Planning a House Extension? Catch up with this article by our very own Managing Director, John Staves in the Autumn Edition of “Your Build” Magazine.

Extension Essentials

If you’re planning to extend your home, there are a few essential steps to keep in mind.  John M Staves, Fellow and Vice President at the Institution of Structural Engineers, shares his top tips on extensions

Property extensions are extremely popular amongst UK homeowners, where the current market trend is to ‘improve not move‘.  While such work will increase floor space and potentially add value, it’s a serious undertaking and should not be taken lightly.

To ensure that your proposed extension goes smoothly, a clear plan is crucial.  You need to understand your motives, so asking yourself plenty of questions from the outset is an important step.  When you have clarified the purpose of the changes and decided your budget, it’s time to consider the plan and draft your timeline.

Develop a Clear Brief

It is time to brief your professional design team.  On a fundamental level, an architect will work on the extension’s layout, the master builder will oversee construction and a structural engineer will make sure alterations can be made safely as well as suggest ways to improve buildability and thereby reduce costs.  Have a clear plan and appoint a design team, including Structural Engineer, at the outset.  Discuss your requirements and expectations in detail.

Client, Architect and Engineer Should Work Collaboratively

The key here is to establish a dialogue between all parties involved, early on in the project.  For instance, the architectural design should not be completed without an engineer, who is then asked to make the design stand up.  This situation will invariably lead to unnecessary structural complexity and cost.  You may consider appointing a practice that handles both architecture and structure internally to ensure collaboration and single supplier responsibility for the outcomes.

Keep You At The Heart of Change

If you intend to remain in the property during the works, it is important that the design takes the necessary work sequence into account.  A good design will do this, as well as making sure that the final layout is that you want, and all are structurally sound.

Time Management

Account for everything, including statutory approvals (planning and building regulations take time).  A simple extension that needs planning approval can easily take six months to design and get approved.  You must ensure that all regulatory criteria are met before the builder prices the detailed design, this will allow them to start work on schedule avoiding significant delays and incurring further costs.

Budget Realistically

For the build and professional fees, it is worth taking the time to establish a sensible and comfortable budget before committing fully to the project.  You want to avoid a disappointing scenario where you have already secured your statutory approvals and completed the design only to find the build cost is unaffordable.

Ultimately, people make mistakes when they rush into the build process without having considered all the various factors, variables and potential outcomes.  Taking a calmer, more measured and holistic approach will allow you to observe the project in its entirety and help you to come to the right decision and deliver the type of extension you want, on time and on budget.

This article first appeared in Autumn’s edition of “Your Build” Magazine.

Extension Planning? Catch up with this article by our very own Managing Director, John Staves in the Refurbishment and Renovation News.

Extension Planning

Property extensions are one of the most common structural improvements undertaken by homeowners, increasing floor space and adding value.

To put it into perspective, in 2018, insurer Hiscox identified a significant increase in the trend for ‘improving not moving‘ over the last decade.

Whether extending to the side, rear or both, it’s a decision which requires careful planning and an awareness of the potential disruption and inconvenience to daily life that such a project will cause.

As such, you need to get your thoughts clear from the outset. All too often, I have seen people rush into this type of build gung-ho, without considering all the variables and potential outcomes. In short, this attitude can lead to costly mistakes.

First Principles

Begin with first principles, questioning the motivation behind the decision to extend:

  • What are you looking to achieve?
  • Why doesn’t the current layout work?
  • Is an extension the best solution?

Sometimes it might be concluded that a small adjustment of the internal layout of the property is all that’s needed, and is certainly more cost effective than an extension.

Clear Brief

Next, before you even engage your suppliers, develop a clear brief, and outline your aims and objectives.

These will act as guidelines to all those who will subsequently be involved in the construction journey. This document will ensure the project stays on track, in line with the original vision throughout.

Engage The Right Professional

Make a list of all the suppliers you might need to consult and identify their potential roles in the process.

One mistake, which can have a big impact down the line lies in the misunderstanding of the roles and responsibilities of the different professions within the construction industry.

For example, I’ve seen chartered surveyors confused with structural engineers.

This resulted in disaster down the line when the homeowner found a major fault in their new extension, something which could have been avoided had the right professional been consulted in the first place.

Check Qualifications

Equally, it’s important to check the qualifications of those you employ. Make sure they are accredited with a professional association such as the Federation of Master Builders (FMB), Institution of Structural Engineers (IStructE) and Royal Institute of British Architects (RIBA).



In the past, I have come across clients who have engaged an inexperienced, unqualified ‘engineer’ and then found problems during construction, which are either design errors or too complex for such an individual to resolve.

Always ask for their experience and any examples of previous work.

Collaboration – Keep Costs Down

Once everyone is on board, it’s important to work collaboratively.

Ongoing dialogue between client, architect, builder and engineer is crucial to success.

For instance, the architectural design drawings should not be completed without an engineer; this avoids the common problem of a scheme which doesn’t work or is physically impractical.

I would advise creating a situation where all parties involved are in constant discussion and ultra-clear on every step of the build process.

This will help prevent any avoidable structural complexity and, subsequently, keep costs down.

Joined Up Approach

One method to deliver this joined-up approach is to appoint a practice which offers both architectural and structural services, streamlining through a single supplier who is responsible for all outcomes.

Create two budgets, one for costs and another for time.

  1. Costs. This will keep your expenditure logged in one place and help to manage everything from builder fees to materials purchased.
  2. Time. Will help with organising the construction journey and improve efficiency.

Factor essentials into this activity schedule, such as planning and building regulations through to the estimated completion date.

To put it into perspective, a simple extension which needs planning approval can easily take six months to design and get approved.

Ultimately, the old principle ‘To fail to plan is to plan to fail”, rings true.

In Summary

Organise yourself, and you will achieve the peace of mind that you’re working with skilled professionals who understand your vision and are equally aware of budgets and timeframes.


IStructE’s Building Confidence

To find out more about the role of a structural engineer and free, practical advice on undertaking a residential extension, visit IStructE’s Building Confidence hub.

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