Designing a House Extension with AI: A Collaborative Approach

With artificial intelligence tools now available to everyone, more homeowners are exploring how AI might help them design a house extension. From floor plans to 3D visuals, AI can offer surprisingly helpful early-stage ideas. While this technology can be exciting and accessible, it cannot replace the value of a skilled architect. A good architect is essential for developing the brief, meeting regulations, and managing the planning and construction process effectively.

Here’s how to begin designing a house extension using AI, and where a professional architect makes all the difference.

Step 1: Measure Your Existing House

The first step in any extension project is understanding your home’s layout and dimensions. For AI tools to generate useful output, you need an accurate base plan. There are two main ways to do this:

Option 1: Use LIDAR on an iPhone or iPad Pro

Modern Apple devices equipped with LIDAR (Light Detection and Ranging) can scan your home in 3D. Several apps, such as RoomScan, Polycam, or Magicplan, allow you to capture the layout of a room or an entire house. You can export this as a floor plan or 3D model. These scans serve as the starting point for generating extension options or visuals using AI tools.

Option 2: Manual Measurement

If you don’t have access to LIDAR, you can measure the rooms by hand using a tape measure or a laser measurer. Record room dimensions, ceiling heights, door and window positions, as well as fixed features like boilers, services, or structural walls. Afterward, you will need to draw this up manually in a CAD program or use free tools like SketchUp or Floorplanner before inputting your data into any AI tool.

Step 2: Draw Up Floor Plans and Elevations

Once you have completed the measurements, the next step is to draw your existing house in plan and elevation. These drawings form the base information that both AI tools and human consultants will rely on.

Plans show the layout of each floor from above, while elevations illustrate the outside face of each wall. These drawings are crucial for any planning application or design study. AI tools often require a clean, dimensioned plan to work from. Depending on the platform, you may need to upload your drawing in a specific format (e.g. PDF, DWG, or SVG).

If you're not confident with this step, consider involving a surveyor or architect early on. Inaccurate or poorly drawn base plans can cause problems later.

Step 3: Generate Extension Ideas Using AI Tools

Once your base drawings are prepared, you can explore design ideas with AI-based platforms. Here are a few popular tools homeowners have begun experimenting with:

• HomeDesigns AI: Upload floor plans or photos to receive suggestions for layout changes and extension configurations.

• Interior AI or Reimagine Home: Generate interior visualizations to test different styles and configurations.

• SketchUp with generative design plugins: Use AI to propose massing or space planning options based on your inputs.

  
  

These tools can provide you with:

• 3D visuals of potential extensions

• Alternative layouts based on your room sizes

• Style suggestions for interiors or exteriors

• Solar studies or rough planning feasibility (in some cases)

  
  

While the results can be inspiring, they tend to be conceptual and not tailored to your specific planning authority or technical constraints.

Step 4: Understand the Limitations — and Where Architects Come In

AI is brilliant for generating initial ideas. It can quickly test layouts, create mood boards, and even produce basic 3D visuals. However, this only one small part of what’s involved in a successful home extension.

Here’s why working with an architect remains essential:

1. Forming the Brief Is a Process

From experience, most clients’ briefs evolve significantly when interacting with their architect. What you initially think you need (e.g., “a bigger kitchen”) often expands into deeper questions about how you want to live, what spaces you genuinely use, and what type of home you envision over time.

AI cannot challenge your assumptions or help you uncover what you didn’t know you needed. A good architect can do this and more.

2. Planning and Building Regulations Must Be Met

Even the most attractive AI-generated designs still need to comply with:

• National and local planning policy

• Permitted development rights (if applicable)

• Building Regulations (covering structure, energy, fire, ventilation, access, etc.)

  
  

An architect understands how to design in a way that maximizes your chances of approval while delivering the space you desire. They can also make adjustments if issues arise during consultations with planners or neighbors.

3. Surveys and Specialists May Be Needed

Depending on your property, you may require:

• Input from a structural engineer

• An arboricultural report

• An ecology report

  
  

An architect can manage these relationships, ensuring the right information is integrated into the design.

Final Thoughts: Use AI to Explore, Use an Architect to Deliver

AI design tools are a brilliant way to start exploring your ideas. They can help you visualize your home's potential and inspire you before you even speak to a professional. However, they are merely tools — not designers, planners, or problem-solvers. A qualified architect can elevate your ideas, challenge assumptions, and guide you through the complex process of getting your project built.

That includes helping to form a brief that suits your lifestyle, securing planning permission, and delivering a finished space that is well-built, compliant, and enjoyable to live in.

Thinking about an extension? We’re happy to offer a short discovery call to explore your ideas, whether you’ve sketched something out, played with AI, or are starting from scratch. Get in touch and let’s see what’s possible.