Last edited 02 Feb 2015

Detailed design stage in building design

Detailed design is sometimes referred to as 'developed design' or 'definition'. It is the process of taking on and developing the approved concept design.

By the end of the detailed design process, the design should dimensionally correct and co-ordinated, describing all the main components of the building and how they fit together. However, technical aspects of the design may require further development, design by specialists may not yet have been fully incorporated into the design and it will not have been packaged for tender.

Detailed design should provide sufficient information for applications for statutory approval to be made.

Detailed design should include:

  • Overall layout.
  • Road layouts and landscape.
  • Operational flows and departmental operational policies.
  • Horizontal and vertical circulation routes, including accessibility requirements.
  • Schedules of accommodation, including occupancy numbers for each space.
  • Identification of standard and non-standard room layouts.
  • If appropriate, room data sheets.
  • Building dimensions and gridlines.
  • Architectural plans sections and elevations of buildings, parts of buildings and components, including:
  1. Block plans.
  2. Site plans and external works.
  3. Changes in floor levels.
  4. Expansion joints.
  5. Demarcation of changes to finishes.
  6. Reflected ceiling plans.
  • Outline specification including schedules of components, defining the performance and/or material standards required (including colours).
  • Elements of design that require specialist input or early choice of manufacturer. Designers should investigate suppliers certificates, warranties and compliance with standards.
  • Requirements for mock-ups, testing, samples or models necessary to satisfy performance or public relations requirements (including computer generated images).
  • Key assemblies, component drawings and schedules with special attention to junctions and interfaces between elements which will influence the structural or services designs or have an effect on the spatial allowances. Key details will include:
  1. External walls, lining, cladding, glazing, windows and blinds.
  2. Balconies, canopies and entrances.
  3. Roofing and finishes, rooflights, drainage, gutters and outlets.
  4. Floor constructions and finishes.
  5. Staircases.
  6. Damp proof courses.
  7. Service duct and services plan enclosures.
  8. Load bearing internal walls and partitions, including lifts and other shafts.
  9. Non-load bearing partitions.
  10. Ceiling construction and support.
  11. Overall dimensions and fixing details for fixed equipment such as sanitary fittings and joinery.
  12. Roads, paths, paving, boundaries and retaining walls.
  13. External gradients and falls including gutters and outlets.
  14. Components that can be standardised, mass produced or prefabricated, resulting in reduced costs or reduced construction durations.
  • Initial schedules indicating:
  1. Finishes.
  2. Doors and ironmongery.
  3. Sanitary fittings.
  4. Room numbers and signage.
  1. The location of all structural elements in relation to gridlines.
  2. Dimensions and sizes of beams, columns, walls and slabs.
  3. Sketch details of junctions and proposed fixings.
  4. Superimposed loading allowances for each floor slab.
  5. The proposed discipline for all holes giving range and sizes permissible.
  6. An outline specification including total weights of reinforcement.
  7. The detailed design should highlight any changes from the concept design and provide the services engineer with sufficient information to undertake the services design.
  1. Plumbing and drainage (high and low level).
  2. Ductwork.
  3. Heavy pipework.
  4. Electrical trunking.
  5. Light pipework.
  6. Electrical control wiring.
  7. Radiators.
  8. Plantroom layouts.
  9. Riser drawings.
  10. Access requirements and builders work in connection.
  • Define phases if the project is to be phased. This can be complicated by items that appear in buildings intended for later phases, but that are required for the operation of earlier phases, for example boilers or escape stairs.
  • Safety strategy.
  • Fire strategy, including:
  1. Zoning and compartmentation.
  2. Separation (such as fire resistance of compartments, restriction of openings between compartments and distances to boundaries).
  3. Protected shafts (staircases and services).
  4. Surface spread of flame and escape strategy (including travel distances and staircase widths).
  5. Active measures such as detection, ventilation, alarms, sprinklers.
  6. Minimum ventilation requirements where no mechanical ventilation is provided.
  7. Dry risers and hose reels.
  8. Uninterrupted power supplies.
  9. Fire rated cables.

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