J.01_USAID_Botswana_Houses_-_SOW.pdf

UNITED STATES AGENCY FOR INTERNATIONAL DEVELOPMENT

THE DEMOLITION AND NEW CONSTRUCTION OF TWO

USAID OWN RESIDENCES AT PLOT 2483 TSHEKEDI

CRESCENT AND PLOT 3064 MARAKANELO WAY IN

GABORONE, BOTSWANA

SCOPE OF WORK

DOCUMENT

Prepared by:

David Hough

PKA International Architects 37 Garstfontein Road

Waterkloof Pretoria

South Africa

Table of Contents

01. Introduction 1

01.1 Purpose 1

01.2 Background 1

01.3 Project Particulars 1

01.4 Conditions and exclusions 2

01.4.1 Conditions 2

01.4.2 Exclusions 2

01.5 Locations of sites 2

02. Scope Specifics 5

02.1 Preliminary and General items 5

02.1.1 Fixed Charge Items 5

02.1.2 Time Related Items 6

02.1.3 Health, Safety and Environmental 6

02.2 Builders Work 6

02.2.1 Demolitions and alterations 7

02.2.2 Earthworks 7

Nature of the ground: 7 Carting away of excavated material: 7 Site Clearance: 7 Tree removal: 8 Benchmark: 8 Dust and noise: 8 Cleaning site on completion: 8

02.2.2.1 Excavations 8

Class of excavation material assumed 9 Blasting 9 Excess soil 9 Excavations for foundations 9 Reducing levels 9 Storm- and ground water 9

02.2.2.2 Fill 9

Earth 9 Blinding material 10 Topsoil 10 Stormwater removal 10

02.2.2.3 Termite control 10

Soil poisoning 10 Guarantee 10

02.2.3 Conc rete, formwork and reinforcement 11

02.2.3.1 Concrete 11

Cement 11 Aggregates 11 Water 11 Concrete mix 11 Readymix concrete 11 Reinforcement 11 Sleeves 12 Ties 12 Transporting, placing, compaction 12 Pumping 12

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Testing 12 Curing 12

02.2.3.2 Applications 13

Foundations 13 Slabs on masonry walls 13 Formwork 13 Floors on ground 14 Joints 14 Reinforced concrete lintels 15

02.2.4 Precast concrete 16

Materials 16 Casting 16 Patents 16 Samples 16 Marking 16 Storing and curing 16 Handling 16 Damaged units 16 Building in precast units 16

02.2.5 Masonry 16

02.2.5.1 Bricks and blocks 16

Clay bricks 16 Compressive strength 17 Stone 17 Proof of quality 17 Samples 17 Storage 17 Reinforcement 17 Lintels 17

02.2.5.2 Mortar 18

Cement 18 Sand 18 Lime 18 Mixing 18 Mix proportions 18

02.2.5.3 Masonry walling 19

Bond 19 Laying bricks and blocks 19 Cavity walls 19 Face work 20 Smoke flues 20 Building in 20 Movement and control joints 20 Lintels 20 Masonry testing 21

02.2.6 Waterproofing 21

02.2.6.1 Damp-proof courses, membranes and vapor barriers 21

02.2.6.2 Waterproofing 21

Material and application 21 Quality control 22 Preparation 22 General application 22 Testing 23 Protection 23 Guarantee 23

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02.2.6.3 Joint fillers / sealants 24

Material 24 Preparation 24 Sealing 24

02.2.7 Roof coverings 24

General 24

02.2.7.1 Profiled roofing and cladding sheets 25

Metal roof sheeting 25 Profile 25 Storing roof sheets 25 Fasteners and washers 25 End laps and purlin spacing 25 Fixing 25 Ridgings, closers 25

02.2.8 Carpentry and joinery 26

02.2.8.1 Timber roof systems 26

Materials 26 Timber 26 Fasteners 26

Handling and erection of trussed roof structure 27 Certificate of approval of trussed roof structure 27 Wall plates 27

02.2.8.2 Cornices, skirtings, rails 28

02.2.8.3 Timber doors 28

Doors 28 Storage 28 Hanging 28

02.2.8.4 Timber for joinery 29

Timber 29

02.2.8.5 Joinery 29

Preparation 29 Joinery 29 Shelf bands 29 Fixing to walls 30

02.2.8.6 Decorative laminates 30

Material 30

02.2.8.7 Kitchen Cupboards 30

Cupboards 30 Fixing 30 Adjusting 30

02.2.9 Ceilings 30

02.2.9.1 Timber ceiling brandering 30

Timber 30 Size and spacing 30 Fixing 31

02.2.9.2 Fibre-cement and gypsum ceilings 31

Board 31 Fixing 31

02.2.9.3 Cornices 31

Material and fixing 31

02.2.9.4 Patent suspended ceilings 32

Suspension fittings 32

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Fixing 32

02.2.9.5 Ceiling Insulation 32

Insulation 32

02.2.9.6 Ceiling hatch 32

Steel hatch 32

02.2.10 Ironmongery 33

02.2.10.1 Ironmongery 33

Locks, latches, handles, plates, closers etc. 33

02.2.11 Structural steelwork 33

02.2.11.1 Structural steelwork 33

Competent Person 33 Steel 33 Shop drawings 33 Welding 34 Dressing 34 Prepainting 34 Structural fasteners 34 Grouting 34 Accuracy 34 Quality assurance 35 Certification 35

02.2.12 Metalwork 35

02.2.12.1 Pressed steel door frames 35

Building in of frames 35

02.2.12.2 Aluminium frame windows and doors 35

Glazed aluminium windows and sliding doors 35 Glass 35 Design 35 Installation 35

02.2.12.3 Steel roller shutters and doors 36

Slats 36 T-bars 36 Guides 36 End plates 36 Barrel or shaft 36 Operation 37 Fixing 37

02.2.12.4 Stainless steel balustrades 37

Stainless steel 37 Welding 37 Cleaning 37 Handrailing and balustrading 37

02.2.13 Plastering 38

02.2.13.1 Plaster 38

Cement 38 Sand 38 Lime 38 One-coat cement plaster, bagging or roughcast 38 Gypsum plaster 38 Preparation 38 Plastering 39 Accuracy 39

02.2.13.2 Toppings and screeds 39

Cement 39 Aggregate 39 Topping 39 Screeds 40

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Preparation 40 Laying 40 Finishing 41 Joints 41 Accuracy 41 Thresholds and stair treads 41 Dividing strips 41 Curing 42 Inspection, testing and repair 42 Finishing 42

02.2.14 Tiling 42

02.2.14.1 Material 42

Ceramic tiles 42 Mosaic tiles 42 Samples 42 Adhesive 42

02.2.14.2 Tiling 42

Preparation 42 Fixing tiles 43 Fixing mosaic tiles 43 Pattern 43 Angles 43 Sills and thresholds 43 Grouting and pointing 43 Movement joints 43 Cleaning 44

02.2.15 Plumbing and drainage 44

02.2.15.1 Roof flashings and linings 44

Metal 44 Flashings 44 Fixing 44

02.2.15.2 Eaves gutters and downpipes 44

Sheet metal 44

02.2.15.3 Roof and floor outlets 45

Rainwater outlets 45 Outlet pipes 45

02.2.15.4 Drainage and water supply 46

Standard 46

02.2.15.5 Below ground soil water drainage 46

Cleaning eyes 47 Inspection eyes 47 Gulleys 47 Testing of sewers 47

02.2.15.6 Above ground soil and waster water drainage 47

PVC-U soil waste and vent pipes 47 Fixing pipes above ground 47

02.2.15.7 Water supply 48

Galvanized mild steel pipes 48 Copper pipes 48 Thermoplastic pipes and fittings 48 Polyethylene (PE) pipes 48 Installation of pipes 49 Standard: 49

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Water meters 50 Cleaning 50 Insulation 51

02.2.15.8 Electric geysers and solar water heaters 51

Solar water heaters 51

02.2.15.9 Sanitary appliances 51

Appliances 51 Taps and valves 51 Traps 51 Fixing of sanitary fittings generally 52

02.2.15.10 Fire equipment 52

Fire extinguishers 52 Fire hydrants 52

02.2.16 Electrical 52

02.2.16.1 Electrical installation 52

02.2.16.2 Guarantee 52

02.2.16.3 Materials 52

Conduits 52

Switches and sockets 53 Luminaires 53 Stoves 53

02.2.16.4 Test 54

02.2.17 Glazing 54

02.2.17.1 Materials 54

Glass 54 Sealants 54 Gaskets, tape, setting blocks 54

02.2.17.2 Glazing 54

Preparation 54 Glazing with compounds 55 Protection and cleaning 55 Warranties 55

02.2.17.3 Mirrors 55

02.2.18 Painting 56

Paint 56 Preparation 56 Colours 56 Painting in general 56

02.2.18.1 Painting 56

Clear finish on woodwork 56 Alkyd paint on plaster 57 Emulsion paint on plaster 57 Emulsion paint on fibre-cement fascias and cladding 57 Emulsion paint on gypsum ceilings 58 Alkyd paint on structural steel 58 Alkyd paint on non-structural steel 58

02.2.19 Externals Works 58

02.2.19.1 Concrete block paving 58

Concrete blocks 58 Samples 58

Edge restraints 59 Infill concrete 59

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Weed killer 59 Levels, falls, pattern 59 Flexible paving 60 Cutting 60 Tolerances 60 Cleaning 60 Trial Section 60

02.2.19.2 Concrete kerbs 60

Precast kerbs 60 Mortar 60 Bedding material 60 Backing concrete 60 Joint sealant 60 Laying 60 Tolerances 61

02.2.19.3 Gabions 61

02.2.20 Swimming pools 61

02.2.21 Landscaping 61

Definition of terms 61 Cleaning of site 61 Soil preparation 61 Plant quality 62 Planting 63 Hydroseeding 63 Tree supports 63 Maintenance 64 Geomembranes 64

02.3 Heating, Ventilation and Cooling Installation 65

02.3.1 General 65

02.3.1.1 Scope of work 65

02.3.1.2 Statutory and Regulatory requirements 65

02.3.1.3 Manufacturer’s ratings 66

02.3.1.4 Protection of Works 66

02.3.1.5 Visit to site 66

02.3.1.6 Time for completion 66

02.3.1.7 Guarantee 66

02.3.1.8 Erection 66

02.3.1.9 Materials and Workmanship 67

02.3.1.10 Drawings 67

02.3.1.11 Operating and maintenance manual 68

02.3.1.12 Maintenance and servicing 69

02.3.1.13 Cleaning of equipment and site 69

02.3.1.14 Inspection and testing 69

02.3.2 Detail technical requirements 69

02.3.2.1 Noise levels 69

02.3.2.2 Split type air conditioning units 69

02.3.2.3 Ceiling mounted extraction fans 70

02.3.2.4 Refrigerant tubing 70

02.3.2.5 Electrical 71

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03. Permits 71

04. Schedule 71

05. Quality management 72

06. Preferred Contractors or Suppliers 72

07. Drawings 72

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01. Introduction

01.1 Purpose

The purpose of this document is to adequately define the Scope of Works required for the construction of two houses for the United States Agency for International Development (USAID) in Gaborone, Botswana. Terms of reference will be provided the Contractor to supply a detailed price, schedule and method statement necessary to execute the Scope of Works in an efficient, safe and cost effective way as required by USAID.

01.2 Background

The limits of the works are contained on two separate plots owned by USAID in Gaborone, Botswana. The first, Plot 2483 Tshekedi Crescent, and the second, Plot 3064 Marakanelo Way. Both plots currently accommodate existing homes.

The home on Plot 2483 Tshekedi Crescent was built in 1975 and measures 203m2. Recent renovation work conducted over the years have rendered the house functional but in fair to poor condition. The plot measures approximately 2641m2. Plot 3064 Marakanelo Way measures 4189m2 in area, hosting an existing home of 374m2 which was built in 1978.

In 2017, USAID employed an architectural firm to survey the condition of the home on Plot 3064 Marakanelo Way and to develop designs and cost estimates for the renovation and re-construction of the home. No significant cost difference was found between renovation and reconstruction. As such, USAID has decided to demolish the existing homes on both plots and build two new houses on Plot 2483 Tshekedi Crescent.

01.3 Project Particulars

An architectural and engineering team has been appointed by USAID to develop the necessary drawings and specifications required to deliver two double storey contemporary and secure residential homes for USAID staff and their families in Gaborone, Botswana.

The gross building area of each home is 542m2 and includes habitable rooms such as:

• Living area,

• Dining area,

• Kitchen,

• Scullery & Laundry,

• Staff quarters,

• Four bedrooms with en-suite bathrooms,

• Study,

• Guest bathrooms, and

• TV lounge.

Ancillary areas include:

• Double garage,

• Stores,

• Patios and verandas,

• Undercover Entrances.

In addition to the above, the project also includes demolition work, landscaping of the site, a gatehouse, and various external works such as paving. Further detail regarding these items will be detailed later in this document.

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01.4 Conditions and exclusions

01.4.1 Conditions

The Contractor submits their bid under the following conditions:

• The price submitted is firm and fixed with a validity period of 60 days.

• The Contractor has visited the sites, reviewed the drawings and specifications, Scope of Work, and Bill of Quantities in order to familiarize themselves with the full extent of services required by USAID.

• The price of the Contractor includes the necessary measures to comply with the Health, Safety and Environmental requirements of USAID.

• The Contractor will obtain the necessary permits and authorizations as may be applicable to carry out the works.

Copies of these are to be kept on site at all times.

• The Contractor has allowed for the necessary costs to secure, establish and maintain a safe and healthy site and work environment throughout the construction period, in accordance with specific requirement criteria of SABS 1200A.

• This Scope of Work document, together with the drawings, specifications and priced Bill of Quantities are legally binding documents that will eventually form part of the contract documentation.

01.4.2 Exclusions

The following items will be excluded from the Scope of Works:

• Procurement of loose items including:

• Furniture,

• Curtains,

• Cutlery and crockery,

• Appliances,

• Artwork and decorations,

• Cleaning equipment and utilities,

• Electronics,

• Bedding and linen,

• Sport facilities such as tennis courts etc.

• Access roads outside of the site.

• Piling.

• Diversion of services.

01.5 Locations of sites

The locations of Plot 3064 Marakanelo Way and Plot 2483 Tshekedi Crescent are indicated by the ensuing aerial photographs below.

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PLOT 2483

TSHEKEDI

CRESCENT

PLOT 3064

MARAKANELO

WAY

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PLOT 2483

TSHEKEDI

CRESCENT

PLOT 3064

MARAKANELO

WAY

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02. Scope Specifics This Scope of Work is outlined by the following main components:

• Preliminary and General items,

• Builders Work, and

• Heating, Ventilation and Cooling Installation.

Specifics for each item are explained in detail under each section of this document.

02.1 Preliminary and General items

Preliminary and General items are an estimate of the costs on Contractor’s plant and equipment deployment on the project during construction. This should also include salaries for the workforce as well as insurances and provision for water & electricity for the works. The contractor’s costs for complying with safety, health and environmental legislation should be calculated as part of Preliminary and General items. Typically these can be broken up into fixed charge items, time related items and health and safety, which will be further detailed and itemized in the Bill of Quantities. Items that are not priced are deemed to be included and covered in the Contractor’s rates.

02.1.1 Fixed Charge Items

The fixed charge items generally include items such as:

• Facilities for the Architectural and Engineering team such as a site diary and site instruction book.

• Facilities for the Contractor including offices, workshops, on-site storage facilities, living accommodation, ablutions, tools and equipment, water supplies, electrical power, and communications equipment.

• Further items that require special attention include but are not limited to:

• Services of skilled engineers and personnel.

• Organizational charts.

• Cash flow schedules.

• Labour and plant reports.

• Site meetings.

• Cleanliness during construction.

• Permits for demolition and excavation.

• Transport and delivery of materials.

• Site storage of materials,

• Quality assurance and control.

• Subcontractors.

• Site access.

• Regulatory and informational signage.

• Monthly statements and payment certificates.

• Contractors representatives and site personnel.

• General setting out.

• Employment of local labour.

• Medical examinations.

• Permit regulations and inductions.

• Guarantees.

• Security.

• Laboratory tests and results.

• Plant requirements.

• Scaffolding.

• Transport of

• Plant and equipment to site, and

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• Workforce to and from site.

• Removal of site establishment on completion.

• Sundry expenses.

• Fencing of construction site.

02.1.2 Time Related Items

Time related items include but are not limited to:

• Contractual requirements such as insurances, programming, retention and compliance with laws and legislation.

• Establishment of facilities on the site including furnished offices and a site meeting venue.

• As-built/record drawings.

• Samples and certification of materials.

• Protection of existing services.

• First aid and safety.

• Supervision for duration of construction.

• Company and head office overhead costs for the duration of the contract.

02.1.3 Health, Safety and Environmental

The Contractor is expected to familiarize themselves with the local Health, Safety and Environmental requirements and price for these accordingly.

These items typically include but are not limited to:

• Supply of work wear for labour force including overalls, hard hats, gloves, eye protection and safety boots/shoes etc.

• Training and certification for identified Site Health and Safety

Officer.

• Costs related to the implementation and training required in terms of Health, Safety and Environmental requirements.

• Provision of safety equipment items such as harnesses.

• Safety related inspections for equipment and plant.

02.2 Builders Work

The primary components included under the builders work are described below, with further detailed specifications included:

• Demolition of the two existing residences on each plot.

• Construction of two new residences measuring 542m2 in area including their internal and external finishes.

• Construction of a gate house measuring 16m2 in area including its internal and external finishes.

• Earthworks including site clearance, excavation of trenches, filling and application of soil insecticides.

• Plumbing and sanitary ware appliances.

• Permanent fixed items such as staircases, balustrades, roof structures and built-in barbecues.

• Doors and fenestration including their frames, glazing, hinges, locks, handles and other ironmongery.

• Ceilings, cornices and insulation.

• Louvres, access ducts and pergolas.

• Plastering and finishing/painting of walls.

• Tiling of floors and walls.

• Carpentry, joinery and shopfitting such as built-in cupboards, kitchen counters, shelving and cabinets.

• Metalwork including security grilles.

• Waterproofing.

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02.2.1 Demolitions and alterations

The Contractor must adequately price to safely demolish and remove all existing buildings and structures as per the relevant drawings and specifications, including:

• Building contents,

• Applying for and obtaining certification from Authorities,

• Safely terminating existing services,

• Excavating for and removing foundations,

• Filling in voids with suitable material as specified by the

Engineer, and

• Responsible and legitimate disposal of all rubble off-site.

Primary elements identified for demolition include:

• Residences including their fittings, fixtures and contents such as walls, floors, doors, windows, ceilings, roofs etc.

• Staff quarters and outbuildings including their fittings, fixtures and contents such as walls, floors, doors, windows, ceilings, roofs etc.

• Existing swimming pools including structure, pool pumps and piping, concrete bases, paving apron and surrounding steel fence.

• Existing boundary walls on the eastern and western boundaries of Plot 2483 Tshekedi Crescent inclusive of vehicle and pedestrian gates and associated foundations.

• All paving within the plot including layerworks and bedding material.

• Existing sewer manholes not exceeding 1000mm deep.

• Existing water storage tanks including support base, piping and pumps.

• Existing garden taps inclusive of piping.

• Reinforced concrete ground slabs.

Demolished material is the property of the contractor. No credit must be allowed to the employer, unless otherwise specified.

02.2.2 Earthworks

Nature of the ground:

The Contractor shall acquaint himself by personal examination of the nature of the ground. A geotechnical survey of Plot 2483 has been conducted and can be made available to the Contractor on request.

Descriptions of excavations shall be deemed to include all ground conditions classifiable as “soil” and where conditions of a more difficult character are indicated these are separately measured.

Carting away of excavated material:

Descriptions of carting away of excavated material shall be deemed to include loading excavated material onto trucks directly from the excavations or alternatively, from stock piles situated on the building site.

Site Clearance:

The Contractor is to allow for the stripping of a 150mm thick layer of top soil and depositing in prescribed stock piles on site. Stock piles are to be kept free of foreign organic material and protected against erosion during the construction period.

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Tree removal:

The Contractor must remove trees as shown on the drawings and extract roots where these occur under new buildings or paving under construction. Stump holes are to be filled with an approved filling material.

Benchmark:

The Contractor will set up a site datum level based on an established benchmark/s, as indicated on the drawings. Maintain and protect these benchmark/s.

Dust and noise:

Use methods that keep dust, noise and vibration to acceptable levels, and which leave adjoining structures safe, to the approval of the local authority.

Cleaning site on completion:

At completion of the works, the Contractor will dig up concrete or mortar mixing platforms, and clean the site of all surface and buried rubble.

02.2.2.1 Excavations

Classification of excavated material by hand:

Soil means soil which can be removed with hand tools and includes sand, made-up ground, gravel, clay, shale and loose stones not more than 75mm wide Soft rock means rock which can be loosened by hand pick axe or crowbar and includes hard shale, compact gravel-stone, stone of equal hardness and boulders at least 75mm wide and with a volume of not more than 0,03m3

Hard rock means granite, quartzite, sandstone, solid shale, slate and rock just as hard or harder, as well as boulders with a volume of at least 0,03m3

Classification of material excavated by machine:

Soft excavations means excavations in material which can be efficiently removed by

• back actor with fly wheel power of approximately 0.10kW per millimeter of tined-bucket width without the assistance of pneumatic tools;

• rubber tyred front end loader with a mass of about 15t and flywheel power of ± 100kW, without ripping or stockpiling.

Intermediate excavations means excavations in material which can be efficiently removed by

• back actor with flywheel power of more than 0.10kW for every millimeter of tined-bucket width;

• with the assistance of pneumatic tools;

• be loaded by rubber tyred front end loaders with a mass of about 15t and flywheel power of ± 100kW, without ripping or stockpiling.

Hard rock excavations means excavations in material which cannot be efficiently removed without blasting, or by wedging and splitting Boulder excavations class A means excavation in material which contains more than 40 % by volume of boulders between 0,03m3 and 20m3 in size, in a matrix of softer material or smaller boulders Boulder excavations class B means excavation in material which contains less than 40 % by volume of boulders between 0,03m3 and 20m3 in size, in a matrix of softer material or smaller boulders.

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Class of excavation material assumed The Contractor should assume all excavations are in material classified as soil or as soft excavations, unless specified differently.

Notify the architect/principal agent if harder material is encountered.

Blasting If blasting is required, obtain written approval from the architect/ principal agent and carry out the work in compliance with the latest state and local authority regulations.

Excess soil Spread excess soil over the site and roughly level, keep aside for filling later if required, or cart away to a suitable dumping site to be found by the contractor, outside the boundary of the site, as directed by the architect/principal agent.

Excavations for foundations Set out foundations accurately. Make regular checks on trench widths, squareness, distances to boundaries and adjacent structures.

Excavate to at least 400 mm below the level of the adjoining natural ground for strip foundations, and to at least 300 mm for slab-on-the-ground foundations, or down to firm natural ground or to solid rock, or to a depth as specified. Remove soft spots and backfill.

Only the Engineer will determine firm natural ground.

If excavations for foundations are dug too deep, fill up with grade 10 concrete at own expense.

Form steps in trench bottoms with horizontal and vertical surfaces where necessary, except where there is solid rock. Steps must be in multiples of masonry courses.

Clean the bearing area of solid rock and provide steps or dowels to prevent lateral movement.

In the case of expansive, consolidating or collapsing soil, when specified, remove soil to 1 m beyond building perimeter, and replace with engineered fill.

Give sufficient notice to the architect/principal agent for approval of foundation excavations before concrete is cast.

Reducing levels Excavate the ground outside buildings to reduced levels as specified or to a depth determined by the architect/principal agent. Sloping banks must be of such gradient as will maintain the stability of the ground above.

Storm- and ground water Protect excavations against flooding by stormwater or seepage by pumping or baling.

02.2.2.2 Fill

Earth Use approved clean, moist earth or gravel without clay or organic matter for general filling work under floors, paving, etc.

Provide test results of the filling material well in advance of ordering.

Engineered fill is fill which has been placed and compacted under the direction of a Competent Person within a defined moisture range, and in layers, by compaction equipment to defined density requirements, and which provides adequate bearing capacity for foundations and slabs.

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Do not fill around the foundation structure before this has been inspected and approved by the architect/principal agent.

Ensure that foundation walls are adequately supported and have adequate strength to withstand the horizontal pressures resulting from compaction.

Spread, level and compact filling under floors at optimum moisture content in layers not exceeding 100mm for hand compaction and 150mm layers for mechanical compaction, to a specified by the Engineer.

Use hardcore consisting of stone, hard-burnt brick or broken concrete ranging in size from 25 to 75mm, without fines, well consolidated by ramming, under floors or against basement walls, where specified.

Blinding material Use sufficient sand, fine gravel or other approved fine material to fill voids, providing a close smooth surface of hardcore which is to receive concrete, surfaces which are to receive damp proof membranes and where there is a likelihood that the membrane will be damaged, or where specified.

Topsoil After the site has been cleaned at completion of the works, spread, level and lightly consolidate topsoil temporarily stored on site, or carted in as directed, in one layer at least 75mm thick.

Fill against the outside of foundation walls with a minimum fall of 1:30 away from the building(s) over a distance of at least 1,5 meters, or as specified.

Stormwater removal Shape ground levels so that no water ponds against or within the first meter from the external perimeter of the building.

Ensure that stormwater does not pond against freestanding walls by providing adequate openings in the walls at the lowest levels, as specified on the drawings.

02.2.2.3 Termite control

Soil poisoning Poison the soil against the inside of foundation walls and under floors with Chlordane soil insecticide complying with SANS 1165, applied according to SANS 10124:

• by a certified pest control contractor

• not when soil is excessively wet

• do not disturb treated surface

• do not bury scraps of timber in ground fill

• treat foundation trench bottoms before casting

• treat every 300 mm backfill before compacting

• treat full length of pipe and cable trench inside the building and for a distance of 3 m outside the building

• take necessary health precautions on site.

Guarantee Obtain a written guarantee from the pest control contractor for ten years for the effectiveness of the treatment, and hand over to the architect/principal agent.

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02.2.3 Concrete, formwork and reinforcement

02.2.3.1 Concrete

Cement Use common cement to comply with SANS 50197-1, strength class 32,5N or higher.

Cement must be SABS-mark bearing. Type, composition and strength of the cement must be shown on the bag, or on the delivery slip of bulk cement.

Keep bagged cement in a dry store. Always use the oldest cement first. Do not use bagged cement with lumps that cannot be crumbled by hand.

Aggregates Use natural, crushed or blended sand for use in concrete to comply with SANS 1083, evenly graded, with the coarsest sizes passing the 4,75mm sieve.

Stone for use in concrete is to comply with SANS 1083, of 19mm single-size when mechanically mixed, and 13,2mm when hand-mixed. Stone size should not exceed clearance between reinforcement and formwork.

Supply aggregate test results to the architect/principal agent.

Keep supplies of sand and stone for fair-face concrete uniform throughout the contract. Ensure that adequate quantities of rock of the desired colour is established before work begins. Consider stockpiling. Keep grading of aggregates constant throughout the contract.

Store aggregates separately to prevent contamination.

Water Use drinking water. Have water tested if in doubt.

Concrete mix Mix proportions to produce the specified grade of concrete at 28 days or better may be arrived at by a process of mix design, by the use of recognized tables of trial mixes with aggregates, or according to the cement manufacturer’s instructions. Provide proof that mix proportions have been designed by a Competent Person.

Mix cement, sand and stone by volume for small jobs, or by mass where sophisticated equipment is available. Hand mix on a clean, hard surface.

Add just enough water to produce a workable consistency.

Measure consistency with the standard slump test as described in SANS Method 5862.

Readymix concrete Where the use of readymix concrete is allowed, the following applies:

• it must comply with SANS 878

• the supplier is responsible for the quality of the material and the design of the mix

• delivery tickets must be kept for inspection

• prepare at least three test cubes from every 50m3 of concrete and have tested as described under testing.

Reinforcement Use steel bars for concrete reinforcement complying with SANS 920, of type and nominal size as specified. Use welded steel fabric for concrete reinforcement complying with SANS 1024, of surface

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N and fabric reference number as specified by the Engineer.

Store steel off the ground so as to prevent distortion. Protect from aggressive environments and contamination.

Cut and bend reinforcement and fix. Overlap fabric mats by 300 mm. Reinforcing must not be welded.

Maintain cover over reinforcement according to ARP 040, measured from the face of the concrete to the outside of nearest main reinforcement.

Sleeves Cast into slabs and beams where indicated on drawings galvanized mild steel or plastic sleeves of diameter suitable to house service pipes up to 100mm in diameter. For larger service pipes form ducts to sizes as specified.

Ties Cast in 600 x 30 x 1,2 mm galvanized mild steel ties 150 mm deep, at about 500 mm centers, where brickwork abuts concrete. Where such fixing is impossible, e.g. where steel formwork is used, shot-nail the ties to the concrete.

Transporting, placing, compaction Ensure availability of skilled personnel in sufficient numbers to carry out the work.

Ensure all equipment necessary for mixing, transporting and vibrating concrete is in working order.

Ensure concrete quantities are adequate for the planned placement.

Cast walls, beams and columns in single lifts not less than one storey in height.

Take special care with the bottom 200mm of a new lift, for example by increasing the proportion of sand in the mix or by reducing the stone content by ±20%.

Transport fresh concrete in a way that does not cause segregation.

Deposit concrete in layers not more than 150mm for hand compaction, or 450mm for poker vibration.

Hand compact with spade or rod to free trapped air. Use a poker vibrator under supervision and by trained personnel. Strike off surface of concrete level.

Pumping Where pumping is required, the following applies:

• slump shall not exceed 125mm

• graded aggregate and suitable admixtures are used, wherever necessary, with a view to improving the pumpability of the mix

• its shrinkage capacity shall not be more than 10 % higher than that of ordinary concrete mixes.

Testing Cast three concrete test cubes of 150 x 150 x 150mm in accordance with SANS test method 5861.

Have these test cubes tested for compressive strength by an approved laboratory, all according to SANS test method 5863 and issue records of the results to architect/principle agent.

Curing Ensure continued hydration by curing the concrete with an application of a liquid membrane-forming curing compound at an approved rate; by ponding with water; by covering with polyethylene or similar vapor-proof material in large sheets. Cure for 7 days, and longer when the ambient temperature falls below

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10ºC. Building work may start on foundations in earth trenches the day after casting.

02.2.3.2 Applications

Foundations Cast unreinforced strip footings or slab-on-the-ground foundations of grade 10 concrete or better, to sizes as specified by the Engineer.

Reinforced foundations must be of grade 25 concrete or better.

Place reinforcement in strip footings centrally with a minimum side cover of 50mm. Place reinforcement in thickened footings and edge beams in slab-on-the-ground foundations at the bottom with a minimum side and bottom cover of 50mm.

Reinforce slab-on-the-ground foundations with fabric ref 193 for slabs up to 125m², and fabric ref 245 for slabs from 125—200m², placed centrally within the slab thickness and lapped by one full grid width.

Slabs on masonry walls Concrete slabs on masonry walls must have a minimum end bearing of 90mm.

Provide slip joints between wall and in situ concrete slabs or beams by troweling smooth the bearing surfaces and covering the bearing area with two layers of 0,25mm polyolefin sheeting. Provide similar slip joints above in situ slabs beneath masonry, turned up to break contact with screed or topping.

Separate the ends and sides of slabs from masonry with strip material specified by the Engineer.

Formwork Discuss the type of formwork, void formers, fixing of reinforcement, selection of spacer blocks, and detailing of joints and tie-bars with the architect/principal agent before any shuttering is ordered or brought on site.

Use formwork that will achieve the following surface finishes, as specified. Prepare a sample panel of at least 1m2 for approval, when specified. The sample panel must include all salient points like construction or day joints, splayed edges and tie-bar treatment.

Rough: shutterwork and tie-bars to no specific pattern, no treatment of the concrete surface after removal of the formwork, and the surface within the degree of accuracy 3 complying with

SANS 10155

Smooth: If small defects like honeycombing, irregularities and discolouration can be made good according to approved methods, and the surface is within degree of accuracy 2 complying with SANS 10155. Make this formwork of metal or wrot timber. Fit tie bars and joints in a regular pattern to the approval of the architect/principal agent. Strike horizontal day joints true and level with a trowel.

Special: Smooth, dense well-compacted concrete showing the slight grain marks of planed boards or smooth plywood with well-fitted joints and sound arises, with a surface within degree of accuracy 1 complying with SANS 10155. Shuttering panel and tie-bar layout must be as agreed. Make good any blemishes.

Formwork must be grout-tight and properly supported. Cover formwork faces in contact with concrete with a recognized release agent, taking care not to contaminate any reinforcement.

Remove any concrete from formwork after stripping.

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Formwork ties permanently cast in are subject to approval. Tie-wires are not permitted.

Use void formers that are manufactured from material which will not leak, tear or be damaged during the course of construction, and of such tight construction as to prevent undue loss of the mortar component of the concrete through leakage. Do not support void formers on the reinforcement.

Splay visible edges to columns and slabs, or as specified.

Form drips to bottoms of exposed slabs, lintel and beam edges.

Ensure minimum cover of reinforcement is 25mm inland and 50mm in coastal areas. Allow extra cover over steel reinforcement if material is to be removed from the surface by tooling or abrasive blasting.

Ensure beams have a camber of 6mm to every 3m of length.

Strip formwork only when concrete has attained the required crushing strengths. Determine the crushing strengths by proper tests, and with regard to the type of structural member, the strength class of cement used, and the weather. Maintain constant stripping times to assist in achieving colour uniformity in the case of fair-face concrete.

Floors on ground Use grade 15 concrete for surface beds to be covered with a screed. Do not trowel the surface, so as to provide a key for the screed.

Use grade 20 concrete for direct-finished one-course concrete domestic floors. Use the delayed troweling technique to finish the surface.

Cast floors to 75mm thickness, or as specified by the Engineer.

Cast concrete surface beds without contraction joints. Cast in 200 x 200 x 4mm ref 100 welded steel mesh to comply with SANS 1024, placed near the top surface, if specified. Use large mats.

Overlap mats by at least 300mm.

Place, compact, level, strike off, and wood float concrete floors to a level surface. Then finish the surface using the delayed trowelling technique, as follows:

• leave the surface undisturbed until bleeding has ceased and the surface has stiffened so that foot pressure barely indents the surface (2—4 hours)

• remove bleed water and laitance on the surface

• trowel using pressure, or power trowel. Steel trowel to produce a smooth finish, wood float to produce a slip-free surface. Do not add water. Do not add neat cement.

• in the case of domestic floors, concrete may be cast in room-size panels, with butt joints against thresholds. In the case of industrial floors, form contraction, construction and isolation joints as described below. In the case of columns, cast the concrete against edge forms placed diagonally to the column, and afterwards fill in the area between the column and the concrete already cast.

Joints Form joints in concrete floors as follows:

• Contraction joints: Provide contraction joints in an agreed pattern or as specified. Saw contraction joints with a mechanical concrete saw to blade width and a depth of one quarter of the slab thickness. Saw only after the concrete has hardened sufficiently but before shrinkage cracking can occur (between 4 and 48 hours after placement).

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• Construction or day joints: Cast construction joints at the end of the day’s casting or where concreting has stopped for more than 45 minutes. Construction joints must be keyed, keyed-and-tied, or doweled or reinforced butt joints as specified.

Keyways must be trapezoidal or rounded. Dowels must be 16mm diameter x 300mm length plain round mild steel dowels that comply with SANS 920, or as specified, placed at mid-depth of the slab at 300mm spacings. Coat dowels for two-thirds of their length with a bond-breaking compound. Coat the joint face of keyways with a suitable debonding agent like lime wash or bitumen. Round off all construction joint edges to a radius of 3mm.

• Isolation or movement joints: Form isolation joints where floors abut any fixed structure like walls, columns, sumps or inspection chambers, with 20 mm thick compressible material like polystyrene or bitumen-impregnated softboard. Seal joints only when and as specified, otherwise leave joints open. Seal joints with a suitable elastomeric material as described under WATERPROOFING. Ream sawn joints to width and depth as specified and according to the sealant manufacturer’s instructions.

Reinforced concrete lintels Use grade 20 concrete. Cast lintels in situ or precast and place.

Cast lintels to full width of wall and 200mm longer on each end of width of opening to be spanned, or as specified, and to the following depths and reinforcement:

Clear or daylight span

Depth of reinforced concrete lintel

Mild steel reinforcement

40mm from bottom, for each half brick width of soffit

<1m 1 block or 3 brick courses or 200 mm minimum

None

1 - 1.5m 1 block or 3 brick courses or 200mm minimum

One 12 mm diameter

1.5 - 2m 2 blocks or 4 brick courses or 300mm minimum

One 16mm diameter

>2m As specified As specified

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02.2.4 Precast concrete

Materials Materials, moulds and curing must be as described under

CONCRETE.

Casting Precast concrete or terrazzo units must be prepared by specialist contractors according to SANS 1200 GE: Precast Concrete for Building Work. Units may be cast on or off site in approved conditions.

Arrange a meeting between the specialist contractor and the architect/principal agent well in advance to discuss every aspect of the work, including colour, texture, surface finishes, angles, reinforcement, concrete cover and handling.

Sizes specified are approximate. The contractor is responsible for ascertaining the exact sizes of units.

Steel reinforcement bars or mesh must be as described under

CONCRETE.

Fibre reinforcement must be natural or synthetic of type, diameter and length, relative density and tensile strength as specified. Mix fibres by volume as designed by a Competent Person.

Patents Where relevant, exempt the employer of any claims for infringement of patent rights, design or trade names regarding precast systems used in this work. Pay all due patent holder’s monies.

Samples Submit samples on site of every required architectural finish for approval. Do not start production/place orders before samples have been approved.

Marking Mark every unit indelibly so as to identify its location.

Storing and curing Store units separately on their designed end bearing surfaces in the position they will adopt when built in. Cure for at least 10 days.

Handling Handle units so that strain, deformation and damage is kept to a minimum.

Damaged units Report minor and hair cracks. Repair of these defects may be permitted depending on exposure.

Building in precast units Build in units not before 21 days after casting. Bed and joint units solidly in 1:3 cement:sand mortar. Key joints and tint if necessary to match other facings.

02.2.5 Masonry

02.2.5.1 Bricks and blocks

Clay bricks Use clay bricks complying with SANS 227:

• face bricks of class FBS, FBX or FBA, solid or hollow, as specified;

uniformity of colour and texture is required

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• common bricks of class NFP for general building work

• common bricks of class NFX for general building work, but extra durable

• grade of efflorescence: normal grade for internal walls that will not become damp; special grade for visible unplastered foundation walls, retaining walls or free-standing walls

• water absorption limits of 6-14%

• irreversible moisture expansion of not more than 0,20 %

• work size as specified.

Compressive strength Minimum average compressive strength of masonry units must comply with the minimum requirements of SANS 10400-K provided that the minimum compressive strengths are 3(5)MPa for single storey construction and for cladding and internal walls in concrete framed construction; 7(10)MPa for double storey structural walls, free-standing walls and retaining walls - the number referring to hollow units, the number in brackets to solid units.

Stone Use stone of type as specified, from an approved quarry, and to approved samples.

Proof of quality Ensure that despatch or consignment notes of bricks and blocks delivered to site state the specified requirements. Keep all notes and produce when requested by the architect/principal agent.

Samples Supply a sample of 20 clay face bricks (10 of which are to be retained by the purchaser and 10 by the manufacturer) and six of every other type of clay brick for approval. Keep these units on site for reference.

Storage Ensure that bricks and blocks are carefully unloaded to prevent chipping and breakage. Stack on prepared level areas. Protect from staining or marking.

Reinforcement Wire brick reinforcement must be of hard drawn mild steel comprising two 2,8 mm diameter main wires spaced 75mm apart and 2,5mm cross wires spaced at not exceeding 300mm, welded to main wires.

Steel bars for reinforcement of lintels must comply with SANS 920, of nominal size as specified.

Wall ties must be galvanized mild steel wire or strip wall ties complying with SANS 28, of type and length as specified.

Lintels Use precast prestressed concrete lintels complying with SANS 1504, of sizes as specified. Exposed lintels are to be of uniform colour and without imperfections.

Lintels for exposed work must be uniform in colour and texture, and free from imperfections.

Lay lintels with a bearing length of at least 200mm in 1:5 cement mortar. Prop lintels at 1,5m centers for at least seven days after masonry was completed.

Cut faces of lintels above reveals to make provision for face brick faggots when used in face brick walls.

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02.2.5.2 Mortar

Cement Use common cement complying with SANS 50197, strength class 32,5N or, where available, or masonry cement complying with SANS 50413, strength class 22,5X.

Type, composition and strength of the cement must be shown on the bag or the delivery slip of bulk cement. Bags must be SABS-mark bearing.

Keep bagged cement in a dry store. Always use the oldest cement first. Do not use bagged cement with lumps that cannot be crumbled by hand.

Sand Use natural pit sand for mortar complying with SANS 1090. Supply grading test results if required by the architect/principal agent.

Supply a sample of sand before ordering and make up a small batch to test its workability.

Obtain sand from one source throughout the duration of the works.

Store sand in a way that will avoid contamination by foreign matter.

Lime If sand lacks fine material or is single-sized, use a maximum of 40 liters of building lime complying with SANS 523 per 50kg of cement to improve workability, if required. Do not use lime with masonry cement.

Mixing Mix ingredients dry on a clean surface or by means of a mechanical mixer. Mix thoroughly until colour is uniform. Add water to give the desired plasticity. Use within 2 hours.

Mix proportions Use the following mix proportions for cement:sand mortars:

Class MPa Application Cement:sand

(common cement)

Cement:sand (Masonry cement)

I 10 High-strength structural work (multi-storey, loadbearing)

1:4 or 50kg to 130 liters

1:3 or 50 kg to 100 liters

II 5 Normal loadbearing work, parapets, balustrades, retaining structures, freestanding walls, and walls exposed to dampness.

1:6 or 50kg to 200 liters

1:5 or 50 kg to 170 liters

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Class MPa Application Cement:sand

(common cement)

Cement:sand (Masonry cement)

III 1.5 Unexposed single-storey non-loadbearing walls.

1:9 or 50 kg to 300 liters

1:6 or 50 kg to 200 liters

02.2.5.3 Masonry walling

Bond Use full bricks or blocks wherever possible.

Build half brick walls in stretcher bond, reinforced with wire reinforcement every eight courses. Build one and one-and-a-half brick walls in stretcher bond.