External Works Design

External works or civil engineering design for external areas can often be complex and sensitive. A combination of strength, durability, cost and future flexibility need to be considered. The requirements at different sites are rarely the same and so an external works design always be bespoke. Unfortunately, this is a design element often overlooked or ignored, until it goes wrong.

What not to do

Don’t leave it to the groundworker…

Remember – a builders or contractor’s job is to build from your designs, not to design your work. Unless you have specifically agreed for them to be responsible for “design and build” then assume they don’t have design responsibility, never mind professional designer’s indemnity insurance. If you do ask them to undertake work as design and build, then remember that they will most likely subcontract the design element out. The designer will be working for them, not you. You may well get the minimum reasonable to complete the job, not someone looking after your long term interests or highest quality. If you have a problem with their work over a year later there is likely not much you can do.

What to do

Get a good team together directly employed by you. A Civil Engineer, a landscape or building architect and QS or project manager if its a larger project.

They can use their experience to help guide your project to a successful and cost effective conclusion.

Check that the Civil Engineer has Professional Indemnity Insurance. Ideally at least £250,000 for Civil Design work.

Check who will do the design and what external works experience they have.

Getting a bespoke external design not standard detail

There are many famous examples across the county including Cornmarket Street in Oxford. The lesson which is not always appreciated is that good design is essential for a sucessful project. The potential saving in avoiding obtaining a professional design is minimal against the construction (materials and labour) of repairing or replacing poorly designed highway works.

Good external works design is not simply robust. Reinforced concrete needs joints. These joints can cause crack propagation through slabs placed above. Additionally, it is only a matter of time before the next utility company wants to lay through the street. The reinforced concrete slab then delays them and the public more and when the service is installed, the reinstatement is rarely the same leading to a new permanent weakness.

Good external design therefore considers future needs and makes allowance for.

Our external works experience

We have considerable experience in the external work / civil design of external spaces in relation to water and highway requirement.

This includes several high profile locations including:

  • Westminster Abbey external areas
  • Exeter Cathedral external work design
  • Pedestrian crossing outside the House of Commons (specially removable)
  • Swinford toll bridge resurfacing

Common procurement of external works design packages

We often work with award winning Landscape Architects or Building Architects to deliver a complete external package.

Civil / External Works Engineering Designer – such as Wilsham Consulting

  • Foundation design – formation, capping and subbase etc.
  • Asphalt or pavement design – road base, binder course and surface course design and specification
  • Advice on specialist surfaces, including porous asphalt, pigmented coloured asphalt
  • Inspection during surfacing works
  • Resurfacing contract management
  • Setting out coordinates and existing and proposed spot levels
  • Construction details of kerbs, paving, lining, edging and other external paved areas.
  • Integration with and design of drainage

Landscape Designer – Such as Fabrik, Chris Beardshaw, Robert Myers Associates, Clews Landscape Architecture

  • Visual and concept sketches
  • Planting schemes
  • Plant and soil specification
  • Inspection of planting installation