HYD/F/081
Merchants’ House North
Wapping Road
Bristol BS1 4RW
Tel: 0117 945 9225
Fax: 0117 930 0692
www.hydrock.com
Structural Engineering
Specification
C14821: White Rock
Innovation Centre
Revision History:
Rev R01: 03.10.14: Issued for Review
Date: 3rd October 2014
Registered Office:
Hydrock Consultants Limited
Over Court Barns
Over Lane Almondsbury
Bristol BS32 4DF U.K.
Registered in England No: 3118932
White Rock Innovation Centre Structural Engineering
Specification
03 October 2014
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Table of Contents
Title
Page
D
Groundwork
3
D20
Excavating and filling
4
E
In situ concrete/Large precast concrete
11
E05
In situ concrete construction generally
12
E10
Mixing/casting/curing in situ concrete
15
E20
Formwork for in situ concrete
23
E30
Reinforcement for in situ concrete
27
E40
Designed joints in in situ concrete
30
E41
Worked finishes to in situ concrete
32
E60
Precast/ composite concrete floors/ roof decks
34
G
Structural/Carcassing metal/timber
37
G10
Structural steel framing
38
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D
Groundwork
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D20
Excavating and filling
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D20 Excavating and filling
To be read with Preliminaries/General conditions
GENERALLY/THE SITE
150
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•
•
EXISTING SERVICES, FEATURES AND STRUCTURES
Services: See section A12 for locations.
Site features to be retained: See section A12 for details.
Structures: See section A34 for details of protection.
CLEARANCE/EXCAVATING
164
•
TREE ROOTS
Protected area: Do not cut roots within precautionary protection area.
Size of area: see arborist's report with root protection area and exclusion zone.
Excavation in protected area:
Method: By hand.
Backfill as soon as possible or temporarily line with polyethylene sheet to reduce
evaporation.
Outside protected area: Give notice of roots exceeding 25 mm and do not cut without
approval.
Cutting:
Make clean smooth cuts with no ragged edges.
Pare cut surfaces smooth with a sharp knife.
Treatment of cut roots: Not required.
Backfill: As dug material, enriched with phosphate fertilizer.
•
•
•
SITE CLEARANCE
Timing: Before topsoil stripping, if any.
General: Clear site of rubbish, debris and vegetation. Do not compact topsoil.
Treatment: none required.
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•
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168
170
REMOVING SMALL TREES, SHRUBS, HEDGES AND ROOTS
Identification: Clearly mark trees to be removed.
Small trees, shrubs and hedges:
Cut down.
Roots: Grub up and dispose of without undue disturbance of soil and adjacent areas.
• Safety: Comply with HSE/ Arboriculture and Forestry Advisory Group safety leaflets.
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180
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220
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CHIPPING AND SHREDDING
Generally: Permitted, remove arisings from site.
STRIPPING TOPSOIL
General: Before beginning general excavation or filling, strip topsoil from areas where there
will be regrading, buildings, pavings/ roads and other areas shown on drawings.
Depth:
Remove to an average depth of full depth, to suit battered excavations for foundations.
Give notice where the depth of topsoil is difficult to determine.
Handling: Handle topsoil for reuse or sale in accordance with clause 225.
Around trees: Do not remove topsoil from below the spread of trees to be retained.
Site storage: Keep separate from excavated sub-soil.
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221
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225
TREATING TOPSOIL
Treatment: Apply a suitable translocated nonresidual herbicide.
Timing: Not less than two weeks before excavating topsoil.
HANDLING TOPSOIL
Standard: To BS 3882.
Aggressive weeds:
Species: Included in the Weeds Act, section 2 or the Wildlife and Countryside Act,
Schedule 9, part II.
Give notice: Obtain instructions before moving topsoil.
• Contamination: Do not mix topsoil with:
Subsoil, stone, hardcore, rubbish or material from demolition work.
Other soil or material containing aggressive weeds, sharps, plastics and non soil forming
materials and notifiable animal or plant diseases.
Oil, fuel, cement or other substances harmful to plant growth.
Other classifications of topsoil.
• Multiple handling: Keep to a minimum. Use topsoil immediately after stripping.
•
•
240
ADJACENT EXCAVATIONS
Requirement: Where an excavation encroaches below a line drawn at an angle from the
nearest formation level of another higher excavation, the lower excavation, all work within it
and backfilling thereto must be completed before the higher excavation is made.
• Angle of line below horizontal: 40°.
• Backfill material: Hardcore filling as clause 710.
•
244
EXCAVATIONS ADJACENT TO EXISTING FOUNDATIONS
Prior to commencing excavation:
Excavate trial pits adjacent to existing foundations to determine extent and formation
levels.
Allow for inspection of trial pits.
Allow time for amendment of details if required.
Time period: 5 working days.
• Backfill material to new excavation: As clause 710.
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250
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260
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270
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PERMISSIBLE DEVIATIONS FROM FORMATION LEVELS
Beneath mass concrete foundations: ±25 mm.
Beneath ground bearing slabs and r.c. foundations: ±15 mm.
Embankments and cuttings: ±50 mm.
Ground abutting external walls: ±50 mm, but such as to ensure that finished level is not
less than 150 mm below dpc.
INSPECTING FORMATIONS
Give notice: Make advance arrangements for inspection of formations for foundations and
filling formations.
Notice (minimum): 3 working days.
Preparation: Just before inspection remove the last 150 mm of excavation.
Trim to required profiles and levels, and remove.
Loose material: Remove.
Seal: Within 4 hours of inspection, seal formations with concrete.
FOUNDATIONS GENERALLY
Give notice if:
A natural bearing formation of undisturbed subsoil is not obtained at the depth shown on
the drawings.
The formation contains soft or hard spots or highly variable material.
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285
STEPS IN FOUNDATION FORMATIONS
Depth of formation below ground level (minimum):
Existing ground level: 900mm.
Finished ground level: As drawings.
• Step dimensions:
Distance between steps (minimum): 900.
Height of step (maximum): 450.
Length of overlap (minimum): 2x height of step.
•
290
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•
310
FOUNDATIONS IN MADE UP GROUND
Depth: Excavate down to a natural formation of undisturbed subsoil.
Discrepancy: Give notice if this is greater or lesser than depth given.
UNSTABLE GROUND
Generally: Ensure that the excavation remains stable at all times.
Give notice: Without delay if any newly excavated faces are too unstable to allow
earthwork support to be inserted.
• Take action: If instability is likely to affect adjacent structures or roadways, take appropriate
emergency action.
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320
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330
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335
RECORDED FEATURES
Recorded foundations, beds, drains, manholes, etc: Break out and seal drain ends.
Contaminated earth: Remove and disinfect as required by local authority.
UNRECORDED FEATURES
Give notice: If unrecorded foundations, beds, voids, basements, filling, tanks, pipes,
cables, drains, manholes, watercourses, ditches, etc. not shown on the drawings are
encountered.
NEW FOUNDATIONS CROSSING OLD FOUNDATIONS OR WALLS
Break out: The old foundation/ wall where it crosses the new foundation/ wall:
Length of breaking out: Width of the new foundation/ wall plus 450 mm on either side of
new foundation.
Depth of breaking out: As necessary to permit the construction of the new foundation to
its design cross section.
• Disturbed/ softened soil: When the formation for the old foundation/ wall is deeper than the
formation of the new foundation.
Excavate: Soil that has been disturbed and/ or softened on either side of the old wall/
foundation, and for 300mm into undisturbed ground on either side.
• Step up: The formation for the new foundation as necessary on either side of the old
foundation/ wall until the formation is at its design level.
Size of steps: As clause 285.
• Backfilling beneath design formation level: Lean mix concrete.
•
337
OLD FOUNDATIONS OR WALLS BENEATH NEW GROUND SUPPORTED SLAB
Break out: The old foundation/ wall to a depth below the slab formation level of at least 150
mm.
Excavate: Soil that has softened on either side of the old wall/ foundation.
• Backfill: Obtain instructions if depth of fill will be greater than 600 mm, otherwise backfill
with compacted hardcore.
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350
•
EXISTING WATERCOURSES
Diverted watercourses which are to be filled: Before filling, remove vegetable growths and
soft deposits.
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360
EXCESS EXCAVATION
Excavation taken wider than required:
Backfill: With hardcore as clause 710.
• Excavation taken deeper than required:
Backfill: lean mix concrete.
•
DISPOSAL OF MATERIALS
415
•
450
EXCAVATED TOPSOIL REMOVAL
General: Remove from site.
WATER
Generally: Keep all excavations free from water until:
Formations are covered.
Below ground constructions are completed.
Basement structures and retaining walls are able to resist leakage, water pressure and
flotation.
• Drainage: Form surfaces of excavations and fill to provide adequate falls.
• Removal of water: Provide temporary drains, sumps and pumping as necessary. Do not
pollute watercourses with silt laden water.
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454
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457
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GROUND WATER LEVEL, SPRINGS OR RUNNING WATER
Give notice: If it is considered that the excavations are below the water table.
Springs/ Running water: Give notice immediately if encountered.
PUMPING
General: Do not disturb excavated faces or stability of adjacent ground or structures.
Pumped water: Discharge without flooding the site or adjoining property.
Sumps: Construct clear of excavations. Fill on completion.
Locations: Contractor's choice.
FILLING
500
PROPOSED FILL MATERIALS
Details: Submit full details of proposed fill materials to demonstrate compliance with
specification, including:
Type and source of imported fill.
Proposals for processing and reuse of material excavated on site.
Test reports as required elsewhere.
• Timing: At least 10 days before starting filling.
•
510
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HAZARDOUS, AGGRESSIVE OR UNSTABLE MATERIALS
General: Do not use fill materials which would, either in themselves or in combination with
other materials or ground water, give rise to a health hazard, damage to building structures
or instability in the filling, including material that is:
Frozen or containing ice.
Organic.
Contaminated or noxious.
Susceptible to spontaneous combustion.
Likely to erode or decay and cause voids.
With excessive moisture content, slurry, mud or from marshes or bogs.
Clay of liquid limit exceeding 80 and/or plasticity index exceeding 55.
Unacceptable, class U2 as defined in the Highways Agency 'Specification for highway
works', clause 601.
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FROST SUSCEPTIBILITY
General: Except as allowed below, fill must be non frost-susceptible as defined in
Highways Agency 'Specification for highway works', clause 801.8.
• Test reports: If the following fill materials are proposed, submit a laboratory report
confirming they are non frost-susceptible:
Fine grained soil with a plasticity index less than 20%.
Coarse grained soil or crushed granite with more than 10% retained on a 0.063 mm
sieve.
Crushed chalk.
Crushed limestone fill with average saturation moisture content in excess of 3%.
Burnt colliery shale.
• Frost-susceptible fill: May only be used:
At depths below the finished ground surface greater than 450 mm.
Within the external walls of buildings below spaces that will be heated. Protect from frost
during construction.
Where frost heave will not affect structural elements.
•
525
TESTING OF SUITABILITY OF FILL MATERIALS BEFORE START OF FILLING
Laboratory: UKAS/ NAMAS accredited laboratory.
Submit report to: Structural engineer (two copies).
Timing: 21 days before starting filling.
• Samples: Deliver to laboratory as required.
Additional requirements: none.
• Tests: As directed.
• Frequency: Submit with tender proposed rate and frequency of testing to demonstrate
continuing compliance of imported or reprocessed fill with specified properties.
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530
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610
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618
PLACING FILL
Surfaces of excavations and areas to be filled: Free from loose soil, topsoil, organic
material, rubbish and standing water.
Freezing conditions: Do not place fill on frozen surfaces. Remove material affected by
frost. Replace and recompact if not damaged after thawing.
Adjacent structures, membranes and buried services:
Do not overload, destabilise or damage.
Submit proposals for temporary support necessary to ensure stability during filling.
Allow 14 days (minimum) before backfilling against in situ concrete structures.
Layers: Place so that only one type of material occurs in each layer.
Earthmoving equipment: Vary route to avoid rutting.
COMPACTED FILLING FOR LANDSCAPE AREAS
Fill: Material capable of compaction by light earthmoving plant.
Filling: Layers not more than 200 mm thick. Lightly compact each layer to produce a stable
soil structure.
HIGHWAYS AGENCY TYPE 2 UNBOUND MIXTURE
Fill: To Highways Agency 'Specification for highway works', clauses 801 and 804:
Crushed rock (other than argillaceous rock).
Crushed concrete.
Crushed non-expansive slag to clause 801.2.
Well-burned non-plastic colliery shale.
Natural gravel.
Natural sand.
• Amendments to requirements in Highways Agency 'Specification for highway works': None.
• Filling: To Highways Agency 'Specification for highway works', clause 802.
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700
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710
BACKFILLING AROUND FOUNDATIONS
Under oversite concrete and pavings: Hardcore.
Under grassed or soil areas: Material excavated from the trench, laid and compacted in
300 mm maximum layers.
HARDCORE FILLING
Fill: Granular material, free from excessive dust, well graded, all pieces less than 75 mm in
any direction, minimum 10% fines value of 50 kN when tested in a soaked condition to BS
812-111, and in any one layer only one of the following:
Crushed rock (other than argillaceous rock) or quarry waste with not more binding
material than is required to help hold the stone together.
Crushed concrete, crushed brick or tile, free from plaster, timber and metal.
Crushed non-expansive slag.
Gravel or hoggin with not more clay content than is required to bind the material
together, and with no large lumps of clay.
Well-burned non-plastic colliery shale.
Natural gravel.
Natural sand.
• Filling: Spread and level in 150 mm maximum layers. Thoroughly compact each layer.
•
730
BLINDING
Surfaces to receive sheet overlays or concrete:
Blind with:
Concrete where shown on drawings; or
Sand, fine gravel, or other approved fine material applied to fill interstices. Moisten as
necessary before final rolling to provide a flat, closed, smooth surface.
• Sand for blinding: To BS EN 12620, grade 0/4 or 0/2 (MP).
• Permissible deviations on surface level: +0 -25 mm.
•
HIGHWAYS AGENCY EARTHWORKS SPECIFICATION APPENDICES
900
APPENDIX 6/1 - REQUIREMENTS FOR ACCEPTABILITY AND TESTING, ETC. OF
EARTHWORKS MATERIALS
•
.
905
APPENDIX 6/2 - REQUIREMENTS FOR DEALING WITH CLASS U1B AND U2
UNACCEPTABLE MATERIAL
•
.
910
APPENDIX 6/3 - REQUIREMENTS FOR EXCAVATION, DEPOSITION, COMPACTION
(OTHER THAN DYNAMIC COMPACTION)
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.
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915
APPENDIX 6/4 - REQUIREMENTS FOR CLASS 3 MATERIAL
925
APPENDIX 6/6 - FILL TO STRUCTURES AND FILL ABOVE STRUCTURAL
FOUNDATIONS
•
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930
APPENDIX 6/7 - SUB-FORMATION AND CAPPING AND PREPARATION AND
SURFACE TREATMENT OF FORMATION
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.
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E
In situ concrete/Large precast concrete
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E05
In situ concrete construction generally
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E05 In situ concrete construction generally
220
STRUCTURAL DESIGN PROVIDED
Description: Foundations, ground floor slab and structural topping to upper floors.
Requirements:
Generally: As section B50.
Additional requirements: None.
• Production/ execution records: In accordance with the designated code of practice and the
latest edition of the National Structural Concrete Specification. Records to include date and
time of pour, concrete batch plant used, temperature records, inspections/QA and
photographic records).
•
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223
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225
STRUCTURAL DRAWINGS AND SCHEDULES
Standards:
Drawings: To 'Standard method of detailing structural concrete' published by the
Institution of Structural Engineers.
Reinforcement schedules: To BS 8666.
TEMPERATURE RECORDS
Requirement: Throughout period of concrete construction record:
Daily: Maximum and minimum atmospheric shade temperatures.
Under adverse temperature conditions: Temperature at commencement and end of
placing.
• Equipment: Submit proposals.
Location: In the shade, close to the structure.
•
235
OPENINGS, INSERTS AND FIXINGS
Requirement: Collate all information.
Submit: Details where openings, inserts and fixings can only be accommodated by
adjustments to reinforcement.
• Locate reinforcement: To ensure specified minimum cover at openings and inserts and to
be clear of fixing positions.
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290
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300
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310
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ACCURACY OF CONSTRUCTION
Setting out: To BS 5964-1.
Geometrical tolerances: To Section 7 of the 'National Structural Concrete Specification for
Building Construction'.
Conflicts: Notwithstanding tolerances specified elsewhere, do not exceed requirements
for compliance with the designated code of practice.
Substitution of alternative requirements: Verticality of lift shaft at any point to be within
20mm,.
LEVELS OF STRUCTURAL CONCRETE FLOORS
Tolerances (maximum):
Level of floor: ±10mm.
Steps in floor level: ±5 mm.
SURFACE REGULARITY OF CONCRETE FLOORS TO BS 8204 - GENERAL
Standard: To BS 8204-1 or -2.
Measurement: From underside of a 2 m straightedge (between points of contact) placed
anywhere on surface and using a slip gauge.
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SURFACE REGULARITY OF CONCRETE FLOORS TO BS 8204 - TOLERANCE CLASS S
R2
• Location: All flat slabs.
• Abrupt changes: Not permitted (i.e. no ridges/steps permitted).
410
•
IN SITU CONCRETE CONSTRUCTION - SUPERVISION/ CHECKING
Standard: To BS EN 13670, Execution Class 2.
•
•
•
WATER RESISTANT CONCRETE CONSTRUCTION
Description: Lift pit.
Form of construction: To BS 8102, Type B.
Requirement: Work is to be water resistant when tested to clause E05/ 450.
420
450
INSPECTION OF WATER EXCLUDING STRUCTURES
Notification: Give not less than seven days warning before inspection.
First inspection:
Purpose: To identify any defects which may lead to water penetration or damp patches.
Timing: As soon as possible after completion of the work and before backfilling.
• Final inspection:
Purpose: To identify any points of water penetration or damp patches.
Timing: After backfilling, when the ground water table has returned to normal level.
• Requirement: Exposed faces of the structure must show no signs of leakage and remain
apparently dry.
•
•
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E10
Mixing/casting/curing in situ concrete
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E10 Mixing/casting/curing in situ concrete
CONCRETE
101
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105
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107
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SPECIFICATION
Concrete generally: To BS 8500-2.
Exchange of information: Provide concrete producer with information required by BS 85001, clauses 4 and 5.
DESIGNATED CONCRETETo all concrete unless noted otherwise
Designation: RC32/40.
Fibres: Not required.
Aggregates:
Size (maximum): 20 mm.
Coarse recycled aggregates: Permitted at a mass fraction not exceeding 25% of coarse
aggregate.
Additional aggregate requirements: None.
Special requirements for cement/ combinations: To comply with table A.11 of BS 8500-1
for class DC-1 with respect to maximum water cement ratio, min cement content and
cement combinations.
Consistence class: S3.
Chloride class: Cl 0.40 (except those using SRPC use Cl 0.20) .
Admixtures: Concrete producer's choice.
Additional mix requirements: None.
DESIGNATED CONCRETETo strip footings
Designation: GEN1.
Fibres: Not required.
Aggregates:
Size (maximum): 20 mm.
Coarse recycled aggregates: Not permitted.
Additional aggregate requirements: None.
Special requirements for cement/ combinations: None.
Consistence class: S3.
Chloride class: Cl 0.40.
Admixtures: Concrete producer's choice.
Additional mix requirements: None.
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111
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DESIGNATED CONCRETETo lift pits
Designation: RC32/40.
Fibres: Not required.
Aggregates:
Size (maximum): 20 mm.
Coarse recycled aggregates: Not permitted.
Additional aggregate requirements: None.
Special requirements for cement/ combinations: To comply with table A.11 of BS 8500-1
for class DC-1 with respect to maximum water cement ratio, min cement content and
cement combinations.
Consistence class: S3.
Chloride class: Cl 0.40 (except those using SRPC use Cl 0.20) .
Admixtures: Proprietary waterproof additive.
Additional mix requirements: Mix design to incorporate waterproof additive used strictly in
accordance with manufacturer's recommendations. Quality control measures to be in place
to ensure detailed drawing, admixture dosing, pre-pour checks, concrete placement are all
in line with manufacturer's recommendations. Proposals to be agreed with design team.
MATERIALS, BATCHING AND MIXING
215
READY-MIXED CONCRETE
Production plant: Currently certified by a body accredited by UKAS to BS EN 45011 for
product conformity certification of ready-mixed concrete .
• Source of ready-mixed concrete: Obtain from one source if possible . Otherwise, submit
proposals .
Name and address of depot: Submit before any concrete is delivered .
Delivery notes: Retain for inspection .
• Declarations of nonconformity from concrete producer: Notify immediately .
•
221
•
225
•
230
INFORMATION ABOUT PROPOSED CONCRETES
Submit when requested:
Details listed in BS 8500-1, clause 5.2.
Additional information: Data for anticipated strength gain.
CHANGES TO SPECIFICATION
Changes to specification of fresh concrete (outside concrete producer's responsibility):
Prohibited.
INTERRUPTION OF SUPPLY DURING CONCRETING
Elements without joints: Where elements are detailed to be cast in a single pour without
joints, make prior arrangements for a back-up supply of concrete.
• Elsewhere:
Preparation: Manage pour to have a full face, and have materials available to form an
emergency construction joint while concrete can still be worked.
Before pour is completed: Submit location and details of joint, make proposals for joint
preparation.
•
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310
•
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•
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315
RECYCLED AGGREGATE
Standard: To BS 8500-2, clause 4.3 and BS EN 12620.
Type: contractor to submit proposals.
Source: from local supplier.
Quality control: Waste and Resources Action Programme (WRAP) Quality protocol for the
production of aggregates from inert waste. Revised edition September 2005.
Limitations on use:
- Concrete strength class (maximum): RC40.
- Permitted exposure classes: X0, XC1, XC2, XC3, XC4, XF1, DC-1.
Additional restrictions on content:
- Acid-soluble sulfate content (maximum): to be agreed.
- Alkali-aggregate reactivity: Do not use aggregate containing reactive silica.
Test method:
- Determination of chloride content: To BS EN 1744-5.
- Determination of alkali content: Not applicable.
Frequency of testing: to be agreed.
Other requirements: none.
AGGREGATES FOR EXPOSED VISUAL CONCRETE
Limitations on contaminants: Free from absorbent particles which may cause 'popouts',
and other particles such as coal and iron sulfide which may be unsightly or cause
unacceptable staining .
• Colour: Consistent .
• Supply: From a single source and maintained throughout the contract .
• Samples: Submit on request .
•
325
•
MATERIALS FOR EXPOSED VISUAL CONCRETE
Alterations to sources, types and proportions: Submit proposals.
•
ADMIXTURES
Calcium chloride and admixtures containing calcium chloride: Do not use.
415
490
•
PROPERTIES OF FRESH CONCRETE
Adjustments to suit construction process: Determine with concrete producer. Maintain
conformity to the specification.
PROJECT TESTING/ CERTIFICATION
505
PROJECT TESTING OF CONCRETE - GENERAL
Testing: To BS 8500-1, Annex B.
Nonconformity: Obtain instructions immediately.
• Recording: Maintain complete correlated records including:
Concrete designation.
Sampling, site tests, and identification numbers of specimens tested in the laboratory.
Location of the parts of the structure represented by each sample.
Location in the structure of the batch from which each sample is taken.
•
508
REGULAR PROJECT TESTING OF CONCRETE
Tests: Compressive strength.
Sampling:
Point: At point of discharge from delivery truck.
Rate: min one sample for every 30 m³ for early age compressive strength testing prior to
striking slab formwork.
• Other requirements: Cubes for early age strength testing to be stored under same
conditions as concrete in members.
•
•
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520
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530
TESTING LABORATORY
Laboratory: Accredited by UKAS or other national equivalent.
Name and UKAS reference number: Submit well in advance of making trial mixes or
concrete for use in the works.
TESTS RESULTS
Submission of reports: Within one day of completion of each test.
Number of copies: 1 by e-mail.
• Reports on site: A complete set, available for inspection.
•
550
BROKEN CUBES FROM FAILED STRENGTH TESTS
Nonconformity: Keep separately the pieces of each cube which fail to meet the conformity
requirements for individual results.
• Period for keeping cubes: Obtain instructions.
•
PLACING/ COMPACTING/ CURING AND PROTECTING
610
•
630
•
640
•
•
648
CONSTRUCTION/ SEQUENCE/ TIMING REQUIREMENTS
Flat slabs require two levels of backprops. Backprops to be in place before loading out
with formwork or other materials. Supporting slabs must attain a minimum compressive
(cube) strength of 35 N/mm² prior to pouring the slab over. Higher strength concrete may
be used to achieve such strengths prior to 28 days if required.
Backprops should be positioned on a grid of approximately 2.0m x 2.0m, and the ends of
cantilevers. Backprops should be hand tight (do not over tighten).
Ensure that when backpropping (or propping formwork) to ground level that the ground
comprises a granular sub-base and is sufficiently compacted and level. Spreaders should
be used on the ground with a minimum size of 600x600mm (subject to confirmation of
loadings).
Check soffit levels of formwork during the pouring of the first floor slab ensure levels are
maintained .
PREMATURE WATER LOSS
Requirement: Prevent water loss from concrete laid on absorbent substrates.
Underlay: Select from:
Polyethylene sheet: 250 micrometres thick.
Building paper: To BS 1521, grade B1F.
Installation: Lap edges 150 mm.
CONSTRUCTION JOINTS
Location of joints: Contractor to submit proposals - locate at quarter point between columns.
Preparation of joint surfaces: Remove surface laitance and expose aggregate by lightly
brushing and spraying. Joint surface to be clean and damp immediately before placing
fresh concrete.
•
ADVERSE TEMPERATURE CONDITIONS
Requirement: Submit proposals for protecting concrete when predicted ambient
temperatures indicate risk of concrete freezing or overheating.
•
SURFACES TO RECEIVE CONCRETE
Cleanliness of surfaces immediately before placing concrete: Clean with no debris, tying
wire clippings, fastenings or free water.
650
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660
INSPECTION OF SURFACES
Notice: Give notice to allow inspections of reinforcement and surfaces before each pour of
concrete.
Period of notice: Obtain instructions.
• Timing of inspections: When fixing of reinforcement is complete.
•
670
TRANSPORTING
General: Avoid contamination, segregation, loss of ingredients, excessive evaporation and
loss of workability. Protect from heavy rain.
• Entrained air: Anticipate effects of transport and placing methods in order to achieve
specified air content.
•
680
•
•
•
•
•
•
•
690
PLACING
Records: Maintain for time, date and location of all pours.
Timing: Place as soon as practicable after mixing and while sufficiently plastic for full
compaction.
Temperature limitations for concrete: 30°C (maximum) and 5°C (minimum), unless
otherwise specified. Do not place against frozen or frost covered surfaces.
Continuity of pours: Place in final position in one continuous operation up to construction
joints. Avoid formation of cold joints.
Discharging concrete: Prevent uneven dispersal, segregation or loss of ingredients or any
adverse effect on the formwork or formed finishes.
Thickness of layers: To suit methods of compaction and achieve efficient amalgamation
during compaction.
Poker vibrators: Do not use to make concrete flow horizontally into position, except where
necessary to achieve full compaction under void formers and cast-in accessories and at
vertical joints.
COMPACTING
General: Fully compact concrete to full depth to remove entrapped air. Continue until air
bubbles cease to appear on the top surface.
Areas for particular attention: Around reinforcement, under void formers, cast-in
accessories, into corners of formwork and at joints.
• Consecutive batches of concrete: Amalgamate without damaging adjacent partly hardened
concrete.
• Methods of compaction: To suit consistence class and use of concrete.
•
720
VIBRATORS
General: Maintain sufficient numbers and types of vibrator to suit pouring rate, consistency
and location of concrete.
• External vibrators: Obtain approval for use.
•
730
PLASTIC SETTLEMENT
Settlement cracking: Inspect fresh concrete closely and continuously wherever cracking is
likely to occur, including the top of deep sections and at significant changes in the depth of
concrete sections.
Timing: During the first few hours after placing and whilst concrete is still capable of
being fluidized by the vibrator .
• Removal of cracks: Re-vibrate concrete.
•
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810
CURING GENERALLY
Requirement: Keep surface layers of concrete moist throughout curing period, including
perimeters and abutments, by either restricting evaporation or continuously wetting
surfaces of concrete.
Surfaces covered by formwork: Retain formwork in position and, where necessary to
satisfy curing period, cover surfaces immediately after striking.
Top surfaces: Cover immediately after placing and compacting. If covering is removed
for finishing operations, replace it immediately afterwards.
• Surface temperature: Maintain above 5°C throughout the specified curing period or four
days, whichever is longer.
• Records: Maintain details of location and timing of casting of individual batches, removal of
formwork and removal of coverings. Keep records on site, available for inspection.
•
811
COVERINGS FOR CURING
Sheet coverings: Suitable impervious material .
Curing compounds: Selection criteria:
Curing efficiency: Not less than 75% or for surfaces exposed to abrasion 90%.
Colouring: Fugitive dye.
Application to concrete exposed in the finished work: Readily removable without
disfiguring the surface.
Application to concrete to receive bonded construction/ finish: No impediment to
subsequent bonding.
• Interim covering to top surfaces of concrete: Until surfaces are in a suitable state to receive
coverings in direct contact, cover with impervious sheeting held clear of the surface and
sealed against draughts at perimeters and junctions.
•
•
812
•
PREVENTING EARLY AGE THERMAL CRACKING
Deep lifts or large volume pours: Submit proposals for curing to prevent early age thermal
cracking, taking account of:
Temperature differentials across sections.
Coefficient of thermal expansion of the concrete.
Strain capacity of the concrete mix (aggregate dependent).
Restraint.
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820
•
•
•
•
•
840
•
CURING PERIODSALL CONCRETE WORKS
General: Curing periods are in days (minimum).
Definition of 't': The average surface temperature of concrete in degrees Celsius during
the curing period.
Curing periods for concrete made using CEM1 strength class 42.5 or 52.5, or SRPC class
42.5:
Drying winds or dry, sunny weather (relative humidity < 50%): 80/(t+10) when surface
temperature is between 10°C and 25°C.
Intermediate conditions (relative humidity between 50 and 80%): 60/(t+10) when surface
temperature is between 10°C and 25°C.
Damp weather, protected from sun and wind (relative humidity > 80%): No special
requirements.
Curing periods for concrete made using cements listed in BS8500-1, table A.6 except for
those listed above and for supersulfated cement:
Drying winds or dry, sunny weather (relative humidity < 50%): 140/(t+10) when surface
temperature is between 10°C and 25°C.
Intermediate conditions (relative humidity between 50 and 80%): 80/(t+10) when surface
temperature is between 10°C and 25°C.
Damp weather, protected from sun and wind (relative humidity > 80%): No special
requirements.
Curing periods: For concretes using admixtures or other types of cements/ combinations:
Submit proposals.
Other requirements: Seek instructions where surface temperature of concrete is likely to be
less than 5°C.
PROTECTION
Prevent damage to concrete, including:
Surfaces generally: From rain, indentation and other physical damage.
Surfaces to exposed visual concrete: From dirt, staining, rust marks and other
disfiguration.
Immature concrete: From thermal shock, physical shock, overloading, movement and
vibration.
In cold weather: From entrapment and freezing expansion of water in pockets, etc. . .
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Formwork for in situ concrete
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E20 Formwork for in situ concrete
GENERALLY/ PREPARATION
110
•
120
•
132A
•
145
•
170
•
LOADINGS
Requirement: Design and construct formwork to withstand the worst combination of the
following:
Total weight of formwork, reinforcement and concrete.
Construction loads including dynamic effects of placing, compacting and construction
traffic.
Wind and snow loads.
FORMWORK DETAILS
Provide the following: Construction joints - positions and types.
PROPPING
General: Prevent deflection and damage to the structure. Carry down props to bearings
strong enough to provide adequate support throughout concreting operations. To slabs
provide two levels of back props. Backprops to be on a grid of 2.0m x 2.0m (see also
section E10). Backprops to be in place prior to loading out slabs with materials or
formwork. Slabs immediately beneath the one being poured to have achieved a min cube
strength of 35 N/mm² prior to pouring.
Method statement: Submit proposals for prop bearings and sequence of propping/
repropping and backpropping.
Timing of submission: Submit prior to erection of formwork / backprops - allow 3 working
days for approval .
PERMANENT FORMWORK
Location and materials: Submit proposals.
WORK BELOW GROUNDFOUNDATIONS
Casting vertical faces against faces of excavation: Permitted.
Requirements: Increase nominal cover to reinforcement to 75 mm and Prevent
contamination of concrete by loose soil.
CONSTRUCTION
310
ACCURACY
General requirement for formwork: Accurately and robustly constructed to produce finished
concrete in the required positions and to the required dimensions.
• Formed surfaces: Free from twist and bow (other than any required cambers).
• Intersections, lines and angles: Square, plumb and true.
•
315
SUBSTRUCTURE FORMWORK AND UNDERSLAB INSULATION
Cutting: Neat and accurate to edges, and around penetrations and downstands.
Laying: Tightly butted and fully supported on firm, even substrate.
Vertical faces: Stiffen as necessary to act as shutter.
Formwork/ insulation surfaces: Protect from indentation by spacers and other items.
Joints in formwork/ insulation and with edge structure and penetrations: Seal to prevent
penetration of concrete.
• Concrete placement: Restrain formwork/ insulation against movement.
•
•
•
•
•
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320
•
330
JOINTS IN FORMS
Requirements including joints in form linings and between forms and completed work:
Prevent loss of grout, using seals where necessary.
Prevent formation of steps. Secure formwork tight against adjacent concrete.
INSERTS, HOLES AND CHASES
Positions and details:
Dimensioned on drawings provided on behalf of the Employer: Do not change without
consent.
Un-dimensioned or from other sources: Submit proposals.
• Positioning relative to reinforcement: Give notice of any conflicts well in advance of placing
concrete.
• Method of forming: Fix inserts or box out as required. Do not cut hardened concrete
without approval.
•
340
•
350
•
FORM TIES
Metal associated with form ties/ devices: Prohibited within cover to reinforcement.
Compatible with reinforcement metal.
•
PROHIBITION OF FORM TIES
Do not use ties in the following work: Avoid to lift pit walls (i.e. below ground level) or
submit proposals to ensure seal against water ingress) .
351
470
KICKERS
Method statement: Submit proposals including means of achieving quality of concrete
consistent with that specified for the column or wall.
Kicker height: 100 mm to 150 mm.
RELEASE AGENTS
Use: All formwork.
General: Achieve a clean release of forms without disfiguring the concrete surface.
Product types: Compatible with formwork materials, specified formed finishes and
subsequent applied finishes. Use the same product throughout the entire area of any one
finish.
• Protection: Prevent contact with reinforcement, hardened concrete, other materials not part
of the form face, and permanent forms.
•
•
•
480
•
•
SURFACE RETARDERS
Use: Obtain approval.
Reinforcement: Prevent contact with retarder.
STRIKING
510
•
521
STRIKING FORMWORK
Timing: Prevent any disturbance, damage or overloading of the permanent structure.
MINIMUM PERIOD FOR RETAINING FORMWORK/ TEMPORARY SUPPORTS IN
POSITION
• Concrete strength at time of formwork removal (minimum): 10 N/mm² cube strength for
columns and walls, 21 N/mm² for slabs.
• Assumptions: Imposed load will not exceed 0.75 kN/m² until concrete reaches full maturity.
Before removing formwork: Submit proposals if assumptions will not be realised.
• Method to be used in assessing early age strength of concrete: Floor slabs (considering
last section of slab cast in the day) - LOK test to recommendations in BCA best practice
guide 97.503 and Temperature matched curing (TMC) of cube samples to BS 1881-130.
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FORMED FINISHES
610
BASIC FINISH
Requirements: Face fully compacted and to tolerance, otherwise no particular
requirements.
• Use: Faces below ground level.
•
620A
•
•
•
•
•
635A
•
•
•
750
•
PLAIN SMOOTH FINISH
Location: Retaining walls, structural topping
Finish: Even with panels arranged in a regular pattern as a feature of the surface.
Permissible deviation of surfaces:
Sudden irregularities (maximum): 5 mm.
Gradual irregularities when measured from the underside of a 1 m straightedge, placed
anywhere on surface (maximum): 5 mm.
Variations in colour:
Permitted: Those caused by impermeable form linings.
Not permitted: Discoloration caused by contamination or grout leakage.
Surface blemishes:
Permitted: Blowholes less than 10 mm in diameter and at an agreed frequency.
Not permitted: Voids, honeycombing, segregation and other large defects.
Formwork tie holes: In a regular pattern and filled with matching mortar.
STANDARD FINISH Fairfaced exposed RC retaining walls
Standard: BS 8110-1, clause 6.2.7.3.
Quality: Type B.
Face as formed: As the regional Reference Panel.
ARRISES, MARGINS AND JUNCTIONS
Requirements:
Retaining walls exposed at ground floor level to have 25x25 chamfers.
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E30
Reinforcement for in situ concrete
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E30 Reinforcement for in situ concrete
REINFORCEMENT
110
QUALITY ASSURANCE OF REINFORCEMENT
Standards:
Reinforcement: To BS 4449, BS 4482, BS 4483 or BS 6744.
Cutting and bending: To BS 8666.
• Source of reinforcement: Companies holding valid certificates of approval for product
conformity issued by the UK Certification Authority for Reinforcing Steels (CARES).
•
150A
•
210
•
•
255
•
RIBBED BAR REINFORCEMENT
Standard: To BS 4449 / BS EN 1992-2-1.
Strength grade: B500B.
STANDARD FABRIC REINFORCEMENT
Standard: To BS 4483.
Strength grade: B500B.
PREFABRICATED CONTINUITY REINFORCEMENT STRIPS
Source: Obtain from a manufacturer holding a valid Technical Product Approval certificate
issued by the UK Certification Authority for Reinforcing Steels (CARES) or equivalent.
WORKMANSHIP
310
•
•
320
•
•
410
•
451
CUTTING AND BENDING REINFORCEMENT
General: To schedules and to BS 8666.
Bending on site, including minor adjustments: Obtain instructions.
PROTECTION OF REINFORCEMENT
Dropping from height, mechanical damage and shock loading: Prevent.
Cleanliness of reinforcement at time of pouring concrete: Free from corrosive pitting, loose
millscale, loose rust and contaminants which may adversely affect the reinforcement,
concrete, or bond between the two.
LAPS OR SPLICES
Details not shown on drawings: Obtain instructions.
FIXING REINFORCEMENT
Standard: To BS 7973-1 and -2.
Installation: In addition to any spacers and chairs shown on drawings or schedules, provide
adequate support, tie securely and maintain the specified cover.
• Tying:
Wire type: 16 gauge black annealed. Use stainless steel wire for stainless steel
reinforcement.
Ends of tying wire: Prevent intrusion into the concrete cover. Remove loose ends.
• Compatibility of metals: Prevent contact between ordinary carbon steel and stainless or
galvanized reinforcement.
•
•
470
•
•
TOLERANCES ON COVER
Tolerance (maximum): 5 mm reduction in cover, 10 mm increase in cover .
Checking specified cover dimensions: Before concreting check that cover dimensions will
be achieved.
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510
•
521
RUST STAINING
Staining of surfaces of concrete which will be exposed to view in the finished work:
Prevent.
COVER METER FOR USE BY OTHERS
Type of cover meter: Provide a magnetic induction digital display type selected to suit
arrangement and type of reinforcement.
• Availability: Calibrate and maintain ready for use by others as instructed.
Periods/ time: When requested by engineer or main contractor to check works.
•
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E40
Designed joints in in situ concrete
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E40 Designed joints in in situ concrete
120
CONSTRUCTION/ MOVEMENT JOINTS GENERALLY
Accuracy: Position and form joints accurately, straight, well-aligned and truly vertical or
horizontal or parallel with setting out lines of the building.
• Modifications to joint design or location: Submit proposals.
• Placing concrete to form movement joints:
Maintain effectiveness of joints. Prevent concrete entering joints or penetrating or
impregnating compressible joint fillers.
Do not place concrete simultaneously on both sides of movement joints.
•
132
ADDITIONAL CONSTRUCTION JOINTS
Joints additional to those required by designer:
In slabs only at quarter spans, providing adjacent spans continuously supported until
complete slab poured .
• Approval of additional joints: Submit proposals.
•
230
PREPARATION OF CONSTRUCTION JOINTS
Roughening of joint surfaces: Select from:
Brushing and spraying: Remove surface laitance and expose aggregate finish while
concrete is still green.
Other methods: Submit proposals.
• Condition of joint surfaces immediately before placing fresh concrete: Clean and damp.
•
320
•
•
•
•
•
HYDROPHILIC WATERSTOPS
Manufacturer: Submit proposals.
Product reference: Submit proposals.
Location: To lift pit kicker/ internal / construction joints.
Method of fixing: As recommended by manufacturer.
Condition of concrete surface at time of fixing: Clean and free from ponded or running
water.
Protection: Prevent wetting of exposed sections of waterstop.
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E41
Worked finishes to in situ concrete
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E41 Worked finishes to in situ concrete
150
•
•
320A
•
FINISHING
Timing: Carry out at optimum times in relation to setting and hardening of concrete.
Prohibited treatments to concrete surfaces:
Wetting to assist surface working.
Sprinkling cement.
TROWELLED FINISH All slabs . structural toppings
Surface on completion: Uniform, smooth but not polished, free from trowel marks and
blemishes, free from ridges and steps, and suitable to receive specified flooring material
(check with flooring manufacturer prior to commencing works).
335A
DRY SHAKE TROWELLED FINISH FOR WEARING SURFACES To ground floor plant
room
• Manufacturer: Sika Limited.
Web: www.sika.co.uk.
Email: enquiries@uk.sika.com.
Product reference: Sikafloor® – 1 MetalTop Metallic Dry Shake Floor Hardener
• Sealer: Proseal
• Colour: to architect details.
410
POWER GROUND FINISH FOR WEARING SURFACES
Grinding: Remove 1-2 mm from surface.
Timing: When concrete is sufficiently hard for fine aggregate surface particles not to be
dislodged.
• Cleaning: Remove dust and wash down.
• Surface on completion: Even glass-paper texture, free from blemishes and trowel marks.
•
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E60
Precast/ composite concrete floors/ roof decks
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E60 Precast/ composite concrete floors/ roof decks
PROPRIETARY FLOORS/ ROOF DECKS
180
PRECAST STAIRSInternal
Manufacturer: As precast floors.
Product reference: Contractor's choice.
• Parameters: For dimensions refer to architects drawings.
• Finish:
Exposed faces: Manufacturer's standard.
Treads and risers: Manufacturer's standard.
• Other requirements: Contractors design & detail to tie back to primary steel frame.
•
PERFORMANCE SPECIFIED FLOORS/ ROOF DECKS
210A
•
•
•
•
•
•
•
•
•
211A
•
•
•
•
•
•
•
•
•
FLOOR NORTH AND CENTRAL WINGS - PRECAST SLAB FOR L1 - ROOF
Type of construction: Hollow Core.
Overall depth (excluding finishes): 150 mm.
Span: 5.0m max.
Self weight: Maximum 2.4 kN/m².
In situ continuity reinforcement: NA.
Void formers: N.A..
In situ concrete topping to composite construction: 75mm reinforced structural topping.
Finish to soffit: Manufacturers standard, to be approved by architect for exposed soffit.
Other requirements: Allow for service penetrations as indicated on services drawings. Cut
around columns and posts within SFS zone. Local break outs for continuity reinforcement
and balustrade fixings. Chamfer ends to facilitate installation on steel bearing angles.
Contractors design and detail..
FLOOR SOUT WING PRECAST SLAB FOR L1 - ROOF
Type of construction: Hollow Core.
Overall depth (excluding finishes): 200mm to L1 and L2, 250mm to roof.
Span: 7.5m max.
Self weight: Maximum 3.0 and 3.3 kN/m².
In situ continuity reinforcement: NA. .
Void formers: N.A..
In situ concrete topping to composite construction: 75mm reinforced structural topping.
Finish to soffit: Manufacturers standard, exposed soffit to be approved by architect.
Other requirements: Allow for service penetrations as indicated on drawings. Cut around
columns and posts in SFS zone. Contractors design and detail.
GENERAL/ PERFORMANCE
240
DETAILING OF PROPRIETARY SYSTEM
Installation details: Submit location and assembly drawings showing every aspect of the
construction, incorporated components and features, trimming for voids, holes for services,
and related work by others.
Purpose: To allow checking of compatibility with surrounding structure and coordination
of services.
• Method statement and risk assessment for installation: Submit.
• Programme: Submit well in advance of construction.
•
250
CONTRACTOR'S STRUCTURAL DESIGN
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•
252
•
Design: Complete in accordance with the designated code of practice to satisfy specified
performance criteria..
Composite construction: N.A..
Fully precast construction: See SPEC 01 dwg for loading requirements.
FIRE ALL PRECAST
60 mins fire resistance REI.
INSTALLATION
320
CONCRETE INFILL
Designated concrete: To BS 8500-2.
Designation: RC25/30.
Aggregate size (maximum): 10 mm generally but 5 mm in shear keys between precast
units.
• Preparation: Thoroughly clean and wet surfaces of precast units.
• Placing: Avoid segregation and compact thoroughly to eliminate voids.
Extent: Fill troughs and other holes.
Finish: Flush with top of precast units.
• Protection: Prevent movement of units until concrete has gained sufficient strength.
•
350A
•
LEVELS OF STRUCTURAL CONCRETE FLOORS
Tolerances: +/-10mm at bearing. 10mm max level difference across adjacent units.B
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G
Structural/Carcassing metal/timber
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G10
Structural steel framing
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G10 Structural steel framing
To be read with Preliminaries/ General conditions.
GENERAL REQUIREMENTS/ INFORMATION
105
SCOPE OF WORK / GENERAL
Scope of works: The detailing, fabrication, protection systems and erection of all steelwork
shown on structural general arrangement and detail drawings.
• The structure is a two- and three storey simple steel frame structure with vertically braced
bays. Other various ancillary primary and secondary hot rolled steel elements include: such
posts to support the brise soleil strips and high plant screens posts and angles.
• Comply with the requirements of the latest edition of the National Structural Steelwork
Specification (NSSS).
•
115
•
•
•
•
•
116
DESIGN CONSTRAINTS - GENERAL
Members forming bracing systems or girders of lattice construction: Unless detailed or
instructed otherwise, position so that their lines of action intersect at a point.
Bolts/ Screws:
Diameter (minimum): 16 mm unless noted otherwise on drawings.
Number per connection (minimum): Two, unless otherwise indicated.
Other requirements: All bolts grade 8.8, hot dip galvanised uno. Chose bolt dimensions
to ensure that threads do not occur in shear plane of joint.
Punching of bolt holes: Permitted except in: preloaded joints (hsfg bolts), galvanised
steelwork, joints under fatigue/cyclic loading, edge distances less than specified in BS EN
1993 and NA where applicable).
Welds: At least 6 mm fillet. Where full profile welds cannot be used, single sided fillet welds
are not permitted - use full penetration butt welds.
Other constraints: Comply with BS EN 1993, BS5950:2000 and SCI/BCSA Joints in Steel
Construction (Green Books) and Cidect/Corus guides for SHS welded connections. For
beam connections with notched top and bottom flanges use double angle web cleats
(rather than fin plates or flexible end plates). Where connection details are shown on
drawings - comply with these requirements or submit alternative proposals prior to
fabrication - in all cases the fabricator is to satisfy itself that the design forces can be
resisted. Submit calculations for all non-standard (non-Green Book) connections prior to
fabrication.
DESIGN CONSTRAINTS - STEELWORK TO BE GALVANIZED
Steel grades: Do not use steel downgraded from a higher specification.
Detail design: Avoid details that will increase the risk of initiating liquid metal assisted
cracking (LMAC).
Particular restrictions: Where possible use bolted connections and balance primary
welds. Follow guidance from Galvanisers Association. Distortions to remain within the
NSSS tolerances.
• Other requirements:
- Drill holes for bolts;
- Grind exposed cut edges and notches;
- Seal vent and drainage holes in hollow sections using non-ferrous plugs;
- All radiused edges in changes of section (e.g. notches) to be 20mm.
•
•
120
•
DRAWINGS AND CALCULATIONS
Requirement: Before preparing detailed fabrication drawings, submit:
General arrangement drawings with individual steel members clearly identified.
Calculations for major connections.
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121
•
•
•
•
•
•
•
125
•
125A
•
130
DRAWING SUBMISSION PROCEDURE
The contractor is to prepare and submit general arrangement drawings and complete
connection details (including plate thickness/size, steel grades, bolt diameters and grades,
bolt centre/edge distances, weld type/size/lengths) along with calculations for nonstandard/major connections (incl. all moment connections) at least two weeks prior to
starting fabrication.
Submit 1 full size paper copy by post + pdf copy by e-mail.
Allow 10 working days for review.
Allow 10 working days for each subsequent review.
Approval shall not in anyway relieve the contractor of his responsibility for any errors which
his drawings or calculations may contain. Unless specifically indicated contrary on returned
drawings, all works shall comply with the contract documents.
Review categories: Category A - fabrication and construction may proceed in accordance
with the submitted drawings. Category B - fabrication and construction may proceed in
accordance with the submitted drawings subject to the steel contractor taking the
necessary action based on the engineer's comments/notations on the returned drawings.
The steel contractor shall submit amended documents to the engineer as soon as possible
until such documents have received status A. Category C - fabrication and construction
may not proceed on the elements of works included or effected by the returned drawings.
Documents shall be re-submitted until such documents have achieved status A.
The granting of category A status will be conditional on receipt of all necessary
calculations, certification, samples etc, as required by the specification, Notwithstanding
the engineer's comments, the detailed design carried out be the contractor, materials,
fabrication and construction will remain the responsibility of the steel contractor.
SPECIFICATION STANDARD
Standard: Comply with latest edition of National Structural Steelwork Specification (NSSS).
Additional requirements: None.
Document availability: For the duration of the work, at fabrication shop and on site.
SPECIFICATION STANDARD
Standard: Comply with latest edition of National Structural Steelwork Specification
(NSSS) / BS EN 1090-2.
Additional requirements: None.
Document availability: For the duration of the work, at fabrication shop and on site.
GENERAL STEEL SECTIONS AND PLATES For all UB, UC, PFC, angle, tee and plate
Standard: To BS EN 10025-2.
Grade: Subject to availability: S355J0.
Options: None.
• Source: Obtain steel from a source accredited to a national or internationally accepted
quality standard.
• Other requirements: Steel to be galvanized to have a carbon equivalent value not
exceeding 0.44.
•
•
135
HOLLOW STEEL SECTIONS All hollow sections
Standard: To BS EN 10210-1.
Grade: S355J0H or S355J2H.
Options: None.
• Source: Obtain steel from a source accredited to a national or internationally accepted
quality standard.
• Other requirements: Steel to be galvanized to have a carbon equivalent value not
exceeding 0.44.
•
•
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140
•
SITE DIMENSIONS
All dimensions between new and existing structure are to be measured and checked by
the steel contractor on site for position and level prior to fabrication or as necessary to
progress design and production of fabrication drawings. (Existing structures include any
structure on site, whether new or existing, which may influence the dimension of a piece of
steelwork). Prior to the production of fabrication drawings, check existing steel section
sizes to which new steel is connected. Submit copies of this information to the engineer
and report any discrepancies with immediate effect. The cost of this survey work is to be
borne by the steel contractor.
FRAME SYSTEMS
170
COLD-FORMED GALVANIZED STEELPosts to parapet
Manufacturer: Contractor's choice.
Product reference: Contractors choice.
• Material: Galvanized steel sheet to BS EN 10326.
Thickness: min 0.9mm but contractors design.
Designation: 450N/mm² yield strength, G275 coating.
•
FABRICATION
180
•
181
NOTIFICATION OF COMMENCEMENT
Give notice: Before fabrication is due to start.
Period of notice (minimum): Five working days.
GENERAL
Ensure fabrication processes do not cause changes in material properties resulting in noncomformance with specified requirements.
• Fabrication tolerances in accordance with NSSS and BS5950:2 section 7.2 except:
member length +0mm or -3mm, holes 2mm larger than bolt diameter, close tolerance bolts
only for shop assembly, special measures for tolerances (e.g. slotted holes, turnbuckles,
shims) only to engineers written approval.
• Steel sections to be to British manufacture unless otherwise agreed with approved test
certification, free from detrimental corrosion and free from lamination to BS5996.
• Welds for S355 material should be with E42 electrode, welds for S275 material should be
with E35 electrode. Electrodes/welding consumables must have specified charpy impact
value equivalent to or better than the parent metal.
•
190
MARKING
Identifying and recording materials and components: Submit details of proposed methods.
Location of marks:
Generally: Visible for checking after erection.
Weathering steel: On surfaces not exposed to open view in the completed work.
• Steel to be blast cleaned, pickled, metal sprayed or galvanized: Marked so that subsequent
treatment cannot obliterate the marking.
•
•
195
•
HARD STAMPING
Usage: Not permitted except as indicated on drawings.
•
END CONNECTIONS
Angle cleats: Project 10 mm beyond ends of simply supported members.
210
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215A
•
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HOLLOW SECTIONS
Insides of sections: Debris and moisture removed before sealing ends and openings.
Seal all hollow sections with 5mm plate with continuous butt welds (ground flush for
exposed sections).
•
ACCESS/ VENTILATION HOLES IN BASE PLATES
Base plates larger than 1 m²: Make 25 mm diameter holes as necessary for pressure
grouting, escape of entrapped air or direct compaction of filling/ bedding material.
220
225A
STEELWORK TO BE GALVANIZED
Cutting, drilling and shop welding: Complete before galvanizing.
Vent and drain holes: Provide as necessary.
Locations: Submit proposals.
Sealing: Required, submit proposals.
• Detail and weld to limit distortions. Distortions after galvanizing to within specified limits of
the NSSS (seek advice from galvanizer prior to fabrication and inform engineer of likely
non-conformities). Follow welding and detailing advice of Galvanizers Association, in
particular "The engineers and architects guide to hot dip galvanizing".
•
•
WELDING
255
•
•
260
SITE WELDING
Usage: Permitted only where indicated on drawings.
Working conditions: Suitable and safe. Do not weld when surfaces are wet or when
ambient temperature is below 0°C.
WELDERS AND WELDING PROCEDURES
Test welders to BS EN 287:1 as appropriate using section types and thicknesses specified,
electrodes of appropriate class, welding positions approved for use in the work.
• Welding procedures to BS EN 288:2, unless otherwise agreed in writing with the engineer,
using consumables, equipment, welding positions and materials representative of those
proposed for the work. Submit evidence of procedures and weld certificates for approval by
the engineer.
•
270
•
ADDITIONAL WELDS
Welds (including tack welds) not indicated on drawings: Not permitted without approval.
290A
FINISHED WELDS
Finished welds: Carefully dressed to remove slag without deforming surface of weld, by
light hammering or wire brushing.
• Remove surface laminations, shelling, cracks, crevices, inclusions and other surface flaws
by chipping or grinding. Do not exceed limits specified in BS 4360 clause 10. If excessive
grinding or chipping required necessitating filling or welding is required, obtain engineer
approval.
• Uneven or oversize weld subject to Engineers written approval.
•
BOLT ASSEMBLIES
302
NON-PRELOADED BOLT/ SCREW ASSEMBLIES
Designation: Black bolts to BS 4190, grade 8.8 and Countersunk bolts to BS 4933, grade
8.8.
• Nuts and washers: To suit grade of bolt, as NSSS, clause 2.7.
• Coating applied by manufacturer: Galvanized as clause 370.
•
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304
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305
PROPRIETARY BOLT ASSEMBLIES
Manufacturer: Lindapter.
Product reference: Hollo-bolt grade 8.8 JS500 finish for connecting closed hollow
sections.
PROPRIETARY ANCHORS
Manufacturer: Hiliti or similar approved.
Product reference: to suit application.
• Anchor type: Thick-walled sleeve expansion anchor .
• Material: Carbon steel grade 8.8 galvanised for internal applications or A4-70 stainless for
cavity/external applications.
•
315
HOLDING DOWN SYSTEMS
Bolts:
Standard: To BS 7419.
Type: Hexagonal headed.
Grade: 8.8.
Diameter: M20 or otherwise indicated on drawings.
Coating: Galvanized.
• Bolt boxes: Contractor's choice.
• Anchorage: 100mm square x 12mm thick, grade S275 plate.
• Other requirements: Bolt shank to extend 100mm above top of concrete.
•
325
•
•
•
•
•
•
335
•
370
DIRECT TENSION INDICATORS
Standard: To BS 7644-1.
Manufacturer: Contractor's choice for HSFG bolts.
Product reference: Contractor's choice.
Grade: Appropriate for grade of bolt and nut assembly.
Finish: Sherardized .
Ancillary components: Washers to BS 7644-2. Used as recommended in BS 7644-1,
Annex A.
Post installation and inspection treatment: Where no further protective coating is specified,
apply a butyl rubber sealing compound to seal measuring gap around indicators.
SPRING WASHERS
Standard: To BS 4464.
GALVANIZED COATING TO BOLT ASSEMBLIES
Standard: To BS 7371-6.
Galvanizing: Applied by fastener manufacturer. Passivated and lubricated if no additional
coatings are specified. Nuts tapped after galvanizing.
• Use/location: All bolts.
•
•
390
•
SEALED HOLLOW SECTIONS
Bolt holes: Sealed to prevent access of moisture.
Method of sealing: Submit proposals.
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ERECTION
405
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410
OUTLINE METHOD OF ERECTION
All hot rolled steel elements comprise secondary or ancillary parts of the structure and
therefore are fixed back to the concrete frame which provides its stability. All members are
structurally stable when all connections back to the frame have been completed. The
external canopy relies on the metal deck roofing for permanent stability, but will be
temporarily stable before deck fitted if connections have been completed back to the frame.
PRE-ERECTION CHECKS
Scope: At least 7 days before proposed erection start date, check the following:
Foundations and other structures to which steelwork will be attached: Accuracy of setting
out.
Holding down bolts: Position, protruding length, slackness and condition.
• Inaccuracies and defects: Report without delay.
• Permission to commence erection: Obtain.
•
420A
•
425
•
•
432
SETTING OUT
Permissible deviations: In addition to the requirements of the NSSS, comply with the
following:
Type of dimension, location and Permissible Deviation:
Cladding/glass/window/door framing members: +/-5mm, distance between adjacent
members not to exceed +/-5mm than the dimension specified.
Maximum abrupt changes in continuous or jointed surfaces shall be 2mm.
MODIFICATIONS
Steelwork: Do not modify without approval.
Temporary fabrication/ erection attachments: Submit details and methods of removal.
TEMPORARY SUPPORT
Elements to be supported: Curved wall.
Bracing/Restraints: Provide as necessary until permanent connection can be made to perm
anent stable/braced structure.
• Forces and moments in elements: Make independent assessment, when in doubt ask
advice of engineer .
•
•
440
COLUMN BASES
Levels: Adjust using steel shims or folding wedges no larger than necessary.
Location of shims/ wedges: Position symmetrically around perimeter of base plate. Do not
use a single central pack.
• Give notice: If space beneath any column base is outside specified limits for bedding
thickness.
• Accuracy of erection: Check, and correct errors before filling and bedding beneath bases
and carrying out other adjacent work.
•
•
443
PROPRIETARY FILLING/ BEDDING OF COLUMN BASES
Bedding thickness range: 10-75mm (outside this range seek instruction from engineer).
• Preparation: Concrete surfaces scarified to provide a good mechanical key.
• Bolt pockets and spaces beneath base plates: Completely filled with Fosroc Conbextra HF
non-shrink grout in two operations: fill bolt boxes first. Provide formwork to contain grout as
Fosroc data sheet. Pre-soak with clean water 2 hours prior to application and remove free
water expecially in bolt boxes.
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447
MOVEMENT JOINTS
Sliding surfaces: Coated with molybdenum disulfide grease before connecting.
Appearance and fit: Bolts centred in slotted holes. Joints free to move.
BONDED ANCHORS
Holes: Clean and free from dust at time of installing anchor.
Permeable sleeves: Use in conditions where otherwise the loss of bonding agent would be
unacceptably high.
• Other requirements: Comply with manufacturers requirements with respect to cleanliness,
hole diameter, min depth where not indicated of drawings, min edge distances where not
indicated on drawings (where possible position to give maximum edge distance on all
sides) and curing requirements/times.
•
•
TESTING
465
TESTING
Testing: Arrange the following tests. Prepare test pieces as necessary.
Test: Welds and welders in accordance with NSSS.
Testing authority: UKAS accredited laboratory.
Frequency/ Number: As NSSS .
Level of acceptability: 100%.
Other requirements: None.
• Test and examination results: Submit 1 copies immediately they are available.
•
•
475
•
PRODUCTS
Steel: Submit test certificates.
PROTECTIVE COATINGS
505
•
•
•
•
•
•
521
GENERAL
Only items totally free from any contaminating matter affecting the life/durability of the
coatings shall be deemed clean and suitable for application of coatings.
Operatives must be appropriately skilled and experienced in the use of the specified
materials and methods of application.
Coating materials wherever possible to be from one manufacturing batch. Where more
than one batch is to be used keep separate, and allocate to distinct parts/areas of the
works.
Preparation of materials and ancillaries as recommended by their manufacturers. where
prefabrication primer is required apply interplate 180 25 microns dft.
All cutting, welding and drilling to galvanized members must be completed prior to
galvanizing.
Handling, storage and protection: use methods to minimise chafing, chipping and other
damage to coated components, ensure adequate curing prior to handling, use suitable
packing and nylon slings as appropriate, stach components clear of the ground separated
by timber chocks so that ponding does not occur, for galvanised components do not store
in damp conditions and guard against white rust. Protect freshly applied coatings damage
(mechanical, weather or otherwise). Make good any defects on site.
ALTERNATIVE MANUFACTURERS
Short list of manufacturers: Obtain coating materials from one only of the following:
Kemira, Leigh, International.
• Selected manufacturer: Submit details before ordering materials.
•
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545
•
•
•
•
•
•
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550
•
•
•
•
•
INSPECTION OF COATING WORK
Work in progress: Permit coating manufacturer to inspect and take samples of products.
Notice: Give notice of dates for:
Start of surface preparation and coating.
Coated members or components leaving the works.
Period of notice (minimum): 5 working days.
REMEDIAL WORK
Early degredation of coatings by blistering, peeling, flaking, cracking, lack of adhesion, etc
must be made good by complete removal, preparation and reapplication of all coats in
accordance with this specification or otherwise agreed in writing with the engineer.
inadequate dry film thickness or surface defects due to adverse weather may, depending
on the type of paint, be remedied by rubbing down and applying further coats as instructed.
Mechanical damage to coatings must be made good by local cutting back of coatings,
preparation by hand or power tool to St2 (ISO 8501-1) and reapplication of all coats to
leave a neat, continuous and flat finish, overlapping existing by at least 30mm.
touch up bear areas with Interplus 356 to meet original works dry fil thickness followed by
specified top coat. External exposed steelwork will require two coats.
Where damage to coatings or subsequent surface preparation has exposed the steel it
must be thoroughly cleaned and primed within two hours.
Re-execute any work undertaken with non-approved / untested material.
All remedial works to engineers or paint manufacturers approval.
INSPECTION AND TESTING FOR LIQUID METAL ASSISTED CRACKING (LMAC)
Visual inspection: Inspect galvanized surfaces for cracks or indications of LMAC cracking.
Extent: all galvanized steelwork.
Timing: Before erection of steelwork or application of other coatings.
Inspector: Submit, on request, evidence of training and competence in visual inspection
for LMAC.
Sites of suspected defects: Remove zinc coating by grinding back to bright metal for a
distance of not less than 50 mm around each defect and from a similar area on opposite
face of member.
Nondestructive testing:
Test locations: Areas where LMAC is suspected following visual inspection, and
corresponding areas of members with similar detailing.
Other locations: Highly stressed connections or otherwise indicated on drawings.
Test method: Ultrasonic testing to BS EN 1714 or otherwise agreed with the engineer.
Inspection and test reports: Submit as soon as available.
Repairs and recoating: Submit proposals.
PROTECTIVE COATING SYSTEMS
620
GALVANIZING TO BLAST CLEANED STEEL
Use/ location: Roof plant screens posts and beams / associated wind posts / all external
steelwork.
• Preparation: Blast cleaning to BS EN ISO 8501-1, preparation grade Sa2½ using chilled
angular iron grit grade G24 to give a coarse surface profile, followed by chemical cleaning.
• Galvanizing: To BS EN ISO 1461.
Minimum mean coating thickness: 140 micrometres.
•
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•
•
•
•
•
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642
•
•
•
•
•
•
•
SHOP PAINTING WITHTWO PACK FAST CURING - ZINC RICH PHOSPHATE
PROTECTIVE FINISH COMPLIANT COATING
Use/ location: All internal non exposed steelwork.
Paint manufacturer: contractor's choice.
Shop preparation: Blast cleaning to BS EN ISO 8501-1, preparation grade Sa 2½ ensuring
adequate surface profile.
Shop primer: as supplier's recommendations.
Dry film thickness: 75 microns nominal (increase to 175 for all steelwork that is
inaccessible / located in cavities) .
Shop intermediate coat: None.
Dry film thickness: N/A .
Shop top coat: None.
Dry film thickness: N/A .
Colour: N/A.
Special requirements: Max VOC 320gms/litre. volumne solids 67% To be compatible with
intumescent fire protection.
SHOP PAINTING WITHTWO PACK FAST CURING - ZINC RICH PHOSPHATE
PROTECTIVE FINISH COMPLIANT COATING
Use/ location: Internal architecturally exposed structural steelwork (AESS) other than
exposed steel to be intumescent coated (see M61).
Paint manufacturer: international Paint.
Shop preparation: Blast cleaning to BS EN ISO 8501-1, preparation grade Sa 2½ ensuring
adequate surface profile.
Shop primer: Intercure 200 HS (colour grey buff).
Dry film thickness: 75 microns nominal .
Shop intermediate coat: None.
Dry film thickness: N/A .
Shop top coat: Interfine 979.
Dry film thickness: 100 microns nominal .
Colour: As specified by architect.
Special requirements: Primer: Max VOC 339gms/litre. Volumne solids 67%. Top Coat:
Max VOC 240gms/litre. Volumne solids 76% To be compatible with intumescent fire
protection.
PREPARATION FOR PAINTING
710
OFFSITE PREPARATION AND PAINTING
Working area: Covered and properly lit, heated and ventilated.
Sequence of working: Select from the following and submit proposals:
Fabricate, blast clean, prime.
Blast clean, fabricate, remove flash rust with a light overall sweep blast, prime.
Blast clean, apply weldable prefabrication primer, fabricate, prime.
• Prefabrication primer (option 3): Type recommended by manufacturer of post fabrication
primer.
Thickness of post fabrication primer coat: May be reduced if and as recommended by
manufacturer.
• Surfaces inaccessible after assembly: Apply full treatment and coating system including, if
necessary, local application of site coatings.
•
•
725
•
•
•
MANUAL CLEANING OF NEW STEELWORK
Preparation: Remove fins, burrs, sharp edges, weld spatter, loose rust and loose scale.
Surface finish: Clean but unpolished to BS EN ISO 8501-1, grade St 2.
Finishing: Thoroughly degrease and clean down. Remove any consequent rusting back to
grade St 2. Prime without delay.
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735
PREPARATION FOR SITE WELDING OF SHOP PAINTED STEELWORK
Method: Select from the following:
Mask weld areas immediately after blast cleaning and before coating steelwork. If paint
system comprises more than one coat, step each coat 30 mm back from edge of
preceding coat and away from masked areas. Remove masking immediately before
welding.
Prepare and paint steelwork including weld areas. Grind off to bare steel around each
weld area immediately before welding.
TREATMENT OF SITE WELDED JOINTS IN PAINTED STEELWORK
Preparation: After welding, and without delay, remove scale and weld spatter from weld
areas. Remove traces of rust. Wash with clean water and allow to dry. Prime without delay.
• Protective/ Decorative coatings: Apply to weld areas to match surrounding painted areas.
•
736
TREATMENT OF SITE WELDED JOINTS IN GALVANIZED STEELWORK
Preparation: After welding, and without delay, remove scale and weld spatter from weld
areas. Remove traces of rust. Wash with clean water and allow to dry.
• Coating: Reinstate using one of the methods given in BS EN ISO 1461, clause 6.3.
•
740
BOLTED JOINTS (OTHER THAN FRICTION GRIP JOINTS)
Steelwork to be shop painted: Apply full shop specification to joint faces.
Steelwork to be erected with mill finish then site painted: Before erection, prepare and
prime joint faces and allow to dry.
• Bolted joints in externally exposed steelwork:
Immediately before assembling, apply a further coat of primer and bring surfaces
together while still wet.
After assembling and before applying site coatings, seal crevices to bolts and joint
perimeters with a compatible sealant.
•
•
755
•
UNCOATED FASTENERS
Treatment: After steelwork erection and before applying site coatings, thoroughly degrease
and clean. Without delay, coat to match adjacent shop painted areas.
•
GALVANIZED FASTENERS
Treatment: After steelwork erection and before applying site coatings, thoroughly degrease
and clean. Etch prime.
760
765
•
SITE PREPARATION OF SHOP PAINTED STEELWORK
Preparation: Touch in shop coats, as necessary, and allow to dry. Before applying site
coats (when specified), abrade surfaces or wash down or both, as recommended by paint
manufacturer.
PAINTING
810
•
ENVIRONMENTAL CONDITIONS
General requirements prior to starting coating work:
Surfaces: Unaffected by moisture or frost.
Steel temperature: At least 3°C above dew point, with conditions stable or improving,
and not high enough to cause blistering or wrinkling of the coating.
Relative humidity: Below 85%.
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815
COATINGS
Surfaces to be coated: Clean, dust free and suitably dry. Previous coats to be adequately
cured.
• Multiple coats of same material: Use different tints to assist checking of complete
coverage.
• Penultimate coat: Colour recommended by paint manufacturer to suit top coat colour.
• Finish required: Smooth and even, of uniform thickness and colour, free from defects.
•
820
FILM THICKNESS
Wet film thickness: During application, check thickness of each coat with a wheel or comb
gauge used in accordance with BS EN ISO 2808.
• Accumulated dry film thickness: After each coat has dried, check total accumulated film
thickness.
Method: Magnetic or electromagnetic meter.
Number and position of measurements: As directed.
Validation: Measurements to be independently witnessed.
Meter calibration: Check against standard shims and recalibrate regularly against a
smooth steel reference plate.
• Average dry film thickness:
At least specified thickness over any square metre.
No reading to be less than 75% of specified thickness.
• Top coat dry film thickness: Sufficient to give an even, solid, opaque appearance.
•
825
•
STRIPE COAT
External angles, nuts, bolt heads, rough weld seams, and areas difficult to coat: Apply an
additional stripe coat of 75 microns of primer specified .
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