Last edited 14 Nov 2016

External works

Contents

[edit] Introduction

The term ‘external works’ describes any works carried out to the external environment of a building project. These can be works to functional as well as aesthetic features.

BRE describe external works as: ‘All items outside the building footprint but inside the site boundary, encompassing wastewater and surface water drains, supply of utilities (e.g. gas, electricity and cabled services), footpaths, and access for vehicles including car parks and hard standings to be found in the vicinity of buildings.’ (Ref: BRE building elements: foundations, basements and external works)

RICSNew Rules of Measurement Part 3 (NRM3) offers guidance on external works which it categorises as:

  • Site preparation works.
  • Roads, paths, pavings and surfacings.
  • Soft landscaping, planting and irrigation systems.
  • Fencing, railings and walls.
  • External fixtures.
  • External drainage.
  • External services.
  • Minor building works and ancillary buildings.

[edit] Site preparation works

Before construction works can begin, the site clearance and preparatory groundworks are generally necessary. This might include.

  • Removal of any vegetation including roots.
  • Leveling of the site to a roughly even gradient, or modelling the site to create a desired form.
  • Setting out and trench lines laid out according to the building footprint.
  • Establishing site offices, welfare facilities, storage, access routes, and so on.

[edit] Roads, paths, pavings, and surfacings

It is common for the external areas around buildings to require hard standing areas and surfacing features for use by workers, pedestrians and vehicles. These might include:

[edit] Soft landscaping, planting and irrigation systems

Softscape or soft landscape includes all types of plant life, from flowers and trees to shrubs and groundcover. It naturally changes and evolves over time, driven by the climate, time of year and other conditions. Careful consideration should be given to the amount of maintenance that these elements will require to stay in good order.

Read more about landscape design here.

Irrigation systems for gardens and external areas can be used to automate the process of watering. The most common forms are a drip irrigation systems that precisely releases water to the roots of plants, and a micro spray system that deliver a fine spray of water over a defined area. The benefit of installing such systems is their efficiency, delivering a water-use reduction of up to 90% compared to a traditional garden hose.

[edit] Fencing, railings and walls

These can be used to stop or cut down any unwanted pedestrian or vehicular access, to provide privacy, to give delineation between areas and so on. They can be low level such as wooden palisade fencing, or high level such as security fencing with concrete or metal posts and wire mesh. Wrought iron fencing can be finished with spikes or pointed designs, and features such as razor wire and anti-climb paints used to reduce scalability.

There may be a requirement for retaining walls to prevent ground slippage or heave.

[edit] External fixtures

These are fixtures that may be installed for functional or aesthetic purposes outside the building. The most common examples include:

[edit] Bollards

Used as an alternative to fencing to restrict vehicular access and as segregation between pedestrians roads.

[edit] Street furniture

This includes benches, bins, cycle stands, tree guards, lighting, signage, and so on. Within a town or city environment the layout and manufacture of these features may be used to create a period theme; for example, cast iron benches in a Victorian theme. Stainless steel or wood may be used in more contemporary or natural designs or to aid durability.

[edit] Shelters

These may be required to enhance external environments. Bespoke shelters are often supplied by manufacturers for a range of purposes, from smoking shelters for office buildings, to cycle shelters, bus shelters, sports shelters and so on.

[edit] External drainage

For more information, see Drainage.

[edit] Foul drainage

Above-ground pipework is referred to as sanitary pipework, whilst underground pipework is referred to as foul drainage and sewers. Both carry the used water from toilets, sinks, basins, baths, showers, bidets, dishwashers and washing machines.

[edit] Surface water drainage

This carries water from rain, condensation and melted snow/ice from structures. The above-ground guttering and rainwater pipes are referred to collectively as roof drainage. The underground pipework is referred to as surface water drains and surface water sewers.

[edit] Sustainable urban drainage systems

Sustainable urban drainage systems (SUDS) are systems designed to efficiently manage the drainage of surface water in the urban environment. They provide an alternative to, or addition to, traditional drainage systems where surface water is drained directly and quickly into underground, piped drainage. SUDS may include; filter strips and drains, swales, permeable surfaces, basins and ponds, underground storage, wetlands and so on.

[edit] External services

External services might include:

  • Water mains supply.
  • Electricity mains supply and distribution.
  • External transformation devices (wind turbines, solar panels, satellite dishes).
  • Gas mains supply.
  • Telecommunications and other communication system connections.
  • Fuel storage and piped distribution systems.
  • External security systems.
  • Site/street lighting systems.
  • Irrigation systems.
  • Local/district heating installations.

Ensuring that utilities are supplied to developments is vitally important, not just for the completed development, but also for the construction process itself. Developers will need to ensure that existing site information is obtained, and surveys carried out to determine the position, extent and capacity of existing services. They will need to agree with the provider, the design of any new infrastructure that is required, who will provide it, who will adopt it, and any charges, as well as the appropriate testing, inspection, certification, connection (or disconnection), installation of meters and so on.

The costs associated with utilities can be significant, both in terms of the initial capital cost of installation (particularly if there is no existing supply or if the existing supply is inadequate) and ongoing bills during operation. It is important therefore to ensure that the best deal is being obtained from providers and that alternative quotes are obtained if possible.

During mobilisation for construction, the contractor will need to arrange for the necessary water, power and telecommunications services to enable the site to function.

[edit] Minor building works and ancillary buildings

There may be a requirement for buildings to serve the site during the course of the construction works that are generally removed upon completion, such as storage facilities, sanitary conveniences, washing facilities, changing rooms and lockers, canteens, site offices and so on.

Minor building works might also include works such as underpinning existing buildings and boundaries, builders work in connection with site services and so on.

[edit] Find out more

[edit] Related articles on Designing Buildings Wiki

External references