When to consult a structural engineer

Expert help is essential when undertaking a self build, extension or major renovation project. Few homeowners are able to tackle the design and construction themselves. A structural engineer can play an important part in the process.

Alan Lace-Evans, Technical Director at independent civil engineering  consultancy Perega, explains the benefit of consulting a structural engineer during your project. 

What is a structural engineer?

A structural engineer analyses, designs, plans, and researches structural systems and components to deliver on the overall design objective and cost constraints.

They look at the property’s superstructure, foundations and water drainage systems. So, the primary concern is to deliver the building’s integrity and ensure the occupier’s safety.

Why do you need a structural engineer?

A structural engineer usually becomes involved in a project via the architect. On many Grand Design-type projects, the proposed building needs to fulfil many demands. It is not possible to achieve a good result without their input.

Understanding material performance is a key part of the skillset. Engineers advise on how best to work with everything from steelwork and reinforced concrete to timber, masonry, glass and carbon fibre.

In this way, structural engineers make the design vision a reality within the confines of what’s possible. So, this is why it’s so important to work with a trained professional.

They understand the potential and limitations of specified products, fixtures and fittings. Plus, it is more cost effective to iron out any issues at the planning stage rather than having to backtrack when problems arise over weeks/months of work.

Engineering foundations 

Good foundations take care of the superstructure of the building. Identifying the best type involves looking carefully at the geology of the area. A structural engineer arranges a geotechnical investigation.

This is hugely important to prevent costly problems such as subsidence and flooding. A trial pit goes 1.5m into the ground to find out the lie of the land. Alternatively, a borehole investigates what is necessary for a more complex project. It goes down a lot deeper, to depths of up to 30m.

The process identifies the first point at which there is a suitable bearing strata in the ground. You do not want the house to sit on loose fill or contaminated material. So, a structural engineer’s skillset means it is possible to identify and design a suitable and appropriate foundation at an early stage.

Analysing serious problems

Structural engineers are regularly involved in a substantial amount of remedial work to existing buildings. They mostly deal with subsistence issues or structural failures.

These often arise because an expert was not consulted during the original build. An experienced professional can sidestep such issues, preventing expensive, and highly stressful, problems in the future.

Waste water and rainwater run-off

A structural engineer provides consultancy advice for rainwater run-off from a building and its safe disposal. If living in a region with heavy rainfall you need to incorporate systems to prevent flooding. This may take the form of attenuation tanks or soakaways.

An architect or contractor will want to know how waste water will be disposed of. This could be to a mains drainage system or an on-site sewage treatment tank, if there are no  nearby sewers.

How do I find a structural engineer?

Before you commit your cash, ensure you are dealing with a quality supplier. There are many contractors who claim to offer a one-stop-shop that includes structural engineering services. Employing an independent engineer is preferable as they report directly to the architect and you on structural options. They certify that works have been completed to the correct standards.

So, check individuals are members of the Institution of Structural Engineers. This is a globally recognised institution for the profession and certification confirms that you are working with an expert. The organisation holds a categorised database of its chartered members, helping you locate the right engineer for your requirements.