Buildings Department
2013.8.22 Buildings Department intends to apply for closure order in respect of 51 Kai Ming Street, August 22, 2013 2011.10.14 Report on the Collapse of the Canopy of a Building at 3 Kin Kwan Street, Tuen Mun - T.M.T.L. 87 on 9 June 2011
2011.10.07 Press release Canopy collapse due to lack of maintenance (with photo) - Thursday, October 6, 2011 2011.8.17 BD responds to Coroner's verdict - Tuesday, August 16, 2011
2011.6.10 Buildings Department organises territory-wide inspection of buildings with cantilevered slab canopies
2011.3.01 Findings of investigation into cause of building vibration at No.18-20 Tai Wong Street East
2010.4.26 Buildings Department report on building collapse in Ma Tau Wai Road and inspection results of buildings aged 50 or above (with photos/video)
2010.2.24 Buildings Department to demolish 45G and 45H Ma Tau Wai Road
2010.1.29 Report on the Collapse of the Building at 45J Ma Tau Wai Road, To Kwa Wan, Kowloon - K.I.L. 8627 on 29 January 2010
Developement Bureau - Studies and Reports1. Buildings Department's Review on Building Safety Enforcement Procedure and Practices :
Buildings Department's Review Report
Professor Ko Jan-ming's Independent Review on the Buildings Department's Report
Mr Daniel Lam's Independent Review on the Buildings Department's Report
Discussion Paper for the Legislative Council on the Independent Experts' and the Buildings Department's Reports
2. Review of Investigation Report on the Flooding in Sha Po Tsai Village, Tai Po on 22 July 2010
Investigation Report on the Flooding in Sha Po Tsai Village, Tai Po on 22 July 2010 - Executive Summary (Relevant Document uploaded in website of Drainage Services Department)
3. Response of the Development Bureau on a Residential Development next to Phase 8 of Mei Foo Sun Chuen (i.e. Remaining Portion of New Kowloon Marine Lot No. 25 (NKML 25 R.P.) and Section B of New Kowloon Marine Lot No. 25 (NKML 25 S.B))
Housing Department 1. The Report of the Investigation Panel on AccountabilityPiling Contract 166/1997 of Shatin Area 14B Phase 22. Select Committee on Building Problems of Public Housing Units
Architectural Services Department 1. Investigation Report on the Incident of Fallen Metal Gate on 5 May 2009 at Hang Ngai Manufacuring & Hostel 3 Hung Ling Street, Hung Hom, Kowloon
2012年6月14日 星期四
2009年6月30日 星期二
Workmanship and Common Defects in Hong Kong
(Summary of a book " Build with Heart & Care". The book is good for beginner)
Table of Content:
I. Basement
II. Building Facades
III. Podium and Roof
IV. Bathroom, Kitchen, Plumbing and Drainage
V. Tiling and Rendering Works
VI. Concrete Works
I. Basement
I. Basement
1.0 Major Concerns - Water/moisture ingress 1.1 Common Defects and possible causes: e.g. insufficient compaction of concrete, improper installation of waterproofing system, improper position of construction joints/movement joints and damage of waterproofing system
1.1.1 Water seepage through basement retaining walls : Water leakage and damp patches; 1.1.2 Water leakage from smoke vents: To prevent ingress, smoke vents should be designed as vertical in plane, i.e. dog-house. 1.1.3 Water Ingress to Lift Pits: Improvement e.g. external tanking and sump pit 1.2 Common methods (i) drained cavity wall (ii) waterproof basement walls and (iii) application of waterproofing membrane over and on outside surface of the basement wall/slab, e.g. Miradrain.
1.3 Rectification: Drip tray with PVC pipe to collect excess leaking water, chemical injection along cracks/joints and etc.
Practice references:
II. Building Facades
2.0 Major Concerns: Water intrusion, corrosion of reinforcement, debonding of plaster/render, peeling off of tiling/paint and deterioration of services equipment and fixtures.
2.1 Common defects
2.1.1 Water seepage through gaps/grouting around window: Structural opening is built too large and the gap filled with wrong materials.
2.1.2 Defective sealants/gaskets in window frames: Improperly flashed windows, applied sealant or window frame being deformed during handling/installation, poor sealant application e.g. improper cleaning of glass, inadequate application and incorrect thickness of sealant, and missing backer road in the joint etc.
2.1.3 Water seepage through curtain wall system: Poor workmanship or deterioration of sealant/gasket, blockage of weep holes, etc.
2.2.3 Water bar or small void, e.g. drip groove, should be provide underneath window frame to avoid capillary action seepage.
2.2.4 Hollow window frame section should be properly sealed up at the open ends.
2.2.5 The wall finishes should be lapped with the window frame and sealed with suitable weatherproof sealant.
Practice References:
Water seepage through gaps/external wall
III. Podium and Roof
3.0 Major Concerns: Water penetration, crack and deterioration of roofing system
3.1 Common defects
3.1.1 Failure at waterproofing system of roof: Water stain or damp patches under podium slab
3.1.2 Problem with expansion joints: Up-stand design and proper weatherproof sealant are critical for waterproofing at roof and podium
3.1.3 Water ponding on podium level: Insufficient fall to floor drain: Rainwater runoff is not directed to rainwater outlet pouints or outlets are blocked
3.1.4 Surface cracks of podium floor finishes/tiles: Excessiev drying shrinkage in substrate, overloaded traffic on podium or insufficient provision of expansion joints
3.1.5 Cracks on roof parapet wall: e.g. Cracks and debonding of surface finishes along base of parapet
3.1.6 Pipeworks constructed across the expansion joint
3.1.7 Expansion joint constructed improper location e.g. crub or staircase etc.
3.2 Recommendations
3.2.1 Up-stand design of expansion joint at roof
3.2.2 Provision of typical waterproofing details: e.g. Angle fillet and tuck-in
3.2.3 Infra-red thermographic survey was carried out after completion of waterproofing works and flooding test to ensure satisfactory works performance.
Practice References:
IV. Bathroom, Kitchen, Plumbing and Drainage
4.0 Major concerns: Water seepage through internal walls and floor slab, water ponding under bathtub, and water leakage from defective drainage and supply piles.
4.1 Common deffects
4.1.1 Water seepage through internal wall and floor slab: Caused by leakage from fitments, bathtubs, shower trays, concealed pipes or drains due to improper connection of joints, deterioration of piping materials, poor application of sealants or occurrence of cracks.
4.1.2 Water ponding under bathtub: Leaking water supply, poor conenctions or deterioration of piping, failure of sealant along bathtub
4.1.3 Water leakage from defective drainage and water supply pipes: e.g. Improperly sealed tile openings for water pipe outlets
4.1.4 Incomplete waterproofing application at bathroom walls
4.1.5 Poor grouting on tile joints in bathroom
4.2 Recommandation
4.2.1 Application of waterproofing mambrane with sufficient height: >2000m high for bathtub and shower tray; >1500mm high for kitchen and bathroom
4.2.2 Exposed design of water pipes
4.2.3 Water pressure test for water pipes: FOS 1.5
Practice references:
V. Tiling and Rendering Works
5.0 Major concerns: Cracking, debonding, leaching of external wall tiles/rendering, and debonding or bulging of internal wall tiles/plastering
5.1 Common defects
5.1.1 Debonding of external tile rendering: Poor preparation of parent substrate surface, spalling due to corrosion of reinforcement
5.1.2 Cracking on external wall rendering: Cracking caused by excessively thin/thick render (15-25mm in normal), expansion/movement of the substrate, moisture penetration, and sub-standard substrate preparation
5.1.3 Debonding of external wall tiles: Poor preparation of substrates, lack of bond between bedding materials/adhesives and tiles, insufficient provision of movement joints and cyclic severe weathering
5.1.4 Leaching on external wall tiles: Salts within concrete or masonry come out of the joint between tiles. It is process in which alkaline material (e.g. lime) become soluble and then migrate to the surface and dry. These material become carbondated from the atmosphere and become crystalline and form white deposit
5.1.5 Debonding of internal plastering and wall tiling: Inadequate preparation of substrate, over-rich mixes and very thick layers of plaster, insufficient provision of movement joints
5.1.6 Bulging of internal wall tiling: Differential movements, insufficient provision of movement joints, poor bonding or use of inferior adhesives
5.2 Recommendations:
5.2.1 Sufficient movement joint for tiles and rendering: The joint should be constructed full depth of rendering. BS5385 refers
5.2.2 Proper substrate preparation: Application of spatterdash to cover the substrate surface completely and form a rough texture with nodules. The substrate myst be cleaned by brushing or water jetting. Pre-wet may be necessary whlie the substrate is very adsorbent.
Adhesives should comply with BS EN12004:2001. Which adhesives is used, the whole back of tile should be in contact with the adhesive with no voids behind
5.2.3 Solution to prevent leaching: Some additives, efflorescence-reducing admixtures can help to reduce efflorescence.
Practice references:
Adhesive
VI. Concrete Works
6.0 Major concerns:
(i) poor fixing and placement of reinforcement, (ii) poor placing of concrete, (iii) poorly compacted concrete, (iv) inadequate curing of concrete, (v) incorrect mix proportions, (vi) poor formwork and (vii) improper cleaning and treatment between construction joints.
6.1 Common defects
6.1.1 Concrete spalling: Corrosion of reinforcement due to moisture/water ingress, chloride penetration, or carbonation
6.1.2 Cracking on carpark floor: Shrinkage and movement cracks which may be caused by overloading, movement induced by thermal/moistures changes, poor quality of site work, or insufficient curing of concrete
6.1.3 Insufficient concrete cover
6.1.4 Honeycomb and debris embedded in concrete: Insufficient vibration and poor attitude
6.1.5 Diagonal cracks in wall at corners of door and window opening: Common causes are due to moisture/thermal shrinkage of concrete, or insufficient trimming bars installed
6.2 Recommendation
6.2.1 Workability: Ability of freash concrete passing through congested reinforcement. Slump can be increased by adding chemical admixtures, such as water reducing agents, or PFA
6.2.2 Reinforcement congestion: Consideration of buildability in design, and sufficient compaction during concreting
6.2.3 Good quality of spacers and chairs: Reinforcement should be securely and accurately fixed in positions using approved spacers and chairs
6.2.4 Avoid excessive compaction induce segregation of concrete
Practice references:
Other internet information:
- BS8007 Code of practice for design of concrete structures for retaining aqueous liquids
- BS8102 Code of practice for protection of structures against water from the ground
- Guide to the design of waterproof basement (1978),CIRIA
- Water-resisting basement construction" a guide: safeguarding new and existing basements against water and dampness (1995), CIRIA
II. Building Facades
2.0 Major Concerns: Water intrusion, corrosion of reinforcement, debonding of plaster/render, peeling off of tiling/paint and deterioration of services equipment and fixtures.
2.1 Common defects
2.1.1 Water seepage through gaps/grouting around window: Structural opening is built too large and the gap filled with wrong materials.
2.1.2 Defective sealants/gaskets in window frames: Improperly flashed windows, applied sealant or window frame being deformed during handling/installation, poor sealant application e.g. improper cleaning of glass, inadequate application and incorrect thickness of sealant, and missing backer road in the joint etc.
2.1.3 Water seepage through curtain wall system: Poor workmanship or deterioration of sealant/gasket, blockage of weep holes, etc.
2.1.4 Cracking/debonding of finishes on external wall
2.1.5 Water seepage through external wall: Porous concrete, unplucked form tie holes and cracks in concrete wall
2.1.6 Water staining of dry-fixed stone cladding: Panels are not treated with waterproofing sealer or porous due to weathering effect
2.2 Recommendation
2.2.1 Window opening should be accurately constructed to avoid oversized opening.
2.2.2 The gap between window frame and wall opening should be filled in by non-shrink grout with waterproofing additive.2.2.3 Water bar or small void, e.g. drip groove, should be provide underneath window frame to avoid capillary action seepage.
2.2.4 Hollow window frame section should be properly sealed up at the open ends.
2.2.5 The wall finishes should be lapped with the window frame and sealed with suitable weatherproof sealant.
2.2.6 Windows with lintel and sill projection out from windows with ample outward fall.
Practice References:
Water seepage through gaps/external wall
- Building maintenance technology in tropical climates (1995), Singapore University Press
- Walls, windows and doors: performance, diagnosis, maintenance, repair and the avoidance of detects (1998), Harrison, W.H., Construction Research Communications Ltd.
- Good industry practices - Waterproofing for external wall (2004), Singapore: Building and Construction Authority
- Quality field practices (2001), Chapters 13, Hong Kong Housing Society
- BS EN 12365: Part I (2003), Building hardware, Gasket and weather-stripping for doors, windows, shutters and curtain walling
- Good industry practices - Aluminium windows (2004), Singapore: Building and Construction Authority
- Quality field practices (2001), Chapters 15, Hong Kong Housing Society
- Specification for aluminum alloy windows (2000), Singapore Productivity and Standards Board
- BS EN 13051, Curtain walling -Site test for watertightness (2001)
- BS EN 13830, Curtain walling -Product standard (2003)
- BS EN 13119, Curtain walling -Terminology (2007)
- Cladding fixings: good practice guidance (2000), CIRIA
III. Podium and Roof
3.0 Major Concerns: Water penetration, crack and deterioration of roofing system
3.1 Common defects
3.1.1 Failure at waterproofing system of roof: Water stain or damp patches under podium slab
3.1.2 Problem with expansion joints: Up-stand design and proper weatherproof sealant are critical for waterproofing at roof and podium
3.1.3 Water ponding on podium level: Insufficient fall to floor drain: Rainwater runoff is not directed to rainwater outlet pouints or outlets are blocked
3.1.4 Surface cracks of podium floor finishes/tiles: Excessiev drying shrinkage in substrate, overloaded traffic on podium or insufficient provision of expansion joints
3.1.5 Cracks on roof parapet wall: e.g. Cracks and debonding of surface finishes along base of parapet
3.1.6 Pipeworks constructed across the expansion joint
3.1.7 Expansion joint constructed improper location e.g. crub or staircase etc.
3.2 Recommendations
3.2.1 Up-stand design of expansion joint at roof
3.2.2 Provision of typical waterproofing details: e.g. Angle fillet and tuck-in
3.2.3 Infra-red thermographic survey was carried out after completion of waterproofing works and flooding test to ensure satisfactory works performance.
Practice References:
- BS8400: Part4 (1989) Workmanship on building sites - Code of practice for waterproofing
- Roofing failures (2003), Cash, C.G., SPON
- Flat roofing: design & good practice (1993), CIRIA
- Roofs and roofing: performance, diagnosis, maintenance, repair and the avoidance of defects (2000), Harrison, W.H.
IV. Bathroom, Kitchen, Plumbing and Drainage
4.0 Major concerns: Water seepage through internal walls and floor slab, water ponding under bathtub, and water leakage from defective drainage and supply piles.
4.1 Common deffects
4.1.1 Water seepage through internal wall and floor slab: Caused by leakage from fitments, bathtubs, shower trays, concealed pipes or drains due to improper connection of joints, deterioration of piping materials, poor application of sealants or occurrence of cracks.
4.1.2 Water ponding under bathtub: Leaking water supply, poor conenctions or deterioration of piping, failure of sealant along bathtub
4.1.3 Water leakage from defective drainage and water supply pipes: e.g. Improperly sealed tile openings for water pipe outlets
4.1.4 Incomplete waterproofing application at bathroom walls
4.1.5 Poor grouting on tile joints in bathroom
4.2 Recommandation
4.2.1 Application of waterproofing mambrane with sufficient height: >2000m high for bathtub and shower tray; >1500mm high for kitchen and bathroom
4.2.2 Exposed design of water pipes
4.2.3 Water pressure test for water pipes: FOS 1.5
Practice references:
- Good industry practices - Waterproofing for internal wet areas (2003), Singapore: Building and Construction Authority
- Quality field practices (2001), Hong Kong Housing Society
- Health aspects of plumbing (2006), WTO
V. Tiling and Rendering Works
5.0 Major concerns: Cracking, debonding, leaching of external wall tiles/rendering, and debonding or bulging of internal wall tiles/plastering
5.1 Common defects
5.1.1 Debonding of external tile rendering: Poor preparation of parent substrate surface, spalling due to corrosion of reinforcement
5.1.2 Cracking on external wall rendering: Cracking caused by excessively thin/thick render (15-25mm in normal), expansion/movement of the substrate, moisture penetration, and sub-standard substrate preparation
5.1.3 Debonding of external wall tiles: Poor preparation of substrates, lack of bond between bedding materials/adhesives and tiles, insufficient provision of movement joints and cyclic severe weathering
5.1.4 Leaching on external wall tiles: Salts within concrete or masonry come out of the joint between tiles. It is process in which alkaline material (e.g. lime) become soluble and then migrate to the surface and dry. These material become carbondated from the atmosphere and become crystalline and form white deposit
5.1.5 Debonding of internal plastering and wall tiling: Inadequate preparation of substrate, over-rich mixes and very thick layers of plaster, insufficient provision of movement joints
5.1.6 Bulging of internal wall tiling: Differential movements, insufficient provision of movement joints, poor bonding or use of inferior adhesives
5.2 Recommendations:
5.2.1 Sufficient movement joint for tiles and rendering: The joint should be constructed full depth of rendering. BS5385 refers
5.2.2 Proper substrate preparation: Application of spatterdash to cover the substrate surface completely and form a rough texture with nodules. The substrate myst be cleaned by brushing or water jetting. Pre-wet may be necessary whlie the substrate is very adsorbent.
Adhesives should comply with BS EN12004:2001. Which adhesives is used, the whole back of tile should be in contact with the adhesive with no voids behind
5.2.3 Solution to prevent leaching: Some additives, efflorescence-reducing admixtures can help to reduce efflorescence.
Practice references:
Adhesive
- BS5980 (1980), Specification for adhesive for use with ceramic tiles and mosaics
- BS EN1348 (1999), Adhesives for tiles - Determination of tensile adhesion strength for cementitious adhesives
- BS EN12004 (2001), Adhesives for tiles - Definitions and specifications
- BS EN13914 part 1 (2005), Design, preparation and application of external rendering and internal plastering - External rendering
- BS8000 Part 11.1 (1989), Workmanship on building sites, Code of practice for wall and floor tiling - Ceramic tiles, terrazzo tiles and mosaics
- BS 5385 Part 1 (1995), Code of practice for wall and floor tiling - Design and installation of internal ceramic and natural stone wall tiling and mosaics in normal conditions
- BS 5385 Part 2 (2006), Code of practice for wall and floor tiling - Design and installation of internal ceramic and mosaic wall tiling in normal conditions
- Good industry practices - Ceramic tiling (2003), Building and Construction Authority, Singapore
- Good industry practices - Marble and granite finishes (2003), Building and Construction Authority, Singapore
- Professional tiling: how to install, repair or replace ceramic tile (1993), Field E.M. & Field S.G.
- Quality field practices (2001) Chapters 12 & 14, Hong Kong Housing Society
VI. Concrete Works
6.0 Major concerns:
(i) poor fixing and placement of reinforcement, (ii) poor placing of concrete, (iii) poorly compacted concrete, (iv) inadequate curing of concrete, (v) incorrect mix proportions, (vi) poor formwork and (vii) improper cleaning and treatment between construction joints.
6.1 Common defects
6.1.1 Concrete spalling: Corrosion of reinforcement due to moisture/water ingress, chloride penetration, or carbonation
6.1.2 Cracking on carpark floor: Shrinkage and movement cracks which may be caused by overloading, movement induced by thermal/moistures changes, poor quality of site work, or insufficient curing of concrete
6.1.3 Insufficient concrete cover
6.1.4 Honeycomb and debris embedded in concrete: Insufficient vibration and poor attitude
6.1.5 Diagonal cracks in wall at corners of door and window opening: Common causes are due to moisture/thermal shrinkage of concrete, or insufficient trimming bars installed
6.2 Recommendation
6.2.1 Workability: Ability of freash concrete passing through congested reinforcement. Slump can be increased by adding chemical admixtures, such as water reducing agents, or PFA
6.2.2 Reinforcement congestion: Consideration of buildability in design, and sufficient compaction during concreting
6.2.3 Good quality of spacers and chairs: Reinforcement should be securely and accurately fixed in positions using approved spacers and chairs
6.2.4 Avoid excessive compaction induce segregation of concrete
Practice references:
- BS8000:Part 2 (1990) Workmanship on building sites - Code of practice for concrete work - Sitework with in situ and precast concrete
- BS8000Part 2.1 (1990) Workmanship on building sites - Code of practice for concrete work - Mixing and transporting concrete
- Concrete materials: problems and solution (1997), Levitt, M., E & FN Spon
Other internet information:
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