Structural engineers: What they do & when you need one

A structural engineer can play a key part in your home renovation project, when you need a structural inspection and can help when you need an expert on your side. We take a look at when you might need one, what they do and where to find them.

Angela Kerr Director, Editor

What is a structural engineer?

A structural engineer, as the name suggests, is an engineer who specialises in the structure of buildings. They determine the strength and durability of a structure – i.e. a building – and are a key professional in the construction process. They’re able to assess a building’s safety. In building and home renovation projects, they will provide specifications and calculations for the design, as well as suggesting building materials.

How can I find the right structural engineer?

There are many types of structural engineer with experience of working on a huge variety of structures. For a home renovation or inspection you’ll need to hire an engineer with experience of residential work.

Your engineer is likely to be a member of either the Institution of Structural Engineers (IStructE) or the Institution of Civil Engineers (ICE).

You can find structural engineers who cover your local area, obtain their details and quotes with our free tool:

When do I need a structural engineer?

For Renovations

When you’re making home improvements that involve the stability of a building you will probably need a structural engineer. They will provide structural drawings and calculations which will be used by your building contractor and architect during the renovation work.

This information may also need to be provided to Building Control in order to comply with Building Regulations or, depending on the scale of the renovation, to Planning Officials in order to obtain planning permission. 

Projects which often require the services of a structural engineer include:

• Building an extension
• Modifying doors and windows
• Fitting solar panels
• Loft conversions
• Garage conversions
• Removing or modifying internal walls
• Underpinning floors
• Removing a chimney breast

This is not an exhaustive list. As a general rule, anything which changes the structure of the property will need building control approval and to obtain this you’ll need technical information from a structural engineer.

If you are using an architect for your renovation he/she should be able to advise you on whether you need one. If not, your builder should be able to advise.

Most large scale projects will require an architect, to take care of aspects such as aesthetics, energy efficiency and space planning and a structural engineer to handle matters affecting stability.  If you’re unsure check out our Do I need an Architect? guide.

Find and obtain quotes for structural drawings & calculations from local structural engineers now.

For Structural Inspections

If there is a problem with the structure of your property – from signs of subsidence such as movement or cracking walls or sagging ceilings or roofline – you may need a structural inspection.

It could also be that a chartered surveyor you have appointed to conduct a survey of the property you want to buy identifies structural issues and advises you to have a more detailed structural inspection.

Alternatively, you may notice cracks or other causes of concern in your property and want to assess the damage, identifying possible causes and treatment.

 Instantly receive multiple estimates for a Structural Inspection Survey on your property, from Structural Engineers or Building Surveyors in your local area.

For an Expert Witness

You may also need to enlist the services of a structural engineer if you find yourself in a disagreement with another party over a structural matter related to your home. They can provide an unbiased view, in the form of an independent report and advice on your options.

An experienced Chartered Building Surveyor can also act as an Expert Witness. If required, they can provide a report outlining their independent opinions of the matter and, if necessary, will be able to follow this through to a court appearance. Ending up in court is far from ideal and the input of an Expert Witnesses earlier on could help avoid this.

Find and compare estimates from chartered surveyors experienced as expert witnesses. 

How much does a structural engineer cost?

The cost of using a structural engineer will vary considerably depending on the project and what is required. A simple beam design, for example, without a site visit may cost a few hundred pounds, whereas expert witness services will run into thousands.

You can expect to pay around £100-£200 an hour for a structural engineer. Some may charge by the hour, while others will quote you a set cost for a particular job.

The following table gives a rough guide to structural engineer costs:

For an accurate cost, get quotes for a structural inspection, structural calculations or expert witness.

Anything else I should know?

Yes. As with anyone involved in your project, it’s important to make sure your structural engineer has Professional Indemnity insurance.

It’s also important to be clear what services are included in the quote provided by the engineer.  So talk it through carefully and get a break down of costs. For example, if you are engaging their help to produce technical drawings to be submitted to your local Building Control department for approval, check whether site inspections are included and be aware that if further changes are made by you/your architect or builder, there are likely to be additional charges to have the technical calculations and drawings altered.

Be aware that any work you do on your property that alters its appearance from the outside is likely to require Planning Permission from your local council. Any internal works that involve altering the structure of the building will also need Building Regulations approval.