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ARCHITECTURAL SERVICES DEPARTMENT
GENERAL SPECIFICATION FOR BUILDING (1993)
CORRIGENDUM NO. GS9304
(June, 1999)
[ having incorporated corrigendum No.1 , 2 & 3 (Annex 1, 2 & 3)
issued in 1994, 1995 & 1997]
SECTION 1
PRELIMINARIES
Add to Clause
1.02
BSEN European Standard
ISO International Standard
SECTION 2
DEMOLITION, SITE CLEARANCE & ALTERATIONS
(existing) Clause
2.01
Comply with the Building (Demolition works) Regulations Regulations
replace with Comply with all relevant legislation, Codes of Practice and
Practice Notes in connection with demolition works. Particular
attention is drawn to the following :-
Regulations,
Ordinances,
Codes of
Practice &
Practice Notes
(i) Building (Demolition Works) Regulations (Demolition)
(ii) Construction Sites (Safety) Regulations
(iii) Noise Control Ordinance(iv) Air Pollution Control (amendment) Ordinance
(v) Building Planning Regulations
(vi) The Factories and Industrial Undertakings Ordinance
(vii) The Factories and Industrial Undertakings (Lifting
Appliances and Lifting Gear) Regulations
(viii) The Factories and Industrial Undertakings (Noise at
Work) Regulations
(ix) The Factories and Industrial Undertakings (Safety
Officers and Safety Supervisors) Regulations
(x) Air Pollution Control (Construction Dust) Regulations
(xi) The British Standard Code of Practice for Demolition :
BS 6187.
(xii) Building Department Practice Notes Nos. 71 & 75 for
Authorised Persons and Registered Structural
Engineers
(xiii) Building .Department Practice Notes Nos. 4 , 6 & 26
for Registered Contractors
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(existing) Clause
2.03
Report to the SO details of any suspended asbestos containing
materials found during the survey. If required by the SO,
arrange for an Approved Laboratory to take bulk sample for
analysis to determine the content and the type of asbestos.
Asbestos
materials
replace with Before any demolition or alteration work commences, a
registered asbestos consultant shall be appointed to conduct a
thorough investigation of the building for the presence ofasbestos containing material at the premises and submit an
Asbestos Investigation Report and, if asbestos containing
material is found, an Asbestos Abatement Plan to the
Environmental Protection Department at least 28 days before
the asbestos abatement work commences.
Asbestos
materials
When appropriate, a registered asbestos laboratory shall be
appointed to carry out sampling, measurement or analysis of any
suspected asbestos containing material.
Asbestos removal work shall be carried out by a registeredasbestos contractor under the supervision of a registered
asbestos consultant in compliance with relevant legislation and
codes of practice.
If during the course of the general demolition work, hidden
suspected asbestos containing material is found, stop work
immediately and report to the SO.
(existing) Clause
2.04
Submit a statement as to the proposed method and sequence of
demolition if required by the SO. The SO reserves the right to
prohibit any method of execution of the Works which he regardsas unsafe.
Method of
execution
replace with Before commencement of work, submit a method statement to
the SO as to the proposed method and sequence of demolition
of the building and a safety plan which shall cover the risk
assessment and safety measures for such method statement.
The SO reserves the right to prohibit any method of execution
of the Works which he regards as unsafe.
Method of
execution and
safety plan
The method statement shall be prepared in accordance with the
requirements of the Building Department Practice Notes Nos.71 and 75.
Prior to commencement, the method statement including a
demolition plan and demolition sequence written in both
English and Chinese shall be posted in the site office and on
each operation level. The documents shall fully explain the
requirements to site supervisors, operators and workers.
A Competent Person as stated in Clause 8 of the Building
Regulations (Demolition Works) shall have a minimum of 3
years of relevantexperience and shall be specifically appointed
by the Contractor for the direct supervision of demolition works.
Under the safety plan, a part time registered safety officer and a
full time safety supervisor are to be provided. Safety training
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shall be provided to all site supervisors by the contractor.
Drawing information, particularly for unconventional layouts
and special structures, will be made available to the contractor if
possible. The contractor shall state in his method statement if it
is based on such drawings. In the absence of drawings, the SO
may require a detailed structural survey to be carried out and
endorsed by a Registered Structural Engineer (or equivalent) todefine the existing structure and the appropriate method and
sequence of demolition.
No work on site shall be allowed to commence until the
proposed method statement has been accepted and all
precautionary measures, hoardings, covered walkways, and
other requirements are in place.
The contractor shall obtain all necessary permits from the
Highways and Transport Departments.
(existing) Clause
2.28
Cause as little inconvenience as possible to tenants, occupants
or adjoining owners and the public. prevent duct arising by
well watering debris during the works.
Avoidance of
nuisances
replace with Cause as little inconvenience as possible to tenants, occupants,
adjoining owners and the public. Prevent dust arising by
approved dust control methods.
Avoidance of
nuisances
(existing) Clause
2.30
The removal of asbestos containing materials shall be carried
out by an approved specialist contractor.
Asbestos
removal
replace with The removal of asbestos containing materials shall be carried
out by an approved registered asbestos contractor prior to
commencement of general demolition works to avoid
contamination of debris arising from the demolitions.
Asbestos
removal
(existing) Clause
2.42
Comply with all relevant current legislation, Codes of Practice
and guidance notes in connection with asbestos removal works.
Particular attention shall be drawn to the following :-
Legislation,
Codes of
Practice and
Guidance
Notes
(i) Factories and Industrial Undertakings (Asbestos)Special Regulation 1986.
(ii) Factories and Industrial Undertakings (Asbestos)
(Approval of Respiratory Protective Equipment)
Notice.
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(iii) Control of Asbestos at Work - code of Practice
issued by Labour Department.
(iv) Code of Practice on Handling, Transport and
Disposal of Asbestos Wastes issued by
Environmental Protection Department.
(v) Air Pollution Control Ordinance.
(vi) The Protection of Working Health Series - Asbestos
(Issued by Labour Department).(vii) Guide to the Factories and Industrial Undertaking
(Asbestos) Special Regulations.
replace with Comply with all relevant legislation and Codes of Practice
in connection with asbestos removal works. Particular
attention shall be drawn to the following :-
Regulations,
Ordinances
and Codes of
Practice
(Asbestos)
(i) Factories and Industrial Undertakings (Asbestos)
Regulations.
(ii) Air Pollution Control Ordinance.
(iii) Air Pollution Control (Amendment) Ordinance.
(iv) Air Pollution Control (Asbestos) (Administration)
Regulations
(v) Factories and Industrial Undertakings (Asbestos)
(Approval of Respiratory Protective Equipment)
Notice.
(vi) Code of Practice on Handling, Transportation and
Disposal of Asbestos Waste, Environmental
Protection Department, 1993.
(vii) Code of Practice on Asbestos Work using FullContainment or Mini containment methods,
Environmental Protection Department, Hong Kong.
(viii) Code of Practice on Safe Handling of Low Risk
Asbestos-Containing Material, Environmental
Protection Department, Hong Kong.
(ix) Code of Practice on Safe Handling of In-situ
Asbestos-Containing Material, Environmental
Protection Department, Hong Kong.
(x) Code of Practice on Asbestos Work using Glove
Bag Method, Environmental Protection Department,
Hong Kong.
SECTION 3
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EXCAVATION AND EARTHWORK
add Clause
3.01 (ii)
The method of testing of the total sulphate content shall be in
accordance with BS 1377 (as modified in accordance with
GEO Report No. 36 entitled "Methods of Test for Soils in Hong
Kong for Civil Engineering Purposes (Phase 1 Tests). Test
3.5.5.
(existing) Clause
3.01
(viii)
"Special filling material" is to be "general filling material"
capable of passing through a 75mm BS sieve. The material is to
have the following characteristics:
replace with Special filling material is to be general filling material
capable of passing through a 75mm BS sieve. The material
shall be sampled and tested according to BS 1377 (as modified
in accordance with GEO Report No. 36, entitled Methods of
Test for Soils in Hong Kong for Civil Engineering Purposes
(Phase 1 Tests). The material is to have the following
characteristics :
(existing) Clause
3.01
(viii)(a)
Liquid limit is not to exceed 45%. Sample and test to be toBS
1377.
replace with Liquid limit is not to exceed 45%. Sample and test to be to
GEO Report No. 36 Test 2.4.3.
(existing) Clause
3.01
(viii)(b)
Plasticity index is not to exceed 20%. Sample and test to be to
BS 1377.
replace with Plasticity index is not to exceed 20%. Sample and test to be toGEO Report No. 36. Test 2.5.3
(existing) Clause
3.21 (ii)
Determine the maximum dry density and optimum moisture
content in accordance with BS 1377 Test No. 12 or 13 as
directed by the SO. Test each soil type when first used and
thereafter at the same time as every set of field density tests is
carried out or whenever the SO may direct. Unless otherwise
specified, the number of tests required shall be as stated in
Table 3.3. Keep records identifying the soil type and location
in the Works and showing the following information for each
series of tests :
(a) Maximum dry density.
(b) Optimum moisture content.
replace with Determine the maximum dry density and optimum moisture
content in accordance with GEO Report No. 36 "Methods of
Test for Soil in Hong Kong for Civil Engineering Purpose
(Phase 1 Tests)" as follows :-Optimum Moisture Content: GEO Report No. 36 test 4.3.3A, 4.3.3B,
4.3.4A or 4.3.4B whichever is
instructed by the SO.Maximum dry density: GEO Report No. 36 test 4.3.3A, 4.3.3B,
4.3.4A or 4.3.4B whichever as instructed by
the SO.
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Test each soil type when first used and thereafter at the same
time as every set of field density tests is carried out or whenever
the SO may direct. Unless otherwise specified, the number of
tests required shall be as stated in Table 3.3. Keep the records
identifying the soil type and the location within the works.
(existing) Clause
3.21(iii)
Determine the insitu field density and moisture content in
accordance with BS 1377 Test No. 15A or 15B (the sandreplacement method) as directed by the SO to determine the
relative compaction achieved.
replace with Determine the insitu field density and moisture content in
accordance with G.E.O. Report No. 36, test 9.2.1 or 9.2.2 as
directed by the SO to determine the relative compaction
achieved.
(existing) Clause
3.21
(iv)
Determine moisture content in connection with BS compaction
tests by means of a drying-oven. To expedite results, moisture
contents for field density tests may be determined by use of a"Speedy" moisture tester which, however, shall not be used
until it has been calibrated against moisture content tests
carried out in a drying-oven. Submit a calibration chart for
approval before the "Speedy" moisture tester is used.
replace with Determine moisture content in accordance with compaction
tests under GEO Report No. 36 by means of a drying oven. To
expedite results, moisture contents for field density tests may
be determined by use of a "Speedy" moisture tester which,
however, shall not be used until it has been calibrated against
moisture content tests carried out in a drying oven. Submit acalibration chart for approval before the "Speedy" moisture
tester is used.
SECTION 5
PILING WORK
(existing) Clause
5.04 (i)
The theoretical safe ...... exceed 25% of ...... Loading
capacity of
piles
replace with The theoretical safe ...... exceed 25% (20% only for precast
concrete piles) of......
Loading
capacity of
piles
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(existing) Clause
5.04
(iii)
Minimum yield stress with thickness
Steel Specification
Up to and
including
16 mm
Over 16 mm
Up to and
including 40 mm
BS 4360-Grade 43A 275 MPa 265 MPa
BS 4360
-Grade 50B 355 MPa 345 MPa
replace with Clause
5.04
(iii)
Minimum yield stress with thickness
Steel Specification
Up to and
including
16 mm
Over 16 mm
Up to and
including 25mm
Over 25 mm
Up to and
including 40 mm
BS 4360
-Grade 43A 275 MPa 265 MPa 265 MPa
BS 4360
-Grade 50B 355 MPa 345 MPa 345 MPa
BS 4360
-Grade 55C 450 MPa 430 MPa 415 MPa
add Clause
5.08
(vi)
The centres of all driven piles and of all piles deriving their
resistance mainly from friction shall be placed not less than
half the length of the perimeter of the pile or 500 mm,
whichever is the greater, from the site boundary.
(existing) Clause
5.12
Check the energy ......
W = Weight of the ram of the diesel hammer in KN.
Energy output
of diesel
hammers
replace with The use of diesel hammers for percussive piling shall be
prohibited.
Use of diesel
hammer
(existing) Clause5.14
(iii)
If the Hiley .......7.5 mm when hardwood packings at the pilehead and in the dolly are 100 mm thick.
replace with If the Hiley formula is used to calculate the loading capacity of a
pile, the temporary compression of the driving cap (Cc) shall be
taken as not less than 7.5 mm when the total thickness of
hardwood packings at the pile head and in the dolly is 100 mm
or less (refer to clause 5.18 for percussion steel H pile).
(existing) Clause
5.16
(iv)
Do not use a hammer of weight less than 70% of the
weight.....not less than 7.5mm.
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replace with Do not use a hammer of weight less than 50% of the weight of
the pile during the final set, and if a drop hammer is adopted
limit its stroke to not more than 1.2 m. For set calculation in
accordance with Clause 5.14 (iii), the temporary compression of
driving cap thereof (Cc) shall be taken as not less than7.5mm.
If specified, carry out Dynamic Pile Testing or use other
approved means to demonstrate at construction stage that the
maximum tensile stress solely arising from pile driving does notexceed 12 MPa.
(existing) Clause
5.16 (v)
(d)
Supply sample piles ...... Public Works Laboratory for testing
......
replace with Supply sample piles ...... Public Works Laboratory (unless
ordered otherwise by the SO for projects in rural areas) for
testing ......
(existing) Clause
5.18 (i)
Steel sections must comply with the requirement ofBS 4360
Grade 43A or 50B.
Percussion
steel H piles
replace with Steel sections must comply with the requirement ofBS 4360 Grade
43A, 50B or 55C.
Percussion
steel H piles
(existing) Clause
5.18
(iii)
Carry out splicing ...... shall be tested at a rate of one per hundred
joints or part thereof by ultrasonic ......
replace with Carry out splicing ...... shall be testedat a minimum rate of 1%
of the joints for piles of grade 43A, 50B steel and 10% of the
joints for piles of grade 55C steel by ultrasonic ......
(existing) Clause
5.18
only item (i) to (v)
add (vi) Provide one test specimen for every one hundred segments or
part thereof of each section of same thickness from the same
cast. For the purpose of this clause, same thickness means
similar sections with a variation in thickness not exceeding
+ 5 mm, and segment means every length of pile as rolled.
Test specimen shall be taken from sections selected at random
on site by the SO.
Prepare the test specimens to BS18 as directed and
appropriately mark and deliver them to a P.W. Laboratory, as
directed by the SO.
add (vii) Pile of same size but of different grades shall not be used in the
same site.
add (viii) If Hiley Formula is used to calculate the loading capacity of
percussion steel H pile, the temporary compression of the
driving cap(Cc) shall be taken as not less than 5 mm when the
total thickness of hardwood packings at the pile head and in the
dolly is 50 mm or less.
(existing) Clause Carry out site borings ......(54 mm diameter) ......
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5.19 (ii)
replace with Carry out site borings ......(61 mm diameter) ......
(existing) Clause
5.19
(iv)
Sound bedrock is defined as rock mass of at least 5 m thick and
being:
(a) Partially Weathered Rock (PW), having rock content
greater than 90% (PW 90/100) and with Rock QualityDesignation (RQD) greater than 40%; or
(b) Unweathered Rock (UW).
The rock description ....... published by GIS Hong Kong.
replace with Sound bedrock is defined as rock mass of at least 5 m thick and
being Grade III or better rock (as defined in GEOGUIDE 3,
Guide to Rock and Soil Descriptions prepared by
Geotechnical Engineering Office and published by GIS, Hong
Kong) with core recovery greater than 90%.
For design purposes, the average bearing pressure of piles on
sound bedrock shall not exceed the followings:
(a) 3 MPa for Grade III or better rock with core recovery
greater than 90%
(b) 5 MPa for Grade III/II or better rock with core recovery
greater than 90%
(c) 7.5 MPa for Grade II/I or better rock with core recovery
greater than 95%
(existing) Clause
5.19
(v)
The average bearing pressure of piles on sound bedrock shall
not exceed 5 MPa unless otherwise specified.
replace with The average bearing pressure of piles on sound bedrock shall
not exceed 3 MPa unless otherwise specified.
(existing) Clause
5.19
(vi)
When specified, the bearing pressure may be increase up to 7.5
MPa. The sound bedrock in this case shall be of a higher
quality with at least 5 m thick of UW with RQD equal to orgreater than 75%. Notwithstanding item (ii) above, carry out
site borings at all pile locations to determine the founding level
of each individual pile.
replace with When specified, the bearing pressure of piles on sound bedrock
may be increased to a maximum value of 7.5 MPa.
(existing) Clause
5.20
Non-percussion cast in-situ concrete piles are those not
exceeding 600mm diameter formed by boring. The
requirements of Clause 5.17 (i) and (ii) shall apply. Provide
reinforcement as specified.
Non-
percussion
cast in-situ
concrete piles
replace with (i) Non-percussion cast in-situ concrete piles are those not
exceeding 600mm diameter formed by boring. The
Non-
percussion
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requirements of Clause 5.17 (i) and (ii) shall apply. Provide
reinforcement as specified.
(ii) Before the commencement of piling works, install drill holes
whenever necessary, to obtain sufficient information for the
calculations of pile lengths. The position and number of the
drill holes should be agreed with the SO on site. Two copies
of the drill hole logs have to be submitted to the SO.
cast in-situ
concrete piles
(existing) Clause
5.21(v)
Do not use caissons with enlarged base unless otherwise
specified.
replace with The minimum clear working space inside the caisson (i.e.
excluding the lining) shall not be less than 1.8m diameter. Do
not use caissons with enlarged base unless otherwise specified.
(existing) Clause
5.21(vi)
No person shall enter ...... the following:
(a) Caisson shafts : Provide around each shaft suitable
toe boards of 150 mm minimum height and fencing orother barriers not less than 750 mm high to prevent ....
(b) Ventilation of shaft : Provide sufficient .... The
equipment shall be capable of supplying air at a rate
of not less than 25 litres per second. Provide, in
addition....
replace with No person shall enter......the following:
(a) Caisson shafts : Provide around each shaft suitable
toe boards of 200 mm minimum height and fencing
or other barriers to a height of between 900mm and
1150mm to prevent......(b) Ventilation of shaft : Provide sufficient....The
equipment shall be capable of supplying air at a rate
of not less than 25 litres per second per person.
Provide, in addition....
(existing) Clause
5.21(vi)
....(i) Regulations and Code of Practice : Ensure that proper
attention is paid to the appropriate sections of the Hong
Kong Construction Sites (Safety) Regulations, and also to
the Code of Practice for Safety Precautions in theConstruction of .....
replace with ....
(i) Regulations and Code of Practice : Ensure that proper
attention is paid to the appropriate sections of the Hong
Kong Construction Sites (Safety) Regulations, the Code
of Safe Working Practices for Hand-Dug Caissons
published by the Occupation Safety Health Council and also
to the Code of Practice for Safety Precautions in the
Construction of .....
(existing) Clause
5.22 (ii)
Construct piles to the .........to the specified designated position:
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(a) Percussion precast concrete pile )
Percussion precast prestressed tubular )
concrete piles )
Percussion cast in-situ concrete piles )
Percussion steel H piles ) 50mm
Non-percussion cast in-situ concrete Piles )
(b) Large diameter bored piles )Hand-dug caissons ) 75mm
replace with Construct piles to the .........to the specified designated position:
Percussion precast concrete pile )
Percussion precast prestressed tubular )
concrete piles )
Percussion cast in-situ concrete piles ) 75mm
Percussion steel H piles )
Non-percussion cast in-situ concrete piles )
Large diameter bored piles )Hand-dug caissons )
(existing) Clause
5.26 (i)
Backfill pits after ......BS 1377Test No. 12 or 13 as directed by
the SO. Determine the in-situ field density in accordance with
BS 1377Test 15A or 15B as directed by the SO.
Backfilling
replace with Backfill pits after ...... GEO Report No. 36 test no. 4.3.3B or
4.3.4B as directed by the SO. Determine the in-situ field density
in accordance with GEO Report No. 36 Test No. 9.2.1 or 9.2.2
as directed by the SO.
Backfilling
(existing) Clause
5.29
(iv)
Should the estimated ...... in accordance withBS 6089.
replace with Should the estimated ...... in accordance withCS1.
(existing) Clause
5.41(iv)
CAPWAP analysis
When specified, a number of piles under Dynamic Pile Testing
shall be subject to supplementary, rigorous laboratory wave
analysis using the CAPWAP (Case Pile Wave equation Analysis
Programme) or equivalent approved computer programme.
replace with The number of piles under Dynamic Pile Testing shall be as in
the table in Annex F and subject to supplementary, rigorous
laboratory wave analysis using the CAPWAP (Case Pile Wave
equation Analysis Programme) or equivalent approved
computer programme.
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(existing) Annex
F
Type
of pile
Steel H-piles,
Percussive Precast
Concrete Piles
Cast-insitu Concrete
Piles
Tests
Hand-
dug
Caissons
Large
Diameter
Bored Piles
& Barrettes 100
piles
* L/D30
VibrationTest - - - - 10% -
Dynamic
Pile Test
- - - 8% - -
Sonic
Coring
- All piles - - - -
*L = length of pile
D = diameter of pile
replace with Annex
F
Type of
pile
Steel H-piles,
Percussive Precast
Concrete Piles,
Precast PrestressedTubular Concrete
Piles
Cast-insitu Concrete
Piles
Tests
Hand-dug
Caissons
Large
Diameter
Bored
Piles &
Barrettes
100
piles
*
L/D30
Vibration
Test
- - - - 10% -
Dynamic
Pile Test
- - - 8%** - -
Sonic
Coring
- All piles - - - -
*L = length of pile
D = diameter of pile
**7% to be tested under CASE method and 1% to be tested for CAPWAP method
SECTION 6
STRUCTURAL CONCRETE WORK
(existing) 6.01 to 6.13
replace with GeneralClause
6.01 (i)
Falsework is defined as any temporary structure used to support
a permanent structure during erection until the permanent
structure is self-supporting.
Generally
(ii) Traditional formwork is assembled from individual elements
comprising of sheathing material referred in BS5975 and the
backing structure which supports the sheathing.
(iii) Formwork or forms is that section of the temporary works used
to give the required shape, surface finish and support to pouredconcrete. It consists primarily of sheathing material in direct
contact with the concrete and joists or stringers supporting the
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sheathing.
(iv) Permanent formwork or formwork left-in is formwork designed
to remain in position as part of the permanent work.
(v) Notwithstanding any other clause in the GS, the contractor shall
take sole responsibility for the safe transportation, assembly,
erection, maintenance and removal of formwork and falsework.
Design requirementsClause
6.02 (i)
Prior to construction, submit for approval the design,
supporting calculations, working drawings and working
procedures of formwork and falsework in accordance with BS
5975.
Design
submissions
(ii) When specified, submit the design of falsework (including
supports and foundations) and provide certification by an
independent engineer, at various stages, for the adequacy of the
design as well as its proper execution.
Clause
6.03
Design and construct formwork and falsework to withstand the
worst combination of the following without causing bulging or
deflection :
Loadings for
design and
construction
(i) Total weight of formwork, reinforcement and wet concrete.
(ii) Construction loads, including dynamic effects of placing,
compacting and construction traffic.
(iii) Wind loads.
MaterialsClause
6.04 (i)
Props shall be to BS 4074. No timber props and bracings shall
be permitted.
Props &
bracings
(ii) Formwork shall be timber or moulds of other materials against
which the concrete is cast.
Formwork
(iii) Formwork shall not be splitted, or have other defects such as
cracks.
(iv) Formwork ties shall be of a removable type. Formwork
ties
(v) In waterproof concrete any tie through the concrete shall be of a
type with a baffle and shall leave no holes in the concrete.
(vi) Surface retarders shall be of a type which shall not stain or
colour the concrete.
Surface
retarders
(vii) Release agents used on formwork for structures containing
potable water shall be non-toxic and shall not impart a taste to
the water.
release agent
(viii) Release agents containing mineral oil shall not be used. These
include barrier paint, polyurethane varnish, or wax.
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(ix) Release agent used on steel formwork shall contain a rust-
inhibiting agent.
(x) Polystyrene shall not be used as void formers and box-out
material unless permitted by SO.
Void formers
(xi) Wood preservatives in permanent timber formwork shall be to
clause 21.30.
Wood
preservatives
StorageClause
6.05 (i)
Store formwork off the ground on level supports and in a
manner which shall not result in damage or in deformation or in
contamination of the formwork.
Storage of
formwork
(ii) Release agents and surface retarders in sealed containers shall
be properly marked to identify the contents. They shall be
protected from exposure to conditions which may affect the
material. Store materials in accordance with the manufacturers
recommendations and do not use the materials after the
recommended shelf life has expired.
Storage of
release agents
and surface
retarders
Approval Procedures
Clause
6.06 (i)
Prior approval of the SO must be obtained before work proceeds
for casting concrete below ground against sides of excavation.
Work below
ground
(ii) Prior approval from the SO must be obtained before work
proceeds, for size, type and position of any holes, inserts or
fixings by the contractor or his sub-contractor. No part of the
concrete shall be drilled or cut without prior approval of the SO.
Holes, inserts
or fixings
(iii) Prior approval from the SO must be obtained before application
for the use, type and location of surface retarders and release
agents.
Surface
retarders and
release agents(iv) No reinforcement shall be fixed until the formwork has been
inspected and approved by the SO.
Inspection of
formwork
prior to fixing
of
reinforcement
Construction
Clause
6.07 (i)
Scaffolding shall not be used to support formwork or
falsework even under the erection or dismantling process.
Generally
(ii) Cambers shown on drawings relate to the concrete
immediately before the formwork is struck.
Cambers
Clause
6.08 (i)
Falsework shall be carried down to construction which is
sufficiently strong to afford the necessary support without
damage to any portion of the structure. Falsework
supported directly on soil shall not be permitted. Where
necessary, falsework shall be carried down to foundations
or other suitable bases.
Falsework
(ii) Falsework shall be arranged so that it can be readily
dismantled and removed from the cast concrete without
difficulty or damage to the permanent structure. Where
necessary, falsework shall be arranged so that the soffit
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can be retained in position for such period as required by
Clause 6.12/Table 6.1 of the general specifications.
Clause
6.09 (i)
Props shall be of sufficient strength and number and
placed in such a manner that they, adequately and without
excessive deflection, support the loads likely to be
imposed on them.
Props
(ii) Props shall be spaced at no more than 2 m centres in bothdirections and shall be adequately cross-braced.
Clause
6.10(i)
Formwork shall be firmly supported and individual
panels shall be of a rigid nature.
Formwork
(ii) Wall formwork shall at all times be secured so that it will
not be toppled over by wind. Do not leave unsecured wall
formwork in a vertical position.
(iii) The faces and edges of formwork shall be clean and free
of projecting nails.
(iv) Formers for formwork profile, chamfers, splays , rebates
and other features shall be rigidly and firmly fixed to theformwork.
(v) Wood preservatives shall be applied to all surfaces of left
in timber formwork.
Left -in
formwork
(vi) Where the inclination exceeds 15 degrees from the
horizontal, formwork to the top surface shall be provided.
Sloping
formwork
(vii) All joints in formwork including joints between
formwork and completed work shall be closely fitted to
prevent leakage of grout. Gaps, if any, shall be sealed
with gasket, filler, sealant or tape before fixing
reinforcement.
Joints in
formwork
(viii) All joints in formwork shall be tightly secured against
completed work to prevent the formation of stepping or
ridges in the concrete.
(ix) Inserts or box-out to form holes and chases to specified
sizes and shapes shall be fixed in correct positions before
placing concrete.
Forming
holes and
chases
(x) Any device for securing formwork or falsework shall not
be allowed to remain within the specified concrete cover.
Fixing
devices
(xi) Formwork ties and components shall be fixed in such a
manner that they do not touch reinforcement or build-in
component. Any part left in the concrete shall be at least40mm or equivalent to the specified nominal cover to the
reinforcement, whichever is greater.
Formwork
ties and
components
(xii) Formwork ties and components shall be fitted tightly
against formwork faces such that no loss of grout occurs.
(xiii) Unless otherwise permitted by the SO, formwork ties and
components used with profiled formwork shall be a type
such that holes left by the ties and their components are
small enough to be completely located within the recesses
of the concrete surface.
(xiv) Where surface treatment requires bonded adhesion,
release agents shall not be used.
Use of release
agents
(xv) Formwork faces shall be cleaned before release agents
are applied. Concrete, reinforcement and built-in
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components shall not be contaminated by the release
agents.
(xvi) Temporary openings in the formwork for cleaning or
inspection shall be provided if required. Immediately
before concrete is placed in any section of the formwork,
the interior of that section shall be completely cleared of
all extraneous materials including water.
Cleanliness
Removal/ Dismantling of Formwork and FalseworkClause
6.11
Formwork and falsework shall be struck without disturbing,
damaging, or overloading the finished concrete work or the
structure.
Striking
Clause
6.12
Minimum periods for retaining formwork and falsework in
position before striking to be in accordance with Table 6.1.
Minimum
periods
before
striking
TABLE 6.1
Striking time
Type of formwork Concrete without PFA Concrete with
PFA
Vertical formwork to
columns, beams and walls
(unloaded)
24 hrs 30 hrs
Soffit formwork to slabs
(props left under)
3 days 4 days
Props to slabs (unloaded) 7 days 7 days
Soffit formwork to beams
(props left under)
7 days 7 days
Props to beams (unloaded) 16 days 16 days
Props to cantilevers 28 days 28 days
Inclined Formwork to top
surface
12 hrs 12 hrs
(i) These periods are for ordinary Portland cement, at 15Ctemperature. Increase these periods for lower
temperatures as instructed by the SO.
(ii) Where the props are to be left in place whilst the soffit
formwork to slabs and beams is to be removed, such
props shall either be designed to remain in position
throughout the striking process without having to be
temporarily removed or alternatively, if agreed by the SO,
be so designed that a few can be removed at a time and
replaced immediately.
(iii) Do not place construction loads on any unshored portionof the structure under construction. The number of floors
requiring propping is to be as instructed by the SO
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according to the design loads of such floors.
Clause
6.13
NOT USED
(existing) Clause
6.14
Steel reinforcement to be plain round steel bars....type 2 bond
classification to BS 4449 or hard drawn steel wire fabric toBS
4483.
Steel
reinforcement
replace with Steel reinforcement to be plain round steel or deformed high
yield steel bars to CS2 or hard drawn steel wire fabric to BS
4483.
Steel
reinforcement
(existing) Clause
6.15
Obtain steel reinforcement from suppliers who must be able to
produce certificate of routine testing showing the place of
origin and the routine test results for each consignment of steel
reinforcement supplied to site.
Test
certificate
replace with Obtain steel reinforcement from suppliers who must be able to
produce certificates for each consignment of steel reinforcement
supplied to site. The certificates to be submitted shall be inaccordance with the class of reinforcement delivered to site, all
as detailed in CS2.
Test
certificate
(existing) Clause
6.17
Provide and cut..... and rebend tests as required by BS 4449,
appropriately mark and ....
Alternatively the Contractor may, with the permission of the SO,
deliver test specimens to the laboratories of the following
institutions for testing:-
(i) University of Hong Kong
(ii) Hong Kong Polytechnic
Test certificates are to be sent to .....LaboratoriesAllow sufficient.......by the SO.
Test
specimens
replace with Provide and cut test specimens from each consignment as
directed by the SO for tensile tests, bend tests and rebend tests
as required by CS2, appropriately marked and delivered to PW
Laboratory for testing. No claim in respect of steel suffering
from damage or rod lengths being reduced due to the taking of
testing specimens will be entertained.
Alternatively the Contractor may deliver test specimens to the
laboratories approved by the SO.
Test certificates are to be sent to the SO directly from these
Laboratories.
Allow sufficient time......by the SO.
Test
specimens
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(existing) Clause
6.27
Ordinary and ......BS 12 : 1989. Cement
replace with Ordinary and ...... BS 12. Cement
(existing) Clause
6.42
.....
For liquid retaining structures, the minimum cementitious
content shall be 320 Kg/m
3
when the nominal......cement ratiobelow 0.5.
replace with ....
For liquid retaining structures, the design of the concrete mix
shall satisfy the following requirement:-
(i) Maximum Water/Cement ratio to be 0.45.
(ii) Minimum cementitious content to be 325 Kg/m3 .
(iii) Maximum cementitious content to be 400 Kg/m3 .
(iv) Slump should be greater than 75 mm.
(existing) Clause
6.42
TABLE 6.8
Minimum cementitious content (kg/m) and
maximum free water cement (W/C) ratio
Exposure Maximum
Plain concrete Reinforced concrete and
prestressed concrete
conditions aggregate
size
(mm)
Minimum
cementitious
content
Maximum
free W/C
ratio
Minimum
cementitious
content
Maximum
free W/C
ratio
Moderate 40 245 270
20 275 0.65 300 0.60
10 315 340
Severe 40 270 295
20 300 0.60 325 0.55
10 340 365
replace with Clause
6.42
TABLE 6.8
Minimum cementitious content (kg/m) and
maximum free water cement (W/C) ratio
Exposure MaximumPlain concrete Reinforced concrete and
prestressed concrete
conditions aggregate
size
(mm)
Minimum
cementitious
content
Maximum
free W/C
ratio
Minimum
cementitious
content
Maximum
free W/C
ratio
Moderate 40 245 300
20 275 0.65 300 0.60
10 315 340
Severe 40 270 300
20 300 0.60 325 0.55
10 340 365
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(existing) Clause
6.45
TABLE 6.9
Chloride content
Type of concrete
Maximum total chloride
content %
Prestressed concrete
Steam cured structural concrete
0.1
Reinforced concrete
Concrete with embedded metal
0.35
replace with Clause
6.45
TABLE 6.9
Chloride content
Type of concrete
Maximum total chloride
content %
Prestressed concrete
Steam cured structural concrete
0.1
Reinforced concrete made with
sulphate resisting Portland
cement
0.2
Reinforced concrete
Concrete with embedded metal
0.35
(existing) Clause
6.55
item (ii) (a)(b)
add (ii) (c) If the difference between the compressive strengths of
two test cubes made from one sample of designed mix
concrete exceeds 15% of the test result :
(i) the higher of the compressive strengths of the two test
cubes shall be used to assess compliance in Column
B of Table 6.12, and
(ii) the test result for that sample shall not be used to
assess compliance in Column A of Table 6.12 and
shall not be used to calculate the standard deviation.
(existing) Clause
6.55(iv)
When the calculated standard deviation ...... any
subsequent standard deviation calculation.
replace with If the standard deviation of a set of 40 consecutive test
results of concrete judged by the same compliance
criteria exceeds 5 MPa and does not exceed 8 MPa,
compliance requirement C1 shall apply to subsequent test
results. If the standard deviation exceeds 8 MPa, no
further concrete shall be placed in the permanent work
until an investigation of the materials, mix design,
methods of production, sampling and testing has been
carried out and measures have been taken which in the
opinion of the SO will result in restoring a satisfactory
standard of quality control.
add Clause If the compliance requirements are changed from C1 to C2 or
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6.55 (v) from C2 to C1, the new compliance requirements shall apply
from the 35th day after making the last pair of test cubes in the
set of 40 on which the decision to change was based. For the
purpose of calculating the average of any 4 consecutive test
results, test results immediately before and immediately after the
change shall be treated separately.
(existing) Clause6.55
item (v)
change item (vi)
(existing) Clause
6.55
item (vi)
change item (vii)
add Clause
6.55
(viii)
If designed mix concrete is considered as not complying with
the specified requirements for compressive strength, the SO may
instruct that tests as stated in Clauses 6.57 to 6.59 be carried out
on concrete cores or on samples taken from the hardened
concrete.
(existing) Clause
6.57 (ii)
The average estimated ...... in accordance withBS 6089 ......
replace with The average estimated ...... in accordance with CS 1 ......
(existing) Clause
6.58
Appropriately mark and deliver all concrete cubes and cores to
a PW Laboratory, as directed by the SO.
Testing and
test record
replace with Appropriately mark and deliver all concrete cubes and cores to a
PW Laboratory, unless ordered by the SO for projects in rural
areas.
Testing and
test record
(existing) Clause
6.63
Concrete for water tanks shall comply with the requirements in
Clause 6.43. Where no predetermined construction joints are
specified,.....
Water tanks
replace with Concrete for water tanks shall comply with the requirements in
Clause 6.42. Where no predetermined construction joints are
specified,.....
Water tanks
SECTION 8
CONCRETE FOR MINOR AND
NON-STRUCTURAL WORK
(existing) Clause
8.03
Ordinary Portland cement shall be to BS 12 : 1989.
replace with Ordinary Portland cement shall be to BS 12.
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SECTION 9
BRICK WORK AND BLOCK WORK
(existing) Clause
9.05
Fire bricks to be imported fire clay refractionary bricks of
specified class to BS 1758, of the best quality, light in colour,
uniform in texture and of standard sizes to BS 3056. Testing, if
specified shall be toBS 1902
Fire bricks
replace with Fire bricks to be imported fire clay refractionary bricks ofspecified class of the best quality, light in colour, uniform in
texture and of standard sizes to BS 3056. Testing, if specified
shall be to BS 1902
Fire bricks
(existing) Clause
9.13
Damp proof courses to be 2 layers of 2 layers of 2-ply
bituminous paper or of other types to BS 743. Do not use
hessian based types of bitumen damp proof courses.
Damp proof
course
replace with Damp proof courses to be 2 layers of 2-ply bituminous paper or
of other types to BS 743. Do not use hessian based types of
bitumen damp proof courses.
Damp proof
course
SECTION 10
MASONRY
(existing) Clause
10.01
Stone, generally, to be imported/local granite, of consistent
colour, free from defects that will adversely affect strength or
appearance and complyBS 5390.
Stone
replace with Stone, generally, to be imported/local granite, of consistent
colour, free from defects and ferrous materials that will
adversely affect strength or appearance and comply BS 5390.
Stone
(existing) Clause
10.05
Ties between walls and concrete to be copper or bronze not less
than 40mm wide, 3mm thick and 150mm long and fanged both
ends.
Wall ties
replace with Ties between walls and concrete to be copper, bronze or
stainless steel to BS 1243 not less than 40mm wide, 3mm thick
and 150 mm long and fanged both ends.
Wall ties
(existing) Clause
10.09(b)
Square rubble - Trim stones roughly square 75 to 300mm high,
varying in 75mm stages. Each stone to be 100 to 150mm deepand 100 to 600mm long on bed. Length or depth on bed of each
stone to be greater than the height.
replace with Square uncoursed rubble - Trim stones roughly square 75 to
300mm high, varying in 75mm stages. Each stone to be 100 to
150mm deep and 100 to 600mm long on bed. Length or depth
on bed of each stone to be greater than the height
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(existing) Clause
10.15
Where squared rubble walls exceed 300mm think Square rubble
exceeding
300mm thick
replace with Lay square rubble walls in random sizes (see diagram) where
walls exceed 300mm thick.
Square
rubble walls
Additional
Clause
Clause
10.15A
Lay roughly hammer pitched stones with no pronounced
lamination, to irregular polygonal shapes, and bedded to showthe joints running in all directions (see diagram F & G).
Polygonal
rubblewalling or
Kentish
Rag.
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SECTION 11
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TANKING
(existing) Clause
11.02
For asphalt tanking, the work ....................... Specialist
contractor
replace with For sheet membrane tanking, the work shall be executed by the
manufacturers approved specialist contractor.
Specialist
contractor
SECTION 12
ROOFING
(existing) Clause
12.51
All asphalt roofing for repair works to existing asphalt roofs
shall be laid and executed complete by an approval contractor
on the LWB List for Asphalt Roofing and Tanking.
replace with All asphalt roofing for repair works to existing asphalt roofs
shall be laid and executed complete by an approved contractor
for Asphalt Roofing and Tanking.
(existing) Clause
12.75
4th line : ......... electro-planted.........
replace with ...... electro-plated ......
(existing) Clause
12.79
Fix to steelworks with self tapping screws designed for fixing to
steel. Fix to timber....
Fixing
sheeting
replace with Fix to steelworks with stainless steel self tapping screws
designed for fixing to steel. Fix to timber....
Fixing
sheeting
(existing) Clause
12.80
Cut, fit and dress steel sheet accessories to fit corrugations or
profiles. Where possible, fix with same fixings that secure the
sheeting. Elsewhere, fix to the sheeting with roofing bolts.
Fixing
accessories
replace with Cut, fit and dress steel sheet accessories to fit corrugations or
profiles and fix with approved fixings in accordance with the
manufacturers recommendations.
Fixing
accessories
additional Clause
12.83A
Treat joints of steel corrugated sheet roof according to Clause
12.34.
Waterproof
joints of steelsheet roofing
(existing) Clause
12.99
3rd line : ......... Approved Specialist Roofing Materials
Contractors .........
replace with ......... Acceptable Specialist Roofing Materials/Applicators
(existing) Clause
12.100
2nd line : ......... approved .........
replace with ......... acceptable .........
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SECTION 13
CARPENTRY AND JOINERY
(existing) Clause
13.21
Laminated plastic sheet to BS 438. Class HG (Horizontal-
General Purpose) or VG (Vertical-General Purpose) as
specified.
Laminated
plastic
replace with Laminated plastic sheet to BSEN 438. Class HG (Horizontal-
General Purpose) or VG (Vertical-General Purpose) as
specified.
Laminated
plastic
sheet
(existing) Clause
13.23
The suspension system shall be an approved proprietary system
meeting the requirement of CP 290 manufactured from one of
the following materials.
(i) Galvanised mild steel.
(ii) Aluminium.
(iii) A combination of galvanised mild steel and aluminium.
Proprietary
suspended
ceiling
systems
replace with The suspension system shall be an approved proprietary systemmeeting the requirements ofCP 290 manufactured from one of
the following materials.
(i) Galvanised mild steel.
(ii) Aluminium.
(iii) A combination of galvanised mild steel and aluminium.
Proprietarysuspended
ceiling
systems
(existing) Clause
13.50
Ensure the base is clean and dry. Lay blocks on one coat of an
approved cold bitumen rubber emulsion adhesive applied to the
screed with a serrated trowel. Leave flooring ready to receive
sealer or polish. Sand surface of parquet flooring as Clause13.50.
Parquet
flooring
replace with Ensure the base is clean and dry. Lay blocks on one coat of an
approved cold bitumen rubber emulsion adhesive applied to the
screed with a serrated trowel. Leave flooring ready to receive
sealer or polish. Sand surface of parquet flooring as Clause
13.49.
Parquet
flooring
page 233 Clause
13.57
sub-para (ii) should read Clause 13.56.
SECTION 14IRONMONGERY
Clause
14.35
sub-para. (j) penultimate line should read in pre-bored.
Clause
14.36
first line should read fittings shall be.
SECTION 15
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STRUCTURAL STEEL WORK
(existing) Clause
15.03
Structural steelwork shall comprise weldable structural steel to
BS 4360 grade 43A (mild steel) or grade 50B (high yield steel).
Mechanical
properties and
chemical
composition
replace with Structural steelwork shall comprise weldable structural steel toBS 4360 grade 43A, grade 43C or 43D(for hollow section only)
or grade 50 B.
The use of weldable cold - formed structural hollow sections
shall comply with BS 5950 Part 5, BS 5950 Part 7 andBS 6363.
Mechanicalproperties
and chemical
composition
(existing) Clause
15.22
Carry out welding in accordance with the requirements ofBS
5135. Welding to be manual metal-arc welding unless
otherwise specified.
Welding
replace with Welding shall be a metal arc process in accordance withBS5135 together with other clauses contained in the GS, unless
otherwise specified.
Welding consumables used shall be chosen to ensure that the
mechanical properties of the weld metal are not less than those
required for the parent metal.
Welding
(existing) Clause
15.23
Provide an experienced and competent operator to supervise
welding. Submit certificates proving that all welders have
passed the training tests inBS 1295 and if specified, carry out
approval tests to BS 4871:Pt.1 or BS 4872 : Pt. 1 as
applicable.
Welders and
testing of
welders
replace with Provide an experienced and competent operator to supervise
welding. Welders shall be tested to meet the requirements of
BSEN287 Part 1 but, in the case of welders engaged on fillet
welding only, BS4872 Part 2 is an acceptable alternative.
Test on welders shall be witnessed by a qualified welding
inspector and certificates endorsed by an independent inspection
authority. The certification shall remain valid providing it
complies with the conditions for re-approval of certificationspecified in BSEN 287 Part 1.
Welders and
testing of
welders
(existing) Clause
15.25
Obtain approval of the proposed welding procedures prior to
commencing welding including:
(i) Preparation of fusion faces.
(ii) Preheating temperature where required.
(iii) Type of electrodes.
(iv) Number and sequence of runs to build-up the weld
bead.
(v) Post-heating treatment if required.Do not depart from the agreed welding procedure without the
prior agreement of the SO.
Welding
procedures
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replace with Submit welding procedures which are to be prepared and
certified by a qualified welding inspector. Obtain approval of
the proposed welding procedures prior to commencing welding
including:
(i) Welding process or processes when more than one is
used in making a complete joint,
(ii) Parent metal specification, thickness and other relevantdimensions,
(iii) Classification, type and size of electrodes and other
consumables,
(iv) Welding current, arc voltage and welding speed,
(v) Sketch showing edge preparation, fit-up and
approximate number and arrangement of runs in multi-
run welds,
(vi) Minimum preheating temperature and interpass
temperature range,
(vii) Post-weld heat treatment if required.
Do not depart from the agreed welding procedure without prior
agreement of the SO.
Welding
procedures
(existing) Clause
15.26
Carry out approval ...... BS 4870 :Pt. 1 when specified ...... Approval
testing of
welding
replace with Carry out approval ...... BSEN 288-3 when specified ...... Approval
testing of
welding
(existing) Clause
15.35
Where specified, test welded joints by radiographic methods to
BS 2600 :Pt. 1 and Pt. 2 with the type of film specified by the
SO or by ultrasonic methods to BS 3923 :Pt. 1 and Pt. 2 to
ascertain that the joint is free from flaw, cracks or other
imperfections. Employ an approved specialist firm to carry out
and interpret these tests and provide any necessary labour and
attendance. The testing programme and the standard of
acceptance shall be approved. Should test results indicate that
welds are below the standard of acceptance, carry out approved
remedial measures and further acceptance tests.
Acceptance of
welds
replace with Employ an approved specialist firm to carry out and interpret
the inspection and testing, and provide any necessary labour and
attendance. Submit evidence proving that operators carrying
out the inspection and testing have been trained and assessed for
competence in the inspection and testing of welds. In addition,
submit certificates of competence from a recognised authority
for operators carrying out ultrasonic examination.
Submit testing programme for the approval of SO. Any weldswhich will be rendered inaccessible by subsequent work shall be
examined prior to the loss of access.
Acceptance of
welds
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All welds shall be visually inspected in accordance with
BS5289. Non-destructive testing shall be carried out after
visual inspection in accordance with the table below :
Weld Type Frequency of Non-destructive Testing
All types of butt
welds
100% ultrasonic examination
and magnetic particle flaw detection
Fillet welds with leglength exceeding
and including
10mm
20% ultrasonic examinationand magnetic particle flaw detection
Fillet welds with leg
length not
exceeding 10mm
20% magnetic particle flaw detection
Secondary
attachment welds,
e.g. for fixing
purlins, side rails
5% of attachments by magnetic particle
flaw detection and ultrasonic examination
if leg length exceeds and includes 10mm
The standard of acceptance for butt welds shall be in
accordance with Table 18 quality category A ofBS5135. The
standard of acceptance for fillet welds and secondary
attachment welds shall be in accordance with Table 2 in the
Appendix of the Practice Note for Authorized Persons and
Registered Structural Engineers PNAP 160.
Ultrasonic examination shall be carried out in accordance with
BS3923: Part 1 Level 2B. Magnetic particle flaw detection
shall be carried out in accordance with BS6072. Examinationshall be carried out not less than 16 hours from the time of
completion of the weld to be inspected, or not less than 40 hours
in the case of butt welds thicker than 40mm or any welds to
Grade 55 steels.
Should test results indicate that welds are below the standard of
acceptance, carry out at the Contractors own expense approved
remedial measures and further acceptance tests.
(existing) Clause
15.39
Apply hot dip galvanized coatings ...... as specified in the
contract.
Hot dip
galvanizing
replace with Prior to galvanizing, the following requirements have to be
satisfied :
Hot dip
galvanizing
(i) All welding slags and paints on the steel surface shall be
removed.
(ii) All cut surfaces shall be ground smooth.
(iii) Adequate number of vent holes shall be provided for
closed end hollow sections, and
(iv) Drainage holes shall be provided at joints where free flowof molten zinc would otherwise be impossible, e.g. joints
between stiffeners and I sections.
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Apply hot dip galvanized coatings ...... as specified in the
contract.
(existing) Table
15.3
Type A Primer: Lead based primer toBS 2523 or
drying oil based zinc phosphate
primer
replace with Type A Primer: Drying oil based zinc phosphate
primer
(existing) Table
15.3
Type B Primer: Lead based primer toBS 2523 or
drying oil based zinc phosphate
primer
replace with Type B Primer: Drying oil based zinc phosphate
primer
SECTION 16
CURTAIN WALLS
(existing) Clause
16.47
(iii)(a)
Perpendicular to the plane of the wall, net deflection from
framing members
replace with Perpendicular to the plane of the wall, net deflection of framing
members
SECTION 17
METALWORK
(existing) Clause
17.06
Cast iron to be grey cast iron to BS 1452 Grade 150. Cast Iron
replace with Cast iron to be grey cast iron to BS 1561 Grade 150. Cast Iron
(existing) Clause
17.07
Aluminium alloy plate, sheet and strip to be to BS 1470, of the
required alloy designation.
Aluminium
alloy
replace with Aluminium alloy plate, sheet and strip to be to BSEN 485, 515,573, of the required alloy designation.
Aluminiumalloy
(existing) Clause
17.08
Brass rods and sections to be to BS 2874 designation CZ 106
condition M.
Brass rods
and sections
replace with Brass rods and sections to be to BSEN 12163, 12164, 12167
designation CZ 106 condition M.
Brass rods
and sections
(existing) Clause
17.18
Welding of stainless .......................... subject to approval. Welding of
stainless steel
replace with Welding of steel to be by manual metal-arc welding to BS 5135.Welding of stainless steel to be inert-gas arc welding to BS
7475 or other method subject to approval.
Welding ofstainless steel
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(existing) Clause
17.21
(c)
Zinc sprayed coating to be to BS 2569: Part 1 - nominal
thickness 0.2 mm unless otherwise specified.
Finishes to
steel
replace with Zinc sprayed coating to be to BSEN 22063: Part 1 - nominal
thickness 0.2 mm unless otherwise specified.
Finishes to
steel
(existing) Clause17.21
(d)
Galvanising to be .............................................. if required.
replace with Galvanising to be hot-dip galvanising to BS 729 with a
minimum thickness of 85 m. Components to be galvanised
after fabrication, if required.
(existing) Clause
17.32
Steel windows and .............................................. in accordance
with the following :-
Steel windows
and doors
(a) Unless otherwise .......................................... prior to delivery to
Site.
replace with Steel windows and doors shall be constructed to BS 6510 and inaccordance with the following :-
(a) When fixed in position, windows and doors shall be designed to
withstand a wind load calculated in accordance with the Code
of Practice on Wind Effects, Hong Kong with a minimum
pressure of 3 kPa and a permissible maximum deflection of
1/180th of the length of the member under consideration.
Calculations are required to be submitted for approval.
(existing) Clause
17.32
(n) When specified, ................................................ and closing
high windows.replace with (n) When specified, high openable windows in inaccessible
locations to be fitted with remote control gear.
(existing) Clause
17.33
Aluminium windows and doors shall be obtained from a
manufacturer on the LWB List for Aluminium Windows, Doors
and Flyscreens and constructed in accordance with the
following: -
Aluminium
windows and
doors
replace with Aluminium windows and doors shall be obtained from a
approval manufacturer and construction in accordance with the
following: -
Aluminium
windows and
doors
(existing) Clause
17.33
(a) When fixed in position ................................................
brackets, etc. as stiffeners..
replace with (a) When fixed in position, windows and doors shall be
designed to withstand a wind load calculated in
accordance with the Code of Practice on Wind Effects,
Hong Kong with a minimum pressure of 3kPa and a
permissible maximum deflection of 1/180th of the length
of the member under consideration. Where necessary use
mild steel cores, anchors, brackets, etc. as stiffeners.Calculations are required to be submitted for approval.
Cores, anchors and brackets etc. shall be finished to
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Clause 17.33(p).
(existing) Clause
17.33
(e) Provide ....................................... lug
spaces............................... fixing bolts.
replace with (e) Provide ........................................ lugs spaced
............................... fixing bolts.
deleted Clause17.33
(g) to be deleted
(existing) Clause
17.33
(l)(ii)(a) diecast zinc alloy toBS 1004 suitably
coloured to match the anodised window or door
metal.
replace with (a) diecast zinc alloy to BSEN 1774 suitably coloured to
match the anodised window or door metal.
(existing) Clause
17.41
Roller shutters and ........................................ with the following
:-
Roller
shutters anddoors
(a) Steel roller shutters ...................................... shutter
against wear.
replace with (a) Roller shutters and doors shall be supplied and fixed in
accordance with the following :-
Steel roller shutters shall consist of horizontal hot dipped
galvanised slats which interlock through their entire length
to form a continuous hinge. The shutters shall be designed
to withstand a wind load calculated in accordance with the
Code of Practice on Wind Effects, Hong Kong with aminimum pressure of 3 kPa on the entire surface area of the
shutter or otherwise specified.
Roller
shutters and
doors
(existing) Clause
17.41
(d) Electrically operated shutters
.......................................... by the Architectural
Services Department.
replace with (d) Electrically operated shutters shall comply with the
Code of Practice for Installation of Electrically Operated
Sliding Gates, Sliding Glass Doors and Rolling Shutterspublished by the Electrical and Mechanical Services
Department. The shutters shall be installed complete with
electric motors, the associated overload protection, drive
mechanism, limit switches, emergency stop, control buttons and
other control devices required by the shutter manufacturer. The
electrical installation of the shutter shall comply with BS7671:
Regulations for Electrical Installations and the General
Specification for Electrical Installations in Government
Buildings, Hong Kong.
(existing) Clause17.41
(n) An interlock switch .......................................... movingpart of the roller shutters.
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replace with (n) An interlock switch shall be provided to prevent the
locked roller shutters from operating electrically and
shall be fitted on a stationary part (such as the guide
rails) but not on the moving part of the roller shutters.
(existing) Clause
17.42
Fire resisting roller shutters shall satisfy the requirements of
BS 476:Part 8 for the specified period of resistance required.
The shutters shall be self-closing activated by fusible links or
electronic heat or smoke detectors. Test certificates will be
required.
Fire resisting
roller shutters
replace with Fire resisting roller shutters shall satisfy the requirements of
BS 476: Parts 20-23 for the specified period of resistance
required. The shutters shall be self-closing activated by fusible
links or electronic heat or smoke detector s. Test certificates
will be required.
Fire resisting
roller
shutters
(existing) Clause
17.43
The design of the roller ............................................... defective
materials, workmanship or design.
Design and
manufacturer
of rollershutters
replace with The design of the roller shutters, including boxes, hoods, guides
and all other parts shall be the responsibility of the Contractor.
Design and
manufacturer
of roller
shutters
SECTION 18
FINISHES (INCLUDING CARPETING AND RAISED FLOORING)
(existing) Clause18.04
Lime to be as Clause 6.18. Lime
replace with Lime to be as Clause 9.18. Lime
(existing) Clause
18.05
Lime putty to be as Clause 6.19. Lime patty
replace with Lime putty to be as Clause 9.19. Lime patty
(existing) Clause
18.06
Admixtures and additives to be as Clause 6.19. Admixtures
and additives
replace with Admixtures and additives to be as Clause 6.36. Admixtures
and additives
(existing) Clause
18.08
Mix mortar or plaster as Clauses 6.21 to 6.23. Mixing
mortar of
plaster
replace with Mix mortar or plaster as Clauses 9.21 to 9.23. Mixing
mortar of
plaster
(existing) Clause
18.09
Provide sample panels of about 1 sq m2
for -------
replace with Provide sample panels of approximately 2 sq m2 for -------
(existing) Clause Apply spatterdash to concrete vertical surfaces and soffits Spatterdash
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18.15 immediately after striking formwork. Mix and apply as follows:
-
(i) Mix to consist of cement and coarse sand or granite fines in
the proportion of 1: 2.
(ii) Throw onto a thickness not exceeding 6 mm with a hand
scoop or a trowel and wet one hour after application.
(iii) Allow to cure and harden before applying undercoat.
replace with Clean all laitance, dust, oil or any other such substances from
the concrete surface.
Spatterdash to consist of (1:2) cement : coarse sand or granite
fines with an approved bonding agent such as a styrene-
butadiene rubber (SBR) latex, an ethyl vinyl acetate (EVA)
emulsion or an acrylic emulsion.
Apply spatterdash to concrete vertical surfaces and soffits
immediately after striking formwork.
The mixture shall be applied by dashing it on the wall to give a
complete coverage with a rough texture between 2 to 3 mm
thickness. The surface shall be maintained moist for 24 hours.
(iv) Allow to cure and harden for at least two days before
applying rendering / bedding screed.
Spatterdash
(existing) Clause
18.21
---- layer of damp sand. Keep covered for 7 days. Curing of
floor finishes,
etc.
replace with ---- layer of damp sand. Unless otherwise agreed by the SO,
keep covered for 7 days.
Curing of
floor finishes,
etc.
(existing) Clause
18.22
Movement joints are to be constructed at approximately 3m
centres in each direction equally spaced, in accordance with
Clauses 4.55 and 4.56, or as directed by the SO to accord with
dimensioned requirements.
Sealing
movement
joints
replace with Movement joints are to be constructed at a maximum 4m
centres in each direction equally spaced, in accordance with
Clauses 6.61 and 6.62, or as directed by the SO to accord with
dimensioned requirements.
Movement
joints
(existing) Clause
18.37
Fire cement to be as specified for firebrick mortar in Clause
6.21.
Fire cement
replace with Fire cement to be as specified for firebrick mortar in Clause
9.21.
Fire cement
(existing) Clause
18.46
Apply external rendering consisting of cement, lime and sand in
two coats as follows: -
External
render
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(i) First coat 10mm (minimum) thick - mix 1:2:6.
(ii) Finishing coat 10mm (maximum) thick - mix 1:3:6, with
textured finish.
Total thickness of external render is not to exceed 20mm.
replace with Clause
18.46
Apply external rendering to spatterdashed surfaces consisting of
cement and sand in two coats as follows:-
(i) Undercoat 10mm (minimum) thick --- mix 1:3
(ii) Finishing coat 10mm (maximum) thick --- mix 1:3, with
textured finish. Total thickness of spatterdash & external
rendering shall not exceed 20mm.
Undercoat must be thoroughly dry before application of the
finishing coat.
Pulverised Fly Ash (PFA) shall not be used for the external
rendering.
External
render
Add Clause
18.47
Pulverised Fly Ash (PFA) shall not be used for the internal
plastering.
(existing) Clause
18.103
(i) (d) Lay tiles and tamp firmly into bed with -----
replace with (i) (d) Lay tiles mixed from six boxes and tamp firmly into bed
with -----
(existing) Clause
18.103
(ii) (d) Lay tiles and tamp firmly into bed with -----
replace with (ii) (d) Lay tiles mixed from six boxes and tamp firmly into bed
with -----
(existing) Clause
18.107
(i) (a) Soak tiles in clean water for 30 minutes ----
replace with (i) (a) Soak tiles, mixed from six boxes, in clean water for 30
minutes ----
(existing) Clause18.107
(ii) (a) If approved, fix wall tiles using a bed of adhesive in ----
replace with (ii) (a) If approved, fix wall tiles, mixed from six boxes, using a
bed of adhesive in ----
(existing) Clause
18.108
Fixing of external facing tiles to be as Clause 18.107 except
width of joints to be as specified.
Fixing
external
facing tiles
replace with Fix external wall tiles to spatterdashed surfaces as follows:-
(i) Thick bed method:-
(a) Apply wall screed of (1:3) cement : sand to a maximum
thickness of 10 mm. Allow the wall screed to dry off
thoroughly.
Fixing
external
facing tiles
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(b) Soak tiles in clean water for 30 minutes. Stack to drain and
fix as soon as the surface water has drained off.
(c) Apply a mortar slurry of (1:3) cement : sand with
water/cement ratio of 0.5 by weight to thickness of 10 mm
on the wall screed.
(d) The bedding surface of the tile shall be pre-filled with the
mortar slurry before fixing to the wall screed.
(e) The tile must be affixed by trowel knock procedures. Knock
the centre of tile using the handle of a trowel first and
followed by knocking all the edges of a tile till the mortar
slurry flows out from the tile edges.
(f) Joints to be minimum 2 mm wide, and maximum 3.5mm
wide.
(g) Make any adjustment to tiles within 10 minutes of fixing.
(h) Clean tiles and joints before the slurry hardens.
(i) Grout joints minimum 24 hours after fixing tiles. Clean off
surplus grout as work proceeds.
(j) Clean tiles at completion.
(ii) Thin bed method:-
(a) Apply wall screed of (1:3) cement : sand to a maximumthickness of 10 mm. Allow the wall screed to dry off
thoroughly.
(b) Fix wall tiles to the wall screed using an approved adhesive
in accordance with the manufacturer's recommendations.
(c) Grout joints using an approved grout.
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Carry out infra-red thermographic scanning by an approved
specialist and submit report within 4 months upon completion
of external tiling. Should the report indicate that any part of the
wall tiling has not been affixed properly, the Contractor shall
carry out approved remedial measures at his own expense and
carry out further infra-red thermographic scanning to the
satisfaction of the SO.
(existing) Clause
18.111
Fix stone wall slabs not less than 12mm from the structural
surfaces on Keenes cement or Plaster of Paris dabs. Space
slabs so that each slab is evenly supported by not less than five
dabs. Dowel for and fit each slab with copper cramps and S
hooks, formed from 5mm diameter copper wire. Fix slabs at
approximately 350mm centres or as directed and solidly bed
cramps to the structure and S hooks to backs of slabs.
Fixing stone
wall slab
replace with Generally fix stone wall slabs in accordance with Clause 16.09,
16.14 and 16.15 for heights greater than 1.2 metre above anystructural floor level. Fix stone wall slabs not less than 12mm
from the structural surfaces on Keenes cement or Plaster of
Paris dabs. Space slabs so that each slab is evenly supported by
not less than five dabs. Dowel for and fit each slab with copper
cramps and S hooks, formed from 5mm diameter copper wire.
Fix slabs at approximately 350mm centres or as directed and
solidly bed cramps to the structure and S hooks to backs of
slabs.
Fixing stone
wall slab
(existing) Clause18.126 All carpet shall be of approved type and colour and inaccordance with the following specification, of an approved
brand, laid and executed by a specialist on the Works Branch
List for Flexible Finishes.
Approvalbrands and
specialist
contractors
replace with All carpet shall be of approved type and colour and in
accordance with the following specification, of an approved
brand, laid on screed treated with an approved sealant to reduce
dust and pollution.
Approval
brands and
specialist
contractors
SECTION 19
PLUMBING(existing) Clause
19.01
All plumbing and above ground drainage work is to be in
compliance with the Water Authoritys requirements
Generally
replace with All plumbing is to be in compliance with the Water Authoritys
requirements and Waterworks Regulations
Generally
(existing) Clause
19.07
Plug to be as Clause 13.20 Plugs
replace with Plug to be as Clause 13.28 Plugs
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(existing) Clause
19.08(f
)
Pipe thread tape to be unsintered PTFE tape to BS4375 of an
approved proprietary brand.
replace with Pipe thread tape to be unsintered PTFE tape to BS7786 of an
approved proprietary brand.
(existing) Clause
19.11
Fix pipes and fittings securely with fixings and fastenings
appropriate to the locations and the material (refer to Tables
15.1 and 15.2). Avoid pipe runs above electrical switchgear.
Fixing pipes
replace with Fix pipes and fittings securely with fixings and fastenings
appropriate to the locations and the material (refer to Tables
19.1 and 19.2). Avoid pipe runs above electrical switchgear.
Fixing pipes
(existing) Clause
19.18
Where pipes pass through fire rated walls or floors to be as
Clause 19.13 but :-
Pipe through
fire rated
walls and
floors
replace with Where pipes pass through fire rated walls or floors to be as
Clause 19.17 but :-
Pipe through
fire rated
walls and
floors
(existing) Clause
19.23
Avoid contact between certain dissimilar metals as Clause
17.27.
In particular avoid the direct contact of copper with galvanized
iron or steel pipes.
Contact
between
dissimilar
metals
replace with Avoid contact between certain dissimilar metals in particular
avoid the direct contact of copper with galvanized iron or steel
pipes as Clause 17.26.
Contact
between
dissimilar
metals
(existing) Clause
19.40
The whole clause is deleted.
(existing) Clause
19.41
Screw threads to UPVC pipes are not allowed unless ordered
otherwise by the SO. Where screw connections are required,
screwed adapter bushes shall be used.Fix and joint plastic pipes