T2. CONSTRUCTION TECHNOLOGY & ENVIRONMENTAL SERVICES Flashcards
What is substructure?
- All elements of work that are undertaken below the damp proof course that provides the basis for the superstructure to be constructed upon.
What is the external envelope?
- The materials and components that form the external shell or enclosure of a building.
- These may be load or non-load bearing.
What are the Building Regulations?
- Statutory instruments that set out the minimum performance standards for the design and construction of buildings.
- Supported by the Approved Documents and other codes of practice.
What are the approved documents?
Approved Documents provide guidance on complying with Building Regulations 2010.
They are:
A. Structure.
B. Fire safety.
C. Site preparation and damp proofing.
D. Toxic substances.
E. Sound proofing.
F. Ventilation.
G. Hygiene.
H. Drainage and waste disposal.
I. Not in use.
J. Heating appliances.
K. Protection from falling, collision and impact.
L. Conservation of fuel and power.
M. Disabled access and facilities.
N. Glazing.
O. Not in use.
P. Electrical safety.
What are British Standards?
- Publications issued by the BSI prefixed BS.
- Give recommended minimum standards for materials, components, design and construction
practices.
What are international standards?
- Publications issued by the International Organisation for Standardisation – prefixed ISO.
- They are compatible with and complement the British Standards.
What is superstructure?
- All internal and external works items above the damp proof course.
- This is made up of:
o External walls.
o Stairs.
o Roof.
o Structural walls.
o Suspended ceilings.
o Raised floors.
What are the typical components of site investigations?
- Their objective is to collect and record data to help with the design and construction process. This includes matters in relation to the site that may impact the development for example:
o Size, depth and location of services including gas, telephone, electricity, water & drains.
o Existing buildings.
o Ground water conditions.
o Soil investigations.
o Trial pit information.
o Boundary hedges & fencing.
o Existing trees.
What is the purpose of soil investigations?
- To determine the suitability of the site for the proposed works.
- To determine adequate and economic foundation design and identify a suitable foundation solution.
What are the main site considerations?
- Access considerations.
- Storage considerations.
- Accommodation.
- Temporary services.
- Plant.
- Fencing & hoarding.
- Health & Safety risks.
What is a retained façade?
- The façade of the building is retained whilst everything behind the front wall is demolished.
- Allowances needs to be made for a temporary support structure and also cleaning & restoration works to the retained façade.
- Retained facades are often required as a result of listed building requirements.
What are temporary works?
- Temporary works do not normally appear on construction drawings but may be required depending on the construction methodology being used.
- Temporary works may also be required as a result of health and safety requirements to ensure a safe method of construction for example temporary propping.
What is a tower crane and what are some considerations during its erection and operation?
- A tower crane is a tall crane used for lifting objects into high places.
- The boom allows a longer reach with 360 access.
- A longer boom reduces the payload capability.
- You would usually use a smaller crane to erect a tower crane.
- Weather conditions could prevent it from working, in particular high, strong winds.
What is a scaffold?
- Scaffold is a temporary working platform erected around the perimeter of a building or structure to
provide a safe working place at a convenient height. - Scaffold is usually required for work 1.5m above ground level.
What is shoring?
- Shoring is a form of temporary support given to existing buildings.
- Its purpose is to provide a precaution against damage or injury due to collapse of the structure.
What are the main components of concrete?
- Cement.
- Aggregate (natural rock, crushed stone, gravel).
- Water.
What is a borehole?
- A borehole can be used for soil investigation or for geothermal heating solutions.
- Boreholes are the most suitable method of soil investigation when foundations are over 3m deep.
- Geothermal boreholes are permanent boreholes that use the Earth’s natural heat to raise the temperature of circulated water.
- This is a closed system and can be used to heat the building above which is adopted as a sustainable technology.
What are piles?
- A series of columns constructed or inserted into the ground to transmit the load of a structure to a lower level of subsoil.
- They are used where no suitable foundations conditions are present near ground level or if there is a high water table.
What are Sheet piles?
- Sheet materials with interlocking edges.
- Driven into the ground to provide earth retention and excavation support
- Most commonly made of steel, but can also be formed of timber or reinforced concrete.
What are Secant piles?
- Interlocking piles (male and female, often different diameters and hardness) are bored to provide a combination of foundations and basement walls.
- They support in providing a waterproof structure and are often seen when a top down construction method is used.
What are Bored piles?
- An auger is used to excavate the soil and then concrete is poured in once complete.
What are Pre-cast piles?
- Driven precast piles are installed using impact or vibration hammers.
- Suited to thick layers of soft soil and/or a high water table which may be problematic for bored.
- Method not favourable due to the high noise levels associated with installation and the lack of flexibility in terms of depth required.
What are the different ways that the piles transfer their load to the surrounding ground?
- End bearing piles – Transfer load through weak soil to a strong stratum, such as rock or dense sand.
- Friction piles – Rely on friction between their surface and the surrounding soil for load transfer.
What is the difference between bored vs. driven piles?
- Bored piles: Excavated and poured in situ, ideal for cohesive soils and low-noise/vibration areas near buildings.
- Driven piles: Hammered or vibrated into the ground, suitable for offshore use, soft soils, and soil densification but unsuitable for developed areas.
What are the problems to the PQS regarding cost control with piling and who owns the risk?
- The end depth of the piles are never certain and the procurement route used determines who takes the risk.
- For example under a traditional or design & build procurement the main contractor would normally take risk ownership whereas under management contracting the risk would remain with the employer.
What is a raft foundation?
- A raft foundation is a large concrete slab that evenly distributes a building’s load over a wide area, covering its footprint.
- Raft foundation solutions are useful in low bearing capacity soils.
Under what conditions would you expect a raft foundation to be used for a substructure?
- A raft can be used for lightly loaded buildings on sites with poor soils.
- Heavy loads to the raft have the potential to cause the raft to move sideways as a result of raft foundations not being very deep.
What is a strip foundation?
- Provides continuous support for linear structures such as walls.
- Suitable for most subsoils and a light structural design.
What are pad foundations?
- Pad foundations provide a base for reinforced concrete or steel columns.
- They are usually formed by making an isolated excavation in the shape of a square or rectangle.
- They often have reinforcement mesh as part of the construction and spread the load to a layer of bearing soil or rock below.
What are retaining walls?
- Walls that provide lateral support to retain soils.
What are the main types of excavation for forming basements?
- Open excavations that use battered excavation sides which are cut back to a safe angle. This eliminates the need for temporary earth work support and can be used to construct basement walls. This requires additional excavation costs and significant working space when compared to other methods.
- Perimeter Trench Excavation can be used to form basement walls. This method requires earthwork
support with the basement walls being constructed and then the inside of the basement is excavated. - Complete Excavation can be used in firm subsoils. The Centre of the basement is excavated first, then the basement slab cast while the sides of the excavation are supported by struts.
What legislation and regulations influence building design?
The primary legislation influencing building design in the UK is the Building Regulations 2010 (as amended), which ensure buildings are safe, accessible, and sustainable. Compliance is mandatory,
Other influences include the Health and Safety at Work Act 1974, planning regulations, and specific sector requirements like HTM’s HBN’s on healthcare projects.
What is the Building Safety Act 2022?
Legislation introduced following the Grenfell disaster and subsequent Hackitt report.
Act intends to secure safety of people and improve the standard of buildings.
What is the definition of an HRB under the act?
An HRB is a High Risk Building. An HRB is any building that is greater than 18 metres or 7 storeys high and contains 2 or more residential units. Also includes care homes and hospitals but excludes some buildings including hotels, military barracks and prisons.
What significant changes came out of the BSA 2022?
- Introduction of new Duty Holder regime
- Introduces specific provisions for HRB’s
- Introduction of the BSR which regulates all HRB’s
Who is the Building Safety Regulator?
The BSA names the HSE as the new BSR
Who can act as building control for non-HRB’s?
Other building control bodies including local authorities and registered Building Control Approvers
On which HRB projects will the new Building Control process apply?
- Construction of new HRB’s
- Construction work to existing
- Work that causes non HRB to become HRB (change of use)
*Work that causes HRB to become non-HRB
Who are the new duty holders?
- Client - Must be satisfied that appointed PD & PC have necessary skills, knowledge and experience to fulfil duties in relation to designing/building work.
- Principal Designer - Plan, manage and monitor design work during design phase.
- Principal Contractor - Plan, manage and monitor building work during construction phase.
What are the Accountable Persons duties?
An AP must be appointed during the occupation phase to manage the fire and structural safety of an HRB.
Must report safety issues to BSR.
Must maintain ‘Golden Thread’ information.
Who are the additional duties placed on duty holders in relation to HRB’s?
Duty holders must issue competence and compliance declarations.
Duty holders must be appointed BEFORE Building Control approval is submitted (non-HRB’s before construction phase).
An accountable person must be appointed during the occupation phase.
What is the Golden Thread?
A digital record of all important building information throughout a buildings life cycle (i.e. design, construction and maintenance information)
What are the new BSA Gateways for HRB’s?
Gateway 1: Planning approval – ensuring fire safety is part of planning permission
Gateway 2: Construction approval – where work can only start after BSR building control approval
Gateway 3: Completion approval – where the higher-risk building must pass BSR checks before occupancy
What is MMC?
Modern methods of construction
What different forms of MMC are there?
Forms of MMC vary from the offsite manufacturing of materials in a factory environment, to full 3d volumetric buildings constructed off site
What are the benefits of MMC?
Speed of construction
Improved quality control
Cost efficiency (reduced labour costs)
Sustainability
Safer method of working (more work completed off site)
What are the limitations of MMC?
Manufacturers/suppliers often have high overheads due to the factory led approach. Can increase cost.
Lack of design flexibility, particularly with modular or volumetric construction
Logistical challenges
In what circumstances would you recommend MMC to a client?
If the client was looking for a fast efficient and sustainable method of construction. Provided it was a simplifies building
How can MMC affect the timeframes of a construction project?
Accelerate construction phase as manufacturing can occur whilst works commence on site
How can MMC affect the cost of a construction project?
Varies. Many claim that MMC is more expensive but savings can be made from reduction of programme duration i.e. prelims.
How can MMC affect the quality of a construction project?
Manufacturing approach can enhance quality of construction. Not reliant on variables such as trade labour
What is a lightweight SFS structure?
A lightweight steel framing system used in the construction of walls, floors, and roofs.
It typically involves cold-formed steel sections that are fabricated off-site and assembled on-site.
Often used for non-load bearing walls or secondary framing
What is a steel frame structure?
A steel frame structure is a load-bearing framework of steel columns, beams, and girders that form the skeleton of a building.
What are the key differences between a lightweight SFS structure and a steel frame structure?
Purpose
Lightweight SFS: Primarily used for non-load-bearing walls and partitioning.
Steel frame: Used for load-bearing frames, supporting floors and roofs.
Material
Lightweight SFS: Cold-formed steel sections, often smaller and lighter.
Steel frame: Hot-rolled steel sections, stronger and bulkier.
Weight
Lightweight SFS: Lightweight compared to traditional steel framing.
Steel frame: Heavier due to larger steel sections.
Flexibility
Lightweight SFS: Easier to work with for smaller-scale, non-structural applications.
Steel frame: Used for larger structures, offering more structural flexibility.
Application
Lightweight SFS: Walls, partitions, and cladding in low-rise buildings.
Steel frame: Primarily used in high-rise buildings, industrial buildings, and large-scale structures.
What are the advantages of a lightweight SFS structure?
Buildability: Maximum off site fabrication, easier to handle and transport, reducing labour and transportation costs.
Speed of Construction: Faster assembly due to pre-fabricated components and lighter materials.
Foundations: Lower structural load, reducing the need for extensive foundations.
Cost-Effective: Lower material and labour costs compared to heavier steel framing.
What are the disadvantages of a lightweight SFS structure?
Acoustics: Relatively poor acoustic separation
Fireproofing: Requires full fire boarding to floor soffit and columns
Futureproofing: Not suitable for load-bearing applications as the structure cannot support heavy loads. Unable to withhold new AHU and therefore limited futureproofing.
What are the advantages of a steel frame structure?
Acoustics: Comparatively better acoustic separation
Fireproofing: Concrete slab inherently fire resisting to 60 mins
Futureproofing: Capable of supporting heavy loads. Load capacity is available for ward and operating theatre and x-ray room
Flexibility in Design: Allows for larger open spaces and fewer load-bearing walls, which can lead to more design flexibility.
What are the disadvantages of a steel frame structure?
Higher Cost: Steel frames are more expensive due to the materials and fabrication processes involved.
Buildability: Metal deck would mean increased manual labour on site. Wet trade: pouring of concrete.
Foundations: Requires more robust foundations due to the weight of the frame.
Provide some examples of the different substructure designs you have encountered on construction projects?
Piled foundations (Barnet ED/Elective Hub), pad foundations (Staff Wellbeing), strip foundations (resi housing)
What type of piled foundation was used on Project Elective Hub?
Continuous flight auger (CFA) bearing piles
Why were piled foundations used on Project Elective Hub?
Due to the soil bearing capacity and to provide lateral support due to sloping ground level
What are the features of difference piling methods
Bored: Cylindrical hole drilled to required depth. Soil removed. Reo placed and concrete poured. Suitability: Clays/loose sands and urban applications (minimise soil disturbance)
Driven: Installed using impact of vibration hammers. Suitability: Dense soils and offshore applications
CFA: Similar to bored pile, however concrete is poured simultaneously. Reo inserted into wet concrete. Suitability: Average depths, urban areas and environmentally sensitive sites.
Secant piles: Uses overlapping concrete piles to create a retaining wall. Primary piles are installed first; Secondary piles are installed in between the primary piles, cutting into them; The overlapping piles create a continuous barrier to water and soil. Suitability: Deep excavations, forming retaining wall; high water table
How does a top-down basement construction differ to a conventional basement?
Execution of diaphragm walls
Piles inserted
Ground slab construction
Excavation of basement floors commences
How does the top-down method minimise disruption?
Diaphragm walls and formation of ground slab minimise noise during construction of the rest of the basement
More controlled excavation reduces vibration and the risk of damage to neighbouring buildings
How do late design changes affect modular construction projects?
Late design changes are costly. A modular construction projects are factory led, they must go through various stages of design freeze in order to be manufactured.
Why did the identification of time as a key driver influence your decision to recommend modular?
Modular construction can accelerate the works on site as the structure is manufacturer whilst substructure works on site progress, thereby reducing the overall construction period.
How would your advice have changed if the client’s key driver was cost?
My advice would not necessarily have changed but I would have suggested undertaking a design appraisal to see whether modular or traditional construction would have delivered better value.
How would your advice have changed if the client’s key driver was quality?
I would have advised the client that with modular there are fewer variabilities that can impact the quality of the building.
What do you understand by the term Value Engineering?
Aims to achieve necessary functions of a building project at a lowest cost.
When is VE used?
When early cost plans or tender returns are over budget.
How did you go about Value Engineering Project Roof Garden?
I arranged a meeting with the client and the design team to brainstorm. Value engineering is a collaborative approach
Were any other VE proposals tabled on Project Roof Garden?
Yes, an alternative balustrade was proposed changing this from glazed to steel and the lighting specification was changes
What is VM?
Broader process of maximizing the overall value of a project by aligning stakeholder needs and objectives throughout the project lifecycle.
Is VE the same as VM?
No but VE is a specific technique which come under the umbrella of VM
On Project Esher Wing Atrium, what were the cost implications of using a lightweight SFS structure instead of a steel frame with composite concrete floors on metal decking?
Lightweight structure was more cost-effective; lower material and labour costs compared to heavier steel framing.
Steel frames are more expensive due to the materials and fabrication processes involved.
On Project Esher Wing Atrium, what were the programme implications of using a lightweight SFS structure instead of a steel frame with composite concrete floors on metal decking?
Both structures quick to erect however lightweight was advantageous as it did not require extensive foundations.
On Project Esher Wing Atrium, what were the construction implications of using a lightweight SFS structure instead of a steel frame with composite concrete floors on metal decking?
Steel frame and concrete floor would require wet trade. Pouring of concrete will require pumping and partial downtime on corridor whilst pump is in use. This could temporarily impact means of escape in an High Risk Building.
