Working with a Structural Engineer

One key person in making sure your design works – and the house doesn’t come tumbling down – is the Structural Engineer. They usually work closely with your architect, and you may not even contact them separately if the architect is handling everything. But in many cases, especially when you’re not using an architect, you will need to talk to a structural engineer directly to make sure you keep the structural integrity of the house by inserting beams when removing a wall or changing the layout significantly. I spoke with Mark Mawby, a structural engineer based in London, for some more insight into his profession.

Why are structural engineers needed?

At the end of the day, we make sure the building doesn’t fall down. We work with architects to come up with a scheme that is pragmatic and suits the building layout, type, nature. We get a feel for the architect’s vision and say well, we can’t do exactly what you want but we can do something close to it if we make these changes and suggestions. Some architects are receptive to that and some just treat the engineer like a calculator – tell me where to put the beams and that’s it.

What’s the right order – Architect first or Structural Engineer First?

It varies – Some clients bring us in very early to find out the feasibility of opening a wall or changing a roof. But a lot of engineers can be a little rigid and only focus on the difficulties and be quite negative.
It’s good to have an architect’s opinion early, so they can come up with creative ideas and identify opportunities – but don’t let them get too far down the road with coming up with designs until you have a structural engineer on board.
If you first identify the schemes, ideas, concepts, opportunities, then get an engineer on board and they can look at the building and go through what might be easier to do and go through the pros and cons, it’s more useful as a sequence of work. As the client, you can get excited about the options and possibilities, and when the engineer comes on board they have enough information to give their input on what is realistic.

Do you need an architect? 

You need to have an architect to get through building control for a lot of projects, especially extensions. But I think it’s the concepts, the coming up with ideas, that trigger other things later. And maybe you just have the architect at the beginning. Understand what you want from your architect and how you are going to work with them. Some only want to do the design, some will do everything it takes to see it through to the finish.

How do you find a good structural engineer? What separates a good structural engineer from a bad one? 

It’s a difficult thing to define because there are different types of firms. For us, we’re very architecturally minded, we like working with architects and helping them do interesting things, it’s more fun that way. Others are more price-driven, they just want to churn out the projects, and aren’t really interested in getting into the iterations. That’s the kind of feel you need to get. If you’re doing an interesting project and you need the architect to be well supported, you should talk to the structural engineer and understand what level of service they’re going to give.  
We price for a lot of jobs and if someone just is looking at the price then we will lose every time to a one-man-band firm that just does the basics – they’ll design a beam as well as we will, but they’re not interested in the ongoing, evolving projects, or being there when the job gets on site. So you need to understand the level of involvement that the engineer is going to provide.

For example, we’re putting a bid in for a basement project and I know how tricky it’s going to be – bad ground, high water table, neighbours objections will need lots of information, and another structural engineer came in at half the price. And I know what they do because I check their work sometimes – and they don’t do the same service. Yes, they’ll design the building and it won’t fall down but you’re not going to get the level of involvement that we will give for the price. You have to know what you’re getting for your money.

We worked with another architect in North London who do all their designs in 3D and they’ll do some very expensive designs too, but the costs of the design process can be very, very high, which means in a lot of those projects the client won’t continue with the architect through the process and we’ll sometimes get a call from the client because it looks a bit weird, and it turns out of course that the builder didn’t really understand the drawings. It’s often hard for clients to spend money at the beginning of a project – usually they are happy to spend money on the things you see at the end like fittings and furnishings! But investing in the architecture, engineering, and build quality can make a big difference.

How does the design process work with the structural engineer for something that is a higher spec or more unusual, for example, the Wandsworth project?

That was actually one of our easiest projects to do, I did that myself with just some hand sketches.  Structurally it was very simple. We had a concept from the arch, he had an idea of what he wanted, and he based his recommendation for the client on what we did for him. Our concepts and view of what was necessary = and what wasn’t – created a fantastic result and it didn’t need to be more complicated.
The art of engineering is creating the elegance of a structure that complements the architecture. If a building looks simple, if we can design it simply, it makes it cheaper to build.
The best results come from a two-way flow of information between the architect/engineer.

Any other top tips? 

• Get an engineer involved reasonably early to temper the architect’s ideas with reality and help give a sense of budgets
• On the flip side, you don’t want to know too much and get scared – need a little naivete!
• Use findanengineer.com to make sure you get a Chartered Structural Engineer.
• At the end of the day, you get what you pay for in life, and that goes for structural engineers as well.
• Building Control approval – I recommend using the Local Authority if you can rather than Independent Approved Inspectors (found at https://www.labc.co.uk/). A lot of clients are going with the independent inspectors because they think they’re cheaper, but you’re not going to get the same level of service. They make sure the building itself is sound- plumbing, drainage, waterproofing, etc. Most large projects will need full plans approval and having someone reputable and sensible through the approval process really helps.