Cost of Architectural Services for an Extension

A Guide to Architectural Service Costs for an Extension

Use this guide to get a better idea of the cost of architectural services for your extension. Find out how the size and scope of your project will affect costs, as well as some top cost-saving tips to help you make the most of your budget.

We'll cover the following topics in this Price guide:

1. Average architectural service costs for an extension
2. What services do architectural fees include?
3. Small vs large extension architectural costs
4. Top cost-saving tips for architectural services
5. Long-term benefits of hiring an architectural professional
6. Find architectural professionals near you on MyBuilder
7. FAQ: Common questions about extension architect costs

Average Architectural Service Costs for an Extension

Architectural professionals don't just draw up plans; they design spaces that are both functional and beautifully tailored to your lifestyle. From securing planning permission to navigating building regulation costs, they help smooth out the most complex stages of your extension build.

Typically, architectural service fees for extension projects are calculated as a percentage of the overall construction costs, ranging from 7% to 15% for a full service. For drawings only, fees are usually charged as a fixed cost.

Take a look at the average cost of architectural services for an extension by project type:

Extension type	Architectural service costs (full service)
Single-storey extension	£4,000 – £8,000+
Double-storey extension	£6,000 – £12,000+
Loft conversion	£3,000 – £10,000+
Basement extension	£8,000 – £15,000+

Note: VAT is typically added to these fees. Costs above reflect a full design and management service. If you only need planning drawings, expect to pay £1,000 to £2,500 for a single-storey extension, rising to £3,000 if building regulations and construction drawings are included.

Don't forget: To get the best price possible for your extension project, post your job on MyBuilder and connect with multiple verified architectural professionals in your area. You can then discuss the job, get advice, and request quotes.

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What Services Do Architectural Fees Include?

Architectural service fees usually span several stages, each playing a vital role in turning your ideas into a successful build.

During the design stage, your architectural professional develops the core concepts that define how your new space will look and function. Planning fees depend on how detailed the drawings and documentation need to be for approvals and applications.

Take a look at the different services included in the cost of architectural services for an extension:

• Conceptual design: Establishing the initial vision. Cost: £1,000 to £3,000

• Detailed design: Developing precise plans and specifications. Cost: £3,000 to £6,000

• Planning application: Preparing and submitting necessary documents. Cost: £500 to £1,200, depending on complexity and local requirements

• Building regulations drawings: Creating detailed architectural drawings to meet legal standards. Cost: £3,000 to £5,000

Don't forget: The intricacy of the design and choice of materials can substantially influence fees, so discussing these elements with your architectural professional upfront is wise to avoid unexpected costs.

Small vs Large Extension Architectural Costs

The cost of architectural services varies by extension size for several reasons. A larger extension typically requires more comprehensive services, including detailed planning and extended project management.

Take a look at how the size of your extension could affect the cost of architectural services:

Project complexity

Large projects often involve more intricate designs, requiring extensive planning and drawing efforts.

Scope of work

Larger projects require more hours from architectural professionals, which explains the difference in fees.

Design specifications

Customised design features in both small and large projects can increase costs, but their relative impact is greater on smaller extensions.

Duration of project

Longer projects may involve extended site oversight, leading to higher fees for large extensions.

If you want to know how much your extension will cost from start to finish, read this full extension building cost guide too.

Top Cost-Saving Tips for Architectural Services Related to Extensions

Successfully managing the cost of architectural services can significantly impact the total cost of your extension project.

To do this, it's important to be clear about your budget and the work you need done.

Here is how:

• Understand clearly what you need from your architectural professional to tailor your negotiations effectively.
• Request a detailed breakdown of fees to understand each cost component.
• Compare multiple quotes to ensure competitive pricing.
• Ask about discounts or packages for combined services to save costs.
• Consider whether you need a full service or just planning and building regulations drawings, since drawings only can cost significantly less.
• An architectural technologist or designer typically costs 20 to 40% less than a registered architect and is equally well-suited to most straightforward extensions.

MyBuilder Tip: To compare quotes for your project, post your job on MyBuilder today. Architectural professionals near you who are interested in the job can respond, without you having to spend hours searching yourself.

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Long-Term Benefits of Hiring an Architectural Professional

Hiring an architectural professional for your house extension offers lasting benefits.

Their expertise and creativity can elevate your design, ensuring your new space is both practical and in harmony with your existing home.

Here's how an architectural professional can make all the difference:

• Improve your property value: A thoughtful design can make your home more appealing to future buyers.

• Make the space functional: Architectural professionals know how to maximise space and tailor layouts to your lifestyle.

• Create visual harmony: They ensure your extension complements the look and feel of your existing property.

Plus, they'll make sure your plans meet all building regulations, helping you avoid delays, fines, or costly mistakes down the road.

If you want to know more about building regulations, see this full building regulations cost guide here.

Find Architectural Professionals Near You on MyBuilder

Planning a home extension and want to understand the cost of architectural services? Post your project on MyBuilder today.

It's a quick and easy way to connect with local architectural professionals, compare quotes, read customer reviews, and find the right person to bring your ideas to life within your budget.

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FAQs About Architectural Services for Extensions

How Do Architectural Service Costs for an Extension Compare to the Overall Project Cost?

The cost of architectural services for an extension generally represents a percentage of the total project cost, ranging from 7% to 15% for a full service. For smaller or less complex projects where you only need planning drawings, fees are often charged as a fixed cost rather than a percentage.

What Methods Do Architectural Professionals Use to Calculate Their Fees?

Architectural professionals typically use three methods to calculate their fees. These include percentage-based fees relative to the project's overall cost, fixed fees for a defined scope of work, and hourly rates for more flexible arrangements. The chosen method often depends on the project type and the level of service required.

What Additional Costs Should I Budget for Beyond Architectural Fees?

Beyond architectural fees, you may encounter additional costs such as the planning application fee (£528 in England as of 2026), building regulations application fees, a structural engineer assessment, and a measured survey.

Always discuss potential extras with your architectural professional to get a clear picture of the total outlay will be for your extension.

How Does the Complexity of an Extension Impact Architectural Service Costs?

The complexity of an extension significantly impacts the cost of architectural services, as more intricate projects require greater time and expertise. Complex projects may require detailed planning, additional consultations with specialists, and customised solutions. These factors typically translate to higher fees.

A straightforward single-storey extension will generally sit at the lower end of the fee range, while a basement or double-storey extension with bespoke design requirements will sit at the higher end.