Tag Archives: Code of Practice for Demolition of Buildings

Code of Practice for Demolition of Buildings – Common Utilities

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  • 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

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  • 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

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  • 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

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  • 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

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  • 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.

Code of Practice for Demolition of Buildings – Building Appraisal and Demolition Plan

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  1. Building Appraisal and Demolition Plan

Prior to carrying out any building demolition, detailed building appraisal by means of surveys and appropriate assessments shall be required. In general, the surveys shall include a Building Survey and a Structural Survey with photographs or videos taken for future reference. Based on the findings of these surveys, a demolition plan shall then be prepared and submitted to the Buildings Department for approval. The demolition plan must also be accompanied by a report together with structural calculations assessing the stability of the building to be demolished and all affected buildings, structures, streets, land and services.

  • 2.1.1           Building Survey
  • Record Drawings

Prior to the Building Survey, the existing record plan, including layout plan showing adjoining properties, pedestrian walkway, roads and street, etc. shall be retrieved.

  • Survey Items

The Building Survey shall cover the following:

  • The construction materials;
    • The existing use and, if possible, the past uses of the building prior to demolition;
      • The presence of wastewater, hazardous materials, matters arising from toxic chemicals, flammable or explosive and radioactive materials, etc. and possible presence of materials which can contribute to air pollution and soil contamination;
      • Potential dangerous areas, e.g., abnormal layouts, presence of enclosed voids, and non-ventilated light wells which may trap obnoxious gas at the bottom;
      • Adjoining properties and site conditions, such as the existence of slope and retaining wall, wall supporting ground, illegal structures, bridges, underground railway and its above ground structures, including entrances, vent shafts, distribution substations, traction substations, plantrooms, overhead railway structures, surface track sections, overhead cables or guy wires, and other utility service connections;
  • Drainage conditions and possible problems on water pollution, flooding and erosion, especially on sloping sites and water receiving bodies;
    • Shared facilities with adjoining building, including common staircases, party walls, and possible effect on it, such as self-enclosed walls to the adjoining buildings, during demolition;
      • Hoarding and covered walkway requirements;
      • Adjoining pedestrian and vehicular traffic conditions;
      • Available headroom, clear spaces and distance of building from lot boundary which may affect the loading operation and transportation of building debris during demolition;
      • The sensitivity of neighbourhood with respect to noise, dust, vibration and traffic impact. For building/structures to be demolished, confirming whether it is within the scope of the designated projects specified in schedule 2 of the Environmental Impact Assessment Ordinance;
      • Available site area to allow on-site sorting of building debris; and
      • Street furniture such as fire hydrant, parking space/metres, street light, street sign and hawkers’ stalls which could be affected by the demolition project.
  • Hazardous Materials
  • Unless the Building Survey reviews that no obvious hazardous material is present in the building, the Authorized Person shall cause proper sampling and testing for the hazardous materials;
    • In the case when hazardous materials e.g., asbestos containing materials, or petroleum, are present, they shall be removed and cleaned/disposed of according to the statutory requirements administered by the Environmental Protection Department, Fire Services Department, Labour Department and any other Government Departments, referred to in Appendix D;
      • In the case when the site has previously been used to store chemicals, and other dangerous goods, soil contamination assessment shall be required at pre-demolition stage and/or post-demolition stage; and
  • In the case when the site has previously been used to store explosives, special procedures to ensure no explosives remain on site will be required.

Code of Practice for Demolition of Buildings – Definitions

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  1. Definitions

For the purpose of this Code, the following definitions shall apply:

“Authorized Person” means a person whose name is on the Authorized Persons’ register kept by the Building Authority under section 3(1) of the Buildings Ordinance :

  • as an architect; or
  • as an engineer; or
  • as a surveyor;

“Blasting Expert” means a person who is the holder of a valid mine blasting certificate or a special authorization issued by the Commissioner of Mines pursuant to Dangerous Goods (General) Regulations 47.

“Building Height” means the vertical distance measured from the top most part of the building to be demolished to the lowest ground level;

“Building Survey” means an inspection on the building and its surroundings aiming at spotting any potential problems that may arise during demolition and developing a method statement for demolition;

“Catch Platform” is a temporary structure erected on top of the covered walkway or underneath the structures that are being demolished including, but not limited to, balconies and cantilevered structures for the purpose of catching and retaining debris and to protect the area beneath such structures being demolished;

“Catchfan” is a temporary structure erected around and attached to or abutting the exterior wall of the building being demolished for the purpose of catching and retaining debris that fall outside the building;

“Covered Walkway” means a temporary structure with protective roof erected along the site boundary and on or adjacent to the existing footpath to protect pedestrians from the falling debris during demolition;

“Demolition” means dismantling, razing, destroying or wrecking any building or structure or any part thereof by pre-planned and controlled methods;

“Demolition Plan” is a plan prescribed by Building (Administration) Regulation 8(3) in respect of demolition works.

“Hanging Structure” is an unconventional structure that is supported from above by tension members such as suspended cables, tie rods or other means;

“Hanging Tie” means the tension members providing supports to a hanging structure.

“Hoarding” means a temporary fence enclosure erected along the site boundary to separate the demolition site from the adjacent properties;

“Implosion” means demolition with the use of explosives, in which, the building debris falls inwards or in a controlled manner;

“Implosion Expert” means a person who has acquired adequate knowledge and experience in building implosion through training and practical experience and is competent in taking up the full responsibility to design, organise and control building implosion, subject to approval by the Building Authority and the Commissioner of Mines.

“Non-Ventilated Light Well” means a light well which does not provide either natural ventilation through openings at both top and bottom, or mechanical ventilation that allow circulation of air;

“Party Wall” means a common wall that separates two adjoining buildings;

“Public Filling Area” means dumping site operated by the Government of the Hong Kong Special Administrative Region for receiving suitable construction and/or demolition waste for reclamation and land formation projects;

“Registered Specialist Contractor in the Demolition Category” means a person whose name is for the time being on the sub-register for the demolition category in the register of specialist contractors maintained under section 8A of the Buildings Ordinance;

“Registered Structural Engineer” means a person whose name is for the time being on the structural engineers’ register kept under section 3(3) of the Buildings Ordinance;

“Standards of Scaffold” means vertical members of scaffolding;

“Stability Report accompanying Demolition Plan” is a stability report which includes stability checking calculations for the building to be demolished, its supports, if any, the adjoining properties and the loading due to powered mechanical plants, or equipment, and its contents are stated in Building (Administration) Regulation 8(4).

“Structural Survey” means a survey on the existing structural element prior to demolition in order to check the layout arrangement of structural elements, the state of maintenance and deterioration, and any structural implication that may affect the demolition;

“Thermal Lance” means an intense heat process used to cut or sever structural elements, including reinforced concrete elements, by means of a high temperature torch with heat source generated from fusion of oxygen and metal.

Code of Practice for Demolition of Buildings – Scope

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  1. Scope

This Code of Practice outlines good practices for the planning and implementation of demolition works for different types of buildings in Hong Kong aiming at minimising the risks of :

  • causing damage to persons and properties of the public;
    • endangering the health and safety of site personnel; and
    • damaging the neighbourhood environment.

The Code is intended to give guidelines for engineering practice and safe procedures for various demolition methods and to provide guidance on the compliance with relevant requirements of the Buildings Ordinance and its subsidiary regulations. Aspects related to environmental, occupational safety and health should be referenced to other relevant ordinances and regulations.

This Code sets out the guidelines for demolition of buildings and is applicable to individual structures, partial demolition of buildings, basements, underground tanks, and common civil engineering structures, e.g., silos, industrial plants, piers, etc. However, this Code is not intended to cover unauthorized building works and major civil engineering works, such as underpinning, excavation, highway or railway bridges and dams. As for removal of unauthorized building works, reference should be made to the ‘Guidelines for the Removal of Typical Unauthorized Building Works and General Maintenance of External Walls’ issued by the Buildings Department.

This Code covers methods commonly used in building demolition. Any other demolition methods may also be used subject to careful consideration and recommendations made by the Authorized Person, Registered Structural Engineer and Registered Specialist Contractor in the Demolition Category (hereinafter referred to “Registered Specialist Contractor (Demolition)”), or their consultants based on well supported scientific research and engineering assessment.

Code of Practice for Demolition of Buildings – FOREWORD

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The Draft Code of Practice for Demolition of Buildings was first issued in February 1998 to provide guidance on safe and good practices for demolition works and for compliance with the requirements of the relevant provisions of the Building (Administration) Regulations and Building (Demolition works) Regulations relating to demolition works.

Throughout the years since its adoption, the Draft Code has been well received by the practitioners. Besides, they have been offering valuable comments on the use of the Draft Code based on their experience gained from its application. The Buildings Department   has considered and adopted their constructive views in the present review of the Draft Code which has thus been refined and adopted as this Code of Practice.

The Code contains basic information for the practitioners on better planning and control when carrying out demolition works. It also includes the latest development of the regulatory control on site supervision for demolishing complex structures. This Code should be read and used in conjunction with the Buildings Ordinance and the aforesaid Regulations when preparing demolition plans for approval by the Building Authority. Users of the Code should exercise their own professional judgement in the application of this Code in selecting the most suitable demolition method.