Code of Practice for Demolition of Buildings – PRECAUTIONARY MEASURES

  1. General

Site safety features shall emphasise protection of the public, particularly, the pedestrian and vehicular traffic and the adjacent properties. Proper safety features shall be designed by the Authorized Person / Registered Structural Engineer to make sure that the demolition can be carried out safely and the site personnel is protected. The Registered Specialist Contractor (Demolition) shall carry out the demolition works including precautionary measures in accordance with the approved plans and other related documents, and provide continuous supervision to the works.

Code of Practice for Demolition of Buildings – Soil Contamination Material

  • Soil Contamination Material

In the case when possible soil contamination material is present, specialist shall be employed to prepare soil contamination test proposal and submit such proposal to the Environmental Protection Department for comment. Upon agreement by the Environmental Protection Department, and completion of the tests, a Soil Contamination Assessment shall be submitted to the Environmental Protection Department for acceptance. In the case when remedial works are required, the remedial proposal shall be submitted to the Environmental Protection Department for approval prior to implementation of such remedial works.

Code of Practice for Demolition of Buildings – Asbestos Containing Material

  • Asbestos Containing Material

Specialists shall be employed to take samples and cause such samples to be tested for asbestos containing material. In the case when asbestos containing material are discovered, specialist contractor shall be employed to remove such asbestos containing material. The asbestos

waste should be handled, stored and disposed of as chemical waste in accordance with the Waste Disposal Ordinance and Waste Disposal (Chemical Waste) (General) Regulation.

Code of Practice for Demolition of Buildings – Hazardous Material

  1. Hazardous Material

If hazardous materials, such as asbestos containing materials, petroleum contamination and radioactive contamination, exist in the building, further investigation and removal of such hazardous material or contamination by specialist shall be referenced.

Code of Practice for Demolition of Buildings – Maintenance of Certain Utilities

  • Maintenance of Certain Utilities
  • During demolition, the following basic utilities shall be required to provide a safe and healthy working environment:
    • Temporary water supply shall be required to provide water spraying during demolition as dust pollution abatement measures;
      • Temporary telecommunication link between the demolition site and outside organisation shall be maintained for both security and communication reasons; and
      • Temporary electricity supply for lighting and other construction use.
  • In the case when temporary utilities are available, all such temporary utilities, including electrical fittings shall be weather-proofed.

Code of Practice for Demolition of Buildings – Common Utilities

  • Common Utilities

The common utilities encountered in building demolition generally include the following:

  • Electricity;
  • Water;
    • Gas;
    • Telecommunication;
    • Drainage;
    • Overhead and Underground Cables;
    • Railway Tunnel and its accessories, such as vent shafts;
    • Sewage Tunnel and its accessories; and
    • Disused Tunnel.

All utility companies and relevant agencies shall be consulted prior to demolition of the structure.

Code of Practice for Demolition of Buildings – Effects of Demolition on Utilities

  • Effects of Demolition on Utilities

The demolition plan shall ensure that during the course of demolition, no existing utilities in the vicinity of the demolition sites are affected by the demolition operation.

Code of Practice for Demolition of Buildings – Termination of Utilities

  • Termination of Utilities

Prior to actual demolition, the Authorized Person shall liaise with all available utility companies so as:

  • to keep records of available utilities leading into the premises; and
    • to cause all utilities to be terminated.

Code of Practice for Demolition of Buildings – Demolition Plan and Stability Report including Calculations

  • Demolition Plan and Stability Report including CalculationsDemolition Plan

A Demolition Plan shall include the following :

  • A plan showing :
    • the location of the building to be demolished;
      • a detailed topography of the site and its surrounds together with ground level contours and sections of the slopes and ground supported by the building where appropriate;
      • details of ground removal and/or backfilling; and
      • the distances from the building to be demolished to its adjacent buildings, streets, structures and significant street furniture.
  • A layout plan of all floors of the building to be demolished, with adequate sections, showing :
    • the occupancy usage of the floors;
      • the structural support systems;
      • principal materials of construction;
      • the condition of the building e.g. the degree of deterioration; and
      • the relationship of the building to be demolished with neighbouring properties affected by the demolition, which include all adjoining buildings and unauthorized structures, shared staircases, party walls, truncating continuous frames, slopes, retaining wall, overhead cables, guy wires and underground utility services.
  • A plan showing the structural arrangement and construction of all unconventional structural elements, such as prestressed concrete structures, precast concrete members, stressed skin structures, steel framed structures, hangers, hanging ties, trusses or Vierendeel girders, deep beams, long span beams (greater than 10m), arches, transfer plates, transfer girders, earth retaining or basement structures, buildings which also act as earth-retaining structures supporting adjacent ground, flat slabs, hollow block ribbed slabs and large cantilevered structures;
    • A plan showing the procedure for the demolition of the building; detailed sequence of demolishing particular structural members; and the method of demolition to be adopted including the restrictions on the use of any particular type of equipment;
      • In the case when powered mechanical plants and equipment are used, a plan showing the route of movement of powered mechanical plants and equipment including the method of lifting mechanical plant, where necessary, onto the top floors of the structure; any structural alterations required to suit the demolition, e.g. temporary strengthening to suit early removal of any ground floor/or cockloft structure to facilitate vehicular movement at ground floor, or strengthening of deteriorated key structural members; and any shoring, temporary supports and/or floor propping required;
  • A plan showing all precautionary measures for the protection of the public including hoardings, covered walkways, catch platforms, catchfans, scaffolding, protective screens and safety nets;
  • A plan showing the proposed shoring and precautionary measures for all affected adjacent buildings, slopes, retaining structures and services at each stage of the demolition works;
  • A plan showing the proposed shoring and temporary support to be provided to the building to be demolished;
  • A plan or descriptive notes on the proposed methods for handling and disposal of debris including :
  • the permissible temporary accumulation of building debris at upper floors and at ground floor;
    • method of handling demolished building debris;
      • the routing and movement of debris from each floor to on grade holding area prior to leaving the site;
      • means of transportation of debris off the site;
      • time and frequency of debris disposal off site;
      • record scheme on the tonnage of each truck load, truck licence plate, driver’s name, trip tickets and location of dump site;
      • the site supervisory personnel responsible for the debris management system; and
      • a temporary parking layout for mobile machines and trucks, if necessary;
  • Stability Report including Calculations

According to Building (Administration) Regulation 8(4), the Demolition Plan must be accompanied by a Stability Report with supporting calculations. The Stability Report shall include the following parts :

  • a report on the stability of the building to be demolished during all stages of demolition;
  • in the case when powered mechanical plants or equipment are used, a report on the stability of the building with supporting calculations to demonstrate that the use of the plants and equipment will not render inadequate the margin

of safety of, or cause damage to any building, structure, street, land and services;

  • in the case when powered mechanical plants or equipment are used, structural calculations for all temporary supports and bracings;
  • a report on the stability of neighbouring buildings, adjoining properties as stated in 2.1.1.(B)(5), party walls, streets, land and services which may be affected by the demolition work;
  • in the case when temporary or permanent supports are required to these neighbouring buildings, adjoining properties, and party walls, structural calculations for these temporary and permanent supports; and
  • a report with calculations demonstrating that the demolition work will not render inadequate the margin of safety of, or cause damage to any building, structure, street, land and services.

A checklist for preparing a Demolition Plan and Stability Report with Calculations is depicted in Appendix B.

Code of Practice for Demolition of Buildings – Structural Survey

  • Structural Survey
  • Record Drawings

Prior to the Structural Survey, the existing record layout, structural framing plans and structural details shall be studied. The Registered Structural Engineer shall check the presence of unusual detailing that may cause abnormal structural behaviour during demolition, e.g., upward anchor of tensile reinforcement in cantilevered structures. If existing record plans are available, these plans shall be used as reference and preferably be brought along with the Structural Survey.

  • Survey Items

The Structural Survey shall cover the following:

  • The structural materials used;
    • The original structural system employed in the design;
      • The method of construction;
      • Any dilapidation and degree of deterioration on any structural elements;
      • The structural conditions of adjoining structures and its shoring which may be affected by the proposed demolition work;
      • The presence of continuous structures that may be truncated by the demolition;
      • The structural system and structural conditions of basements, underground tanks or underground vaults;
      • The presence of exposed bracing or possible presence of covered bracing;
      • The nature of walls, whether it is blockwall, reinforced concrete walls, load bearing walls or partition walls;
      • Cantilevered structures such as canopies, balconies, or other forms of architectural features; and
      • Any fixtures to the building such as signboard, sun-shading devices.
  • Special Structures

The Structural Survey shall review the following :

  • the correctness of structural information available;
    • the presence of any unconventional structural elements referred to in 2.1.3(A)(3) which may require special attention and well-defined modification procedures;
      • the possibilities of structural modification to enable efficient demolition traffic during demolition; and
      • any limitation on shoring and other temporary supports.
  • Investigation and Testing

In the case when no structural details are available, the Structural Survey shall include on site measurement and retrieve any structural framing as much as practicable, performing tests and exposing some key structural elements to facilitate checking on existing structure. This will allow the development of procedures that ensure the stability of the building at all stages during demolition.