Do You Need A Structural Engineer Or A Civil Engineer?

People are often unsure of the difference between these two professions. In short: all structural engineers are civil engineers, but not all civil engineers are structural engineers. Here is which one your project will need.

Structural versus civil engineering

A structural engineer designs the strength and stability of a building, so the structure can carry its loads and resist local environmental conditions. A civil engineer is responsible for the wider site design and infrastructure.

What does a structural engineer do?

Structural engineers choose the right materials for the design and help the contractor solve structural problems. Structural elements include:

• Foundations and retaining walls
• Steel, timber and concrete frames
• Support systems
• Beams, columns and girders
• Wall stability

A developer building an apartment block needs a structural engineer to produce design calculations for building control approval, ideally before construction starts.

Case study: a five-storey block of apartments

A geotechnical engineer oversaw a 1m x 1m trial pit and produced a report, and the structural engineer designed the foundations, which building control approved. When the contractor dug the foundations, an unrecorded manhole chamber was uncovered that could not be removed. The structural engineer designed a bridge over it so the foundations would not load the chamber. This is common when unforeseen pipes or structures are found that cannot be diverted.

What does a civil engineer do?

Civil engineers work on the infrastructure on and around the site, including:

• Roads
• Bridges
• Sewers and drainage

Case study: four houses on a backland site

New homes in an established area can overload drainage and cause flooding. These four houses were reached by a new cul-de-sac. Following soil analysis, the civil engineer designed a resin-bound permeable road surface on suitable foundations, with attenuation tanks beneath to control the flow of rainwater into the local drains.

Typical structural engineering services

• Analysis and design
• New build projects
• Structural assessment of existing buildings
• Underpinning and foundation stabilisation
• Steel, concrete, masonry and timber structures
• Steelwork and reinforced concrete detailing
• Permanent and temporary piling design
• Temporary works design
• Quality control reports and site inspections
• Overseeing structural work on site

Typical civil engineering services

• Drainage design to cope with heavy rainfall and avoid flooding
• Review of existing drainage capacity
• Design of access road substructures
• Bridge design with minimal environmental impact
• Sustainability evaluations, energy assessments and reports
• Specialist studies
• Final certification

So which do you need?

On most developments, the answer is both: a structural engineer for the buildings and a civil engineer for the site infrastructure.