Advice from a builder and architect
Finding really good tradespeople can be tricky, but it's worth putting in the groundwork to make the experience of building an extension as smooth as possible.
We've spoken to a builder and an architect to better understand what's involved when it comes to planning a new extension and what key questions you should be thinking about and asking before you instruct anyone and begin a project.
Skip to the bottom of the guide to also find out more about structural surveyors, architectural technologists and party wall surveyors.
How to find a good builder
The best place to start is to try and find someone who has been through the process before and get their recommendations for good local architects, structural engineers and builders.
To make your hunt a little easier, we've asked an architect and a builder what the most important questions are that you should be asking and what to look out for.
Top tips from a builder
Key questions to ask your architect
Depending on the scale of the project, you may wish to involve an architect. There’s no law saying you need to use an architect, even for large renovations and builds, but some people find it easier to have a professional draw up the designs.
Using an architect will generally mean you’ll get a better end result, however their fees are usually around 15%, so you’ll need to factor this into your budget.
Architects are pricey, but if you want a finish that’s professional, sleek and ultimately makes the most of the space you have, then it could be worth the initial spend.
What about structural engineers, architectural technologists and party wall surveyors?
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 and in building and renovation projects will provide specifications and calculations for the design, as well as suggesting building materials.
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.
For a home renovation or inspection you’ll need to hire a structural 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).
When you’re making home improvements that involve the stability of a building you will probably need a structural engineer. This engineer 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.
As with anyone involved in your project, it’s important to make sure your structural engineer has professional indemnity insurance.
You can also use our search tool below to find reliable traders near you. You don't have to be a Which? member to use Which? Trusted Traders.
Do I need a party wall surveyor?
The answer is not necessarily, and it depends on the complexity of your project in relation to the wall and/or the co-operation of your neighbour. Head to our page on and skip to the section on Party Wall Act to find out more.
What are architectural technologists?
Similar to an architect, a chartered architectural technologist is qualiﬁed to offer full architectural design services and lead and manage projects from inception to completion. They specialise in design with knowledge underpinned by building science, engineering and the technology applied to architecture within projects and plays a pivotal role in project and design management and the construction process.
A chartered architectural technologist will come from a BSc(Hons) background and an architect will have a BA(Hons) background. Both disciplines can work on a project from inception through to completion.
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