1.1 Documentation of External Works Elements

External works are all the construction work outside the external walls of a building but within the site boundary: roads and parking, paths and paved areas, surface water and foul drainage, fencing and gates, retaining walls, and landscaping. Before they can be measured and priced, each element must be identified from the drawings and the site, described fully and listed in an orderly way, so that nothing is missed when taking off quantities. Good documentation follows the order and rules of the standard method of measurement in use, which in Kenya is the Standard Method of Measurement of Building Works for East Africa for building projects, and the civil engineering method or road specifications for larger civil works. Example: the quantity surveyor on a Kenya Urban Roads Authority non-motorised transport project in Nyahururu first lists every footpath, kerb, drain and tree pit from the drawings before measuring any of them.

1.1.1 Identifying external works like paving, drainage, and landscaping

The first step is to identify every external element from the contract documents and the site, and group them so they can be measured in a logical order.

Sources of information

• Site layout plan: Positions of buildings, roads, parking, paths and boundaries.
• External works drawings: Pavement details, kerb sections, drainage layouts, manhole schedules, fencing details.
• Landscape drawings: Planting plans, grassed areas, trees, retaining walls and steps.
• Levels and survey drawings: Existing and proposed ground levels for excavation and filling.
• Specifications: Materials, workmanship and thicknesses of layers.
• Site visit: Existing features, trees to be removed, ground conditions and access.

Main groups of external works

1.1.2 Walkways

Walkways are footpaths and paved pedestrian areas that link buildings, gates and parking. They are documented by type of construction, width, layers and edging.

• Types: Precast concrete block paving (cabro), in-situ concrete, precast concrete slabs, natural stone, murram or gravel paths.
• Layer build-up: Excavation, compacted subgrade, sub-base (hardcore or gravel), bedding sand, wearing surface.
• Edging: Precast concrete kerbs or edging blocks on concrete haunching, to hold the paving in place.
• Details to record: Width, length along the centre line, thickness of each layer, falls for drainage, edge details, ramps and steps for accessibility.

1.1.3 Drainage systems

External drainage removes surface water and foul water from the site. Each system is documented separately, from the building to the outfall.

• Surface water drainage: Open channels and side drains, gullies, pipes, culverts, soakaways and outfalls.
• Foul drainage: Pipes from the building to inspection chambers, manholes, septic tanks or the public sewer connection.
• Manholes and inspection chambers: Numbered on the drawing, with internal size, depth (cover level minus invert level), cover type and benching.
• Pipes: Material (uPVC, concrete, clay), diameter, length between manholes, gradient and bedding.
• Details to record: The run reference (for example MH1 to MH2), invert and cover levels, pipe size and type, and any special fittings.

1.1.4 Landscaping features

Soft landscaping is the living part of the external works.

• Topsoil: Stripping and storing existing topsoil, and spreading it to a stated thickness over areas to be grassed or planted.
• Grassing: Seeding, turfing or planting grass runners (for example Kikuyu or Paspalum grass) to areas.
• Trees and shrubs: Species, size at planting, pit size, staking and protection.
• Flower beds and hedges: Preparation, planting and mulching.
• Maintenance period: Watering and replacement of failed plants until handover.

1.1.5 Documenting external elements as per requirement

Each identified element is documented in a form that allows accurate measurement and pricing.

1. Take a list (schedule) of elements: Group them in the order of the standard method (site works, roads and paths, drainage, landscaping, fencing).
2. Reference each element: Use the drawing numbers and labels (for example "Path type P1", "MH3 to MH4").
3. Describe each element fully: Materials, sizes, thicknesses, finishes and location, as the standard method requires for its description.
4. Note measurement units: Area, length, volume or number for each item (see topic 1.2).
5. Record queries: Missing or conflicting information is listed for the designer to answer.
6. Prepare sketches: Simple dimensioned sketches of complicated areas help later checking.

1.1.6 Recording structural landscaping elements

Structural (hard) landscaping elements are built structures in the landscape, measured largely like building work.

• Retaining walls: Record length, height, thickness, foundation size, material (masonry, reinforced concrete, gabions), weep holes and backfill.
• Steps and ramps: Number of steps, riser and tread sizes, width, construction and handrails.
• Planters and raised beds: Wall dimensions, lining, drainage layer and fill.
• Pergolas and shade structures: Posts, beams, foundations and finishes.
• Garden and boundary walls: Length, height, thickness, copings, piers and footings.
• Recording method: Each element is described with its dimensions on the take-off list and cross-referenced to its detail drawing, so that excavation, concrete, reinforcement, masonry and finishes can be measured separately.