Structural engineers – what exactly do they do and why do you need one?

What is a structural engineer?

Structural engineer, surveyor, architect – there’s a list of professionals you may need to involve in a big home improvement project. Each has their own area of expertise. Structural engineers, as the title suggests, specialise in the structure of buildings. They do the clever calculations to assess the strength, durability and safety of existing and new buildings.

A structural engineer will often act as a consultant to an architect or building contractor, assessing the structural condition of your home and calculating the load bearings for your project. This includes assessing the ground conditions and if a building is strong enough to take the extra loads. Whether you are building a new kitchen extension or knocking down interior walls you are likely to need to install supporting beams, usually RSJs, to support the ceiling. A structural engineer will advise what size of steel (concrete or timber) beams need to be in place and positioning as well as any column requirements. They help define the building specification.

Structural Engineers
Structural Engineers

When do I need a structural engineer?

Your architect may suggest consulting a structural engineer in the early stages of a project if ground conditions are challenging, for example if your home is built in in a clay soil area (more prone to subsidence) or if the architectural design is pushing the boundaries, such as a seamless glass box extension with no supporting columns. The structural drawings and calculations provided by the engineer will be used by your building contractor too – or should be.

Whether you need a structural engineer or not will depend on your project. Knocking down the dividing wall between the kitchen and dining room to create an open plan layout is a popular project. A structural engineer will be required to advise if the wall is load bearing and what supports need to be put in place to keep your property structurally sound. If you want to build a new extension or convert the loft, garage or basement, a structural engineer will provide calculations for new staircases, roof joists, posts, columns, floors and more.  

Below is a list of projects that typically require the expertise of a structural engineer:

  • Building an extension
  • Converting a loft, basement or garage
  • Knocking down walls to reconfigure the floor plan
  • Removing a chimney breast
  • Adding or altering doors and windows
  • Underpinning floors
  • Installing solar panels

Basically, any work that changes the structure of your home will need building control approval and to obtain this you will need the services of a structural engineer. A set of detailed plans, including the engineer’s technical calculations and drawings, need to be submitted to building control as part of your building regulations application. In some cases, this technical information may also be required to obtain planning permission.

Structural inspections

A chartered surveyor may also recommend a closer inspection of your existing home by a structural engineer if they spot any potential problems, such as sagging ceilings, uneven floors or cracking walls. A structural engineer may carry out a structural inspection, either of the whole property (general structural inspection) or of a particular area (specific structural inspection) 

Expert witness

Chartered structural engineers have the knowledge and experience to act as expert witnesses. For example, if you are in dispute with a neighbour over a structural issue that affects the stability of your home, they can provide an unbiased view and independent report as well as advise you on your possible options.

Finding the right structural engineer

Look for an engineer who is either a member of the Institution of Structural Engineers (IStructE) or the Institution of Civil Engineers (ICE). For a home extension or renovation, it’s best to hire a structural engineer with experience of residential work as opposed to building roads or bridges! If you have an architect on board, they are likely to recommend particular individuals. You can also find structural engineers who cover your local area, obtain their details and compare prices here

Fees

Costs will vary with the size and scope of the project. Simple beam calculations may only cost a few hundred pounds whereas technical information and drawings for a home extension could set you back £1,500-plus.

A structural engineer is likely to play a pivotal role in your home extension project. They are key professionals working alongside architects and surveyors to turn your dream into reality.

 

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