If you’re planning a self-build, or even a major extension of it, you’ll almost certainly come across the term ‘design and build’. On the face of it it sounds like the obvious solution. One company designs and then builds your project, and with them taking overall responsibility what could go wrong?
Building or renovating a home requires countless decisions, a team of professionals and tradespeople and hundreds of technical details that all have to come together exactly at the right time. The thought of someone else coordinating everything can understandably take a huge weight off your shoulders.
But the reality is that design and build isn’t a standard service. Every company offers something slightly different, and whether it’s the right route depends just as much on the type of person you are and your expectations as it does on the type of project you’re undertaking. Here, I explain what's involved to help you assess if it's the right choice for you.
What is a design and build package?
In its simplest form, a design and build package brings the design and construction of a project under a single contract. Rather than appointing an architect to produce the drawings before finding a builder to price and construct them, you appoint one organisation that takes responsibility for delivering the project from concept through to completion.
This doesn’t necessarily mean that everyone involved works for the same company. Many design and build businesses use independent architects and specialist consultants, as well as independent subcontractors to complete the building work.
A design and build contractor will offer a single point of responsibility, managing the appointments and coordinating the whole design process. From a client’s perspective, this is a big attraction. Instead of trying to coordinate several consultants and contractors yourself, you’re dealing with one organisation that is responsible for bringing everything together.
For many self-builders, particularly those building for the first time, that’s a reassuring prospect. But, it's also not uncommon for some clients to want to be involved in every decision. Others might prefer a hands-off approach and simply want confidence that someone experienced is managing the project properly. Neither approach is right or wrong, and the important thing is to understand what you’re buying before you commit.
How does the design and build process work?
Although every company has its own way of working, the process usually follows a fairly logical sequence. It usually begins with understanding precisely what you’re trying to achieve – the brief.
This should consider much more than just how many bedrooms you want. A good brief should set out how you intend to live in the house, what your priorities are, what your budget is and whether there are any planning constraints that could influence the design.
Once that brief has been established, concept designs are then developed and signed off before progressing to planning drawings which are needed to secure planning permission.
After planning approval has been granted, the next stage, in my experience, makes the biggest difference to how smoothly the build progresses: the technical design. This is where the structural design is coordinated, insulation strategy agreed, drainage layouts designed, and dozens of construction details and technical assessments completed, to prove that the design complies with the building regulations.
Once full building regulations approval has been secured, construction can begin. Throughout the build, the contractor coordinates trades, project manages the programme, oversees quality and health and safety working towards completion of the contract and handover.
It sounds straightforward, but competence, focus and good coordination at every stage is what makes the difference between a project that feels organised and one that constantly seems to be catching up with itself.
How is it different from a traditional route?
The traditional procurement route separates design from construction. You first appoint an architect who then works through the design, obtains planning permission, prepares building regulations drawings and then invites builders to tender for the work.
In theory, this approach gives you control over the design before construction starts. It also means the architect works directly for you rather than the contractor.
The downside is that builders don’t normally become involved until much later in the process, so the first indication of the eventual cost often comes after months of design work has already been completed. If the tenders then come back significantly over budget, the design may need to be revised or, worse still, aborted.
Design and build tries to avoid this by allowing the design and the budget to develop hand in hand. Instead of designing the structure first and pricing later, the project evolves with both cost and design considered alongside each other. This should mean fewer surprises for you.
What is and isn't included?
‘What’s included’ is the question that self-builders should ask more than any other. Unfortunately, people often assume that all design and build packages include the same products and services. They don’t.
One company may provide architectural design, planning, building regulations drawings, structural engineering, project management and construction. Another may only include the architectural drawings and the build itself, leaving you to arrange surveys, planning services, specialist consultants, utility connections or landscaping separately.
Even items such as flooring, decorating, fitted wardrobes, external drainage, driveways or external works can vary between design and build companies, which is why I always recommend asking for a detailed schedule of work, which should explain exactly what is included within the contract.
How are costs calculated?
One of the biggest advantages of a design and build approach is that building costs can often be considered while the design is still developing. If you decide you want larger windows, a vaulted ceiling or a more complex roof, the financial implications can usually be assessed before the drawings are finalised. This helps to keep the project aligned with your budget.
However, it’s important to remember that budget prices are usually based on assumptions, which may change. For example, ground conditions may still be unknown or utility providers may not have confirmed the connection costs.
As more information becomes available, the actual cost will become clear, so always make sure you understand who will be picking up the bill – you or the contractor.
Don’t forget, if you’re dealing with only one design and build contractor their prices might not be exposed to competitor pressure. This might mean that you could be paying too much, so always check for value for money by sourcing a few check prices from alternative suppliers.
Visiting events such as the Homebuilding & Renovating Show can be a good way of doing this as you can talk to a wide range of suppliers and industry experts in person, in one place.
Does it give cost certainty?
This build route certainly has the potential to provide greater cost certainty than some traditional procurement routes, but it doesn’t eliminate financial risk altogether. The reality is that no contractor can accurately price work that hasn’t yet been fully designed.
Likewise, no one can predict every unforeseen issue that might emerge once construction begins. Unexpected ground conditions, changes made by the client, planning requirements and utility company costs can all affect the final account, depending on the terms of the design and build contract.
A good design and build contractor won’t promise that costs can never change. Instead, they’ll explain exactly when the contract sum becomes fixed, what assumptions have been made and how variations will be dealt with if circumstances change.
In my opinion you’ll be far better off by having an honest conversation about what’s included rather than the fixed price, no matter what happens.
How involved will you still be?
One misconception is that design and build allows you to hand over the project completely and just wait for the keys. It doesn’t work like that, however. You’ll still need to make countless decisions throughout the project, particularly where design is concerned or when the contractor proposes something different to what’s in the contract.
When it comes to design and build the difference compared to traditional approaches is that someone else is coordinating the process rather than you having to do it yourself. In many ways that’s what you’re paying for, and good design and build companies will guide their clients through decisions so they’re timely and won’t become delays later.
Does technical design still matter with design and build?
Absolutely. This is probably where there’s the greatest misunderstanding. People sometimes assume that because they’re buying a design and build package, the technical information somehow becomes less important, because the contractor will take care of it.
In reality, technical information is still vital and ultimately will ensure that your finished home is safe, durable and energy-efficient. It’s therefore not something that should be left to the contractor’s discretion.
An important point to note is that building regulations compliance shouldn’t just rely on standard specifications. Drawings and details are also needed to show how the building is intended to perform – for example: how insulation will remain continuous; how thermal bridges are addressed; how cavity barriers will be installed; how moisture will be managed; and how airtightness will be maintained.
Without adequate construction details, contractors are left interpreting general notes, and building control can’t fully assess and check how compliance and quality is achieved. And without the complete information about what’s being built, you’ll have a limited understanding of what you’re getting and how your home will perform.
Are there any drawbacks to design and build?
The benefits of design and build are generally clear. Having one organisation responsible for both the design and construction of the property usually creates better communication and clearer accountability. Problems can often be resolved quickly because there’s less opportunity for disagreements between the design team and the contractor, and cost management is often stronger because construction expertise is influencing the design from an early stage in the process – so what gets designed is usually buildable for the budget.
Many clients also find the process is less stressful because there is one main point of contact throughout the project. However, there are a few trade-offs.
If you feel the need to control everything yourself, or want your architect to remain completely independent from the contractor, the traditional procurement route may suit you better.
There’s also the matter of architectural creativity, as builders aren’t usually valued for their architectural flair. Some bespoke architectural projects will therefore benefit from being fully developed before a contractor is appointed to do the construction.
FAQs
Can you use design and build for extensions and renovations?
While people tend to associate design and build with new-build homes, it works equally well for extensions, loft conversions and comprehensive refurbishments. These projects involve many of the same challenges as new homes and having one organisation managing the professionals and the tradespeople can remove a great deal of stress. For busy, time-poor homeowners, design and build can be an excellent solution.
When are traditional routes better?
If you’re building a highly bespoke home with a strong architectural vision, it’s often better to develop the design independently before appointing a contractor. Experienced self-builders who are happy to manage consultants, control procurement and can thrive in the chaos of a build will find that the traditional route gives them more flexibility, which their project may need.
A well-organised design and build company with experienced designers, good project managers and a commitment to producing properly coordinated technical information can deliver an outstanding project with fewer surprises, better cost control and a smoother construction process.
The key to making it work for your particular project starts with understanding precisely what service is being offered and knowing what’s included. Design and build differs from a custom build package, so my advice is to ask plenty of questions and make sure the technical design is detailed enough to demonstrate not only what is being built, but how it will comply with the building regulations and perform as a residence for decades to come.
Get these fundamentals right and a design and build package can be one of the most effective ways to deliver a successful self-build, extension, renovation or loft conversion.
