The Taj Mahal (Fidanci, 2023)

Figure 4. The Pentagon.

Superstructure Design Criteria

Balance and symmetry

• Balance and symmetry in design involve creating an impression of equal weight on opposite sides of the vertical centre, contributing to visual harmony.
• A well-designed building requires a focal point, such as the entrance, serving as the visual centre to which the eye is naturally drawn.
• This focal point also functions as the pivot for achieving balance, mirroring the principles of physical balance.

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Duality

• Duality represents the intersection between practical necessities and visual balance, encompassing elements like detail, colour, texture, or finish.
• It involves a harmonious integration of function and form.
• In the design process, the primary consideration should be the purpose or function of the building, ensuring a balanced synthesis with its form.

Figure 6. The Sydney Opera House.

Figure 5. The Pagoda.

Superstructure Design Criteria

Superstructure Design Criteria

BUILDING REGULATION

• The Building Act 1984 is the primary piece of legislation that formed the Building Regulations and their Approved Documents.
• The Building Act 1984 is an overarching legislation that provides the legal framework for building and construction activities.
• Building regulations are minimum standards for design, construction and alterations to virtually every building. The regulations are developed by the UK government and approved by Parliament.
• Compliance with Building Regulations is mandatory, and failure to adhere to these standards can result in legal consequences.

• Approved Documents set out detailed practical guidance on compliance with the regulations: (Set into a whole range of subsections: Parts A-S).
• The Building Act covers some of the following provisions:
• Power to make the Building Regulations and any subsequent revisions.
• Production of Approved Documents
• To allow the passing of submitted plans.
• To give powers to inspectors.
• Penalties for breaches to the regulations.

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Superstructure Design Criteria

SITE ACESS

• Material Delivery and Handling: Limited or challenging site access may restrict the delivery and handling of construction materials. Designing components that are modular or can be easily transported and assembled on-site can mitigate these challenges.
• Logistics and Storage: The availability of space for temporary storage of materials and equipment can impact the design. Superstructure elements may need to be designed to allow for efficient storage and staging during construction.
• Crane Access: The availability of space for crane positioning and operation is crucial for lifting and placing heavy structural elements. Complex or congested sites may require specialized lifting solutions or adjustments to the design to accommodate the lifting equipment.
• Safety Considerations: Limited site access can present safety challenges. Designing superstructures with safety in mind, including provisions for worker access, emergency egress, and fall protection, becomes crucial.
• Utilities and Services: Accessibility for the installation and maintenance of utilities and services, such as plumbing, electrical, and HVAC systems, needs to be factored into the superstructure design.

Self-assessment Task

Explain any THREE design criteria for superstructure.

Relate your explanation to iconic buildings in Wales or the United Kingdom.

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1. Weather exclusion
2. thermal insulation
3. Provide ventilation
4. Heat reflection
5. Sound insulation
6. Provide access and egress
7. Prevent moisture penetration
8. Fire resistance
9. Security and safety
10. Visual contact with outside
11. Load bearing capacity

Superstructure – Functional Characteristics

Figure 7. Primary functions of superstructure (Chudley and Greeno, 2016)

Durability

• The durability of walls is closely tied to the level of weather exposure in a given location.
• Moisture infiltration can lead to varying degrees of dampness on the inner surface of the wall.
• Major sources of dampness include moisture rising from the ground, rain penetration, and infiltration around openings.
• Strategies to prevent moisture passage through or along external building walls include:
• Employing a completely impervious barrier, such as curtain walling, cavity tray, damp-proof courses (DPC) around window and door openings.
• Creating walls with a cavity to act as a barrier that moisture cannot bridge.

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Wall – Functional Characteristics

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Sound Resistance

Fire resistance

• Fire performance of walls comprises two elements:
• Surface Spread of Flame: Materials ideally should not contribute to the spread of flame across their surface.
• Inherent Fire Resistance: (Stability, Integrity, Insulation)This aspect can be compromised when:
• The wall collapses during a fire.
• Fire breaches a section of the wall.
• The heat insulation properties of the wall are compromised.
• Ensuring both elements are addressed is crucial for effective fire performance in walls.

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Wall – Functional Characteristics

• No construction material or method can claim absolute fireproofing; hence, specified periods of fire resistance are assigned to particular building applications in specific contexts.
• Minimum fire resistance durations differ for load-bearing walls, ranging from 30 to 120 minutes (Welsh Government, 2021).
• Internal walls may necessitate fire resistance, especially in scenarios like designated fire escape routes, safeguarded shafts (lifts, staircases), compartment walls segregating diverse usage spaces, and load-bearing walls.

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Climate Control:

Roof Ventilation Systems: Ridge vents, soffit vents, or other ventilation components that allow the exchange of air, helping to regulate temperature and humidity.

Moisture Resistance:

Roofing Underlayment: Material installed under the roof covering to provide an additional layer of protection against moisture penetration.

Flashing: Metal strips or sheets installed at joints, valleys, and intersections to prevent water infiltration.

Roof – Functional Characteristics

Resistance to Wind Load:

Roof Sheathing: Plywood or oriented strand board (OSB) panels that, when properly installed, add structural strength and resistance to wind forces.

Roof Trusses/Rafters: The framing elements that support the roof and help distribute wind loads evenly.

Figure 8. A roof section.

Load Transmission:

Roof Framing: This includes rafters or trusses that transfer the load of the roof covering, snow, and other elements to the building's structure.

Sound Barrier:

Insulation Materials: Some insulation materials can contribute to sound absorption, providing a degree of noise reduction within the structure.

Durability:

Roof Covering Materials: Durable materials such as asphalt shingles, metal roofing, tile, or slate that provide protection and longevity.

Roof – Functional Characteristics

Figure 8. A roof section.

Thermal Barrier:

Roof Insulation: Material installed within the roof structure to resist the transfer of heat, providing a thermal barrier for climate control and energy efficiency.

Floor – Functional Characteristics

Floor performance necessitates meeting various criteria, including:

• Serving as a physical barrier, 
• Bearing required loads, 
• Controlling sound transmission, 
• Minimising thermal transmittance, 
• Preventing the spread and penetration of fire, 
• Resisting structural impact, 
• Accommodating openings and penetrations, 
• Minimising deflection,  
• Providing support to other structural elements.

Stability

• Stability considerations for suspended timber upper floors involve
• Spanning from wall to wall with increased depth to minimize twisting.
• Strutting is employed to further reduce twisting and lateral movement of the joists.
• The stability of the floor surface is influenced by the spacing of joists and the type of board or sheet material used. Check this. 

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Floor – Functional Characteristics

Sound insulation

• In scenarios requiring sound insulation, such as in multiple occupancy settings like flats, a soundproofing approach involves constructing a new ceiling with two layers of plasterboard supplemented by layers of mineral wool and a floating insulation layer.

Figure 9. Floating floor (Welsh Government, 2022)

Floor – Functional Characteristics

Concrete floors exhibit characteristics in various aspects:

Fire Resistance: Concrete experiences a progressive loss in strength when exposed to temperatures exceeding 120 degrees Celsius, with rapid failure ensuing once its cover is lost.

Sound Insulation: Concrete provides good resistance to airborne sound, thanks to its mass's ability to absorb sound energy. However, its resistance to structure-borne sound is comparatively poorer.

Addressing Structure-Borne Sound: Mitigating structure-borne sound can be achieved through the incorporation of resilient layers and floating screeds

• Fire protection for floors is determined by their height in relation to the adjacent ground (Welsh Government, 2021, p. 126).
• For fire protection, 12.5mm plasterboards are affixed to joists using 60mm galvanized nails at 600mm centres, with additional support from nails spaced 150mm apart.

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Figure 10. Floor (Chudley and Greeno, 2016)

Fire resistance:

• Fire resistance measures may include applying plasterboard to the underside of stairs for slight protection.
• Timber stairs within a protected fire escape route in multiple-occupancy properties receive enhanced fire protection.

Structural stability

• Concrete stairs maintain a 25 mm depth of cover to the reinforcement during casting to preserve strength.

Sound resistance and Thermal insulation

• Use of soft covering, and plasterboards to which are added layers of mineral wool.

Access & Egress

• Doors are restricted from opening onto landing positions, except for cupboard or access duct doors or at a bottom landing, where a clear space of 400 mm across the width of the landing must be maintained in all cases.

Stairs – Functional Characteristics

Figure 11. Stairs (Welsh Government, 2022)

• These include wall finishes (rendering, plastering, dry lining, painting, etc.), cladding (curtain walling, rainscreen, brick slip, timber, stone, etc.), floor finishes (ceramic, concrete, terrazzo, carpet, etc.), skirting boards, decoration, etc.
• They provide:
•  Acoustic conditioning, 
• Thermal insulation, 
• Fire resistance,
• Size reduction of rooms, 
• Concealing imperfections, 
• Protection from impact, water, frost, corrosion, and abrasion,
• Serve aesthetic functions.

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Finishes – Functional Characteristics

Self-assessment task

• Explain any THREE functional characteristics for the primary and secondary elements of a superstructure.

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• Explain how any two primary and two secondary elements meet the range of performance requirements identified above. (Hint: refer to the Building Regulations).

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Reference/Bibliography

Asia Tents Manufacturing (n.d.) Tensile membrane structures. Available at: https://www.asiatentsmanufacturing.com/tensile-membrane-structures (Accessed: 24 November 2023).

Chudley, R. and Greeno, R. (2016) Building construction handbook. 11^th edn. London: Routledge.

Designing Buildings Ltd. (2023) Finishes. Available at: https://www.designingbuildings.co.uk/wiki/Finishes#:~:text=Finishes%20are%20used%20in%20the,or%20they%20can%20be%20decorative. (Accessed: 23 November 2023).

Fidanci, E. A. (2023) Golden ratio samples in architecture. Available at: https://illustrarch.com/articles/15613-golden-ratio-samples-in-architecture-1.html#:~:text=The%20United%20Nations%20Secretariat%20Building%20in%20New%20York%20City%20is,related%20to%20the%20Golden%20Ratio. (Accessed: 26 November, 2023).

Keaney, D. (2017) Sound insulation testing Ireland [YouTube]. Available at: https://www.youtube.com/watch?v=bsmLYk47OOg&t=266s (Accessed: 23 November 2023).

NHBC (2023) NHBC standards. Available at: https://www.nhbc.co.uk/binaries/content/assets/nhbc/tech-zone/nhbc-standards/nhbc-standards-2023-complete-compressed.pdf (Accessed: 09 November 2023).

The Taunton Press (2017) Insulated concrete forms: the perfect choice for energy-efficient construction. Available at: https://www.finehomebuilding.com/sponsoredpost/2017/10/30/insulated-concrete-forms-perfect-choice-energy-efficient-construction (Accessed: 26 November 2023).

Welsh Government (2019) Approved document a: Structure. Available at: https://www.gov.wales/sites/default/files/publications/2019-04/170403building-regs-approved-document-a-structure-en.pdf (Accessed: 09 November 2023).

Welsh Government (2021) Approved document b. Available at: https://www.gov.wales/sites/default/files/publications/2021-12/building-regulations-guidance-part-b-fire-safety-volume-1-dwellinghouses.pdf (Accessed: 24 November 2023).

Welsh Government (2022) Approved document e. Available at: https://www.gov.wales/sites/default/files/publications/2022-04/building-regulations-guidance-part-e-resistance-passage-sound.pdf (Accessed: 24 November 2023).

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