If you’re planning a house extension, one of the first questions you might ask is, how much will the design cost? While much focus is placed on the construction budget (see our extension cost calculator here), understanding the cost of the design phase is just as important. This article will break down the costs involved in hiring an architect, getting the necessary drawings, and whether a design and build company is a good option instead.
Image above by Matthew, architect in North London on Design for Me. See his full profile and shortlist him for your home project.
How Much Do Architects Charge?
Architects’ fees can vary depending on several factors, such as the size and complexity of your project. As a rough guideline for a private residential project, architects typically charge between 10-15% of the total project cost for full services.
These fees are usually broken down into different project stages, and some homeowner decide to only use architect for the first one or two stages, depending on the complexity of the project and the ability of the builder to take on a design element and liability themselves. The typical breakdown of costs includes:
Outline Design / Planning Drawings – 35%,
Detailed Design / Construction Drawings – 35%
Architect’s involvement during Construction Phase – 30%
If you are looking for more cost-effective solutions, hiring a freelance architect or a smaller firm could help reduce costs, as they often have lower overheads. More details on these costs can be found here.
Planning Application Cost
If your extension requires planning permission, you’ll need to budget for planning application fees. In England, from December 2023, the cost of a householder planning application is £258. Additional costs may apply if you need a Certificate of Lawful Development or if your property is in a conservation area. If your project is more complex, you may need to pay for additional reports such as:
- Structural calculations
- Drainage surveys
- Heritage or environmental assessments (if applicable)
More details on planning application costs can be found here.
Do I Need an Architect?
For straightforward extensions, you may not legally need an architect. However, an architect or design professional can help maximise space, ensure compliance with planning laws, and avoid costly mistakes.
Even for simple projects, having a professional involved can significantly improve the end result, providing advice on materials, cost savings, and ensuring everything meets building regulations. Without an architect, you may end up with unexpected delays or costs due to planning rejections or disputes with your builder.
Read more about hiring an architect here.
Do I Need Drawings?
While you might be tempted to skip drawings to save costs, they are crucial for a smooth project. Drawings help with:
- Securing planning approval (if needed)
- Obtaining accurate builder quotes
- Avoiding miscommunication during construction (often leading to increased costs, delays and/or disputes)
Many architects provide different levels of service, from basic planning drawings to fully detailed construction drawings. Having detailed drawings can prevent costly changes during the build process and ensure the final result matches your expectations.
Learn more about the importance of drawings here.
Can I Just Use a Builder Without Drawings?
Some homeowners prefer to go straight to a builder without architectural drawings, but this can be risky. Without proper plans, you may encounter:
- Unclear costs, leading to unexpected budget increases
- Poor design quality, as builders may prioritise cost-saving over aesthetics
- Disputes due to misunderstandings about the scope of work
Additionally, without proper drawings, you may not be able to secure financing from a bank, as lenders often require detailed plans before approving loans. If you are hiring a builder, with or without an architect, make sure you have a contract in place. Read more about builder contracts here.
What is Design and Build?
An alternative to hiring an independent architect is using a design and build company. This means the same company handles both the design and the construction. The main advantages are:
- Faster process with a single point of contact
- Cost certainty as prices are agreed early on
However, the downside is that you may have less design flexibility. The builder’s in-house designer may prioritise cost-efficiency over creativity. Additionally, design and build companies often use standard solutions, which may not be the best for your specific needs. Read more about the pros and cons of design and build here.
Finding an Affordable Architect
Hiring a freelance architect or a small firm can often be the best route for a small project. Smaller practices typically have lower overheads, making them more cost-competitive.
You can find architects on Design for Me, where you’ll be matched with up to three professionals for free. Read more about finding an affordable architect here.
Benefits of Using a Freelance Architect or Small Practice
If you’re concerned about costs but still want high-quality design input, choosing a small architecture firm or freelance architect can be a great option. Benefits include:
- Competitive fees due to lower overheads
- More personalised service
- A strong commitment to your project
- Greater flexibility in design choices compared to larger firms
Read more about the advantages of small architecture firms here.
Final Thoughts
While the cost of designing a house extension varies based on the scope and complexity of your project, investing in proper design work can save you money and stress in the long run. Whether you choose a full-service architect, a design and build firm, or a freelance designer, make sure you get clear, detailed plans and budget accordingly.
Looking for the right architect? Post your project on Design for Me to get matched with experienced professionals today!
Emily Design for Me
Find your perfect design pro within minutes…
Here at Design for Me we match you with the right design professional, from thousands all over the UK. Get quotes & arrange up to three no obligation consultations. And it’s all completely free! Find out more here or get started below…
