How much to draw up plans for extension

How much to draw up plans for extension


Co-director | Architectural Design Services | Architectural Designer | Highways

Homeowners often consider extending their homes as a way to add value and create more space without the hassle of moving. However, before you can start knocking down walls or building new ones, you need to have house extension plans drawn up. This article will delve into the costs associated with drawing up house extension plans and what factors may influence these costs.

Understanding House Extension Plans

House extension plans are detailed drawings that outline the design of your proposed home extension. These plans are crucial for several reasons. Firstly, they provide a clear vision of what the finished project will look like, allowing homeowners to make informed decisions about the design and layout. Secondly, they are necessary for obtaining planning permission from local authorities. Lastly, they guide builders during construction, ensuring that the project is carried out correctly.

The cost of drawing up house extension plans can vary significantly depending on several factors such as complexity of the design, size of the extension, and professional fees involved.

Professional Fees Involved in Drawing Up House Extension Plans

One significant cost factor when drawing up house extension plans is professional fees. Typically, you would hire an architect or architectural technologist to draw up your plans. Their fees can vary greatly depending on their experience level and reputation.

Architects often charge between 5% – 12% of the total construction cost for their services. For example, if your extension is estimated to cost £100,000 to build, you could expect to pay between £5,000 – £12,000 for an architect’s services.

Architectural technologists or architectural designers may charge less than architects but still offer a high level of expertise in designing extensions. They typically charge a flat fee ranging from £400 – £3,000 depending on the complexity and size of your project.

It’s also worth noting that these professionals often provide more than just drawing services; they can also help with obtaining planning permission, building regulations approval, and even project management during construction.

Complexity and Size of the Extension

The complexity and size of your proposed extension will also significantly impact the cost of drawing up house extension plans. A simple, single-storey extension will typically be less expensive to plan than a complex, multi-storey extension with bespoke features.

For example, a simple rear extension might cost around £2,000 – £2,500 for plans to be drawn up. In contrast, a more complex two-storey extension could cost anywhere from £4,000 – £6,000 for professional design services.

Additional Costs

Besides the costs mentioned above, there may be additional costs involved in drawing up house extension plans. These can include:

1. Planning application fees: Depending on your local authority’s requirements, you may need to pay a fee when submitting your plans for planning permission. This fee can range from £200 – £300.

2. Building regulation fees: Once your plans have been approved by the planning department, they must also comply with building regulations. The cost for this compliance check can range from £200 – £800 depending on the size and complexity of your project.

3. Structural engineer fees: If your design involves significant structural changes (such as removing load-bearing walls), you may need to hire a structural engineer to ensure the design is safe and sound. Their fees typically range from £400 – £500.


Drawing up house extension plans is an essential step in any home improvement project. While it does come at a cost – typically ranging from a few hundred to several thousand pounds – it’s an investment that ensures your project runs smoothly and results in a high-quality finish that adds value to your home.

Remember that while cost is an important consideration when planning an extension, it shouldn’t be the only factor guiding your decisions. The expertise of professionals like architects or architectural technologists can help you avoid costly mistakes and ensure that your extension is a success. So, take your time to find the right professional for your project, and consider their fees as an investment in the quality and success of your home extension.