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How Much Does a Granny Annexe Cost in the UK?

As multigenerational living becomes more common in the UK, the granny annexe is rising in popularity as a flexible, private, and practical solution.

But how much does it really cost to build one—and what are the options, from bespoke brick builds to prefabricated garden pods?

In this guide, we’ll break down the average cost of a granny annexe in the UK, explore what influences the price, and compare a range of options—including how prefabricated solutions like Hully Pods offer a stylish and cost-effective alternative.

TL;DR
  • Average Cost Range:
    Traditional brick-built annexes cost £60,000–£120,000+, while prefab modular options range from £20,000–£70,000. Budget-friendly prefab pods like Hully Pods start at £4,495.
  • Main Cost Factors:
    Size, layout, self-contained features (bathroom, kitchen), insulation, site prep, and planning permissions have the biggest impact on total cost.
  • Planning & Regulations:
    You may need planning permission depending on the annexe type and use. Hiring a consultant costs £500–£2,000.
  • Hidden Costs:
    Include foundations (£3k–£10k), utility connections, insulation upgrades, delivery challenges, and certification fees.
  • Prefab Example – Hully Pods:
    Compact, insulated, and energy-efficient pods (e.g., Skipjack from £4,495, Schooner from £6,895) offer quick installation, minimal planning, and modern designs.
  • Best Value Insight:
    For families needing affordable extra living space—especially for relatives or home offices—prefab pods provide the best value versus full extensions or conversions.

What Is a Granny Annexe?

A granny annexe is a self-contained living space built within the grounds of a main property—usually designed for elderly family members, adult children, or as guest accommodation.

It typically includes a bedroom, bathroom, living area, and sometimes a kitchenette.

Annexes can be attached to the main house, converted from existing structures, or built as freestanding garden buildings.

Granny Annexe in the UK

How Much Does a Granny Annexe Cost in the UK (2025)?

The cost varies based on the build type, size, and internal spec. Here’s a breakdown of the typical price ranges:

Type of Annexe

Typical Cost Range

Details

Traditional Brick-Built Annexe

£60,000 – £120,000+

Custom-built, often with planning and building control, high labour costs.

Garage Conversion or Loft Conversion

£25,000 – £60,000

Utilises existing space; costs depend on layout and structure.

Modular or Prefabricated Garden Building

£20,000 – £70,000

Delivered to site and assembled, faster build times, varying specs.

Hully Pods (Prefab Pods)

From £4,495 to £9,295

Cost-effective, stylish, plug-and-play pods with optional electrics, solar.

Prefabricated granny annexes offer one of the best value-for-money options, especially where space, time, and budget are limited.

What Affects the Cost of a Granny Annexe?

Several factors will influence your final cost:

1. Size & Layout

Naturally, larger spaces cost more to build. A compact pod with one room is far more affordable than a multi-room extension.

2. Self-Contained Features

Adding a bathroom or kitchen adds to both materials and utility connection costs. Plumbing and drainage are key price drivers.

3. Interior Finish & Insulation

From basic cladding to underfloor heating and energy-efficient glass, your interior choices can add £5,000–£20,000 depending on spec.

4. Planning & Regulations

Depending on use and structure, you might need planning permission. Hiring a planning consultant could cost between £500–£2,000.

5. Site Prep & Groundworks

Foundations, access, drainage, and utility routing can add significant costs—typically £3,000–£10,000 depending on the site.

granny annexe solution in uk

Real-World Example: Hully Pods as a Cost-Effective Annexe Solution

Hully Pods offers a range of prefabricated, stylish garden pods that work as compact granny annexes—perfect for short- or long-term accommodation without the time or budget of a traditional extension.

Example: Skipjack Pod – From £4,495

  • Internal dimensions: 2.3m x 2.2m x 2.6m
  • Ideal for single-room accommodation or as a guest suite.
  • Add optional electrics, solar panels, or interior upgrades.
  • View Skipjack Pods →

Example: Schooner Pod – From £6,895

  • Internal dimensions: 2.3m x 2.2m x 3.8m
  • Offers enough room for lounge/sleep combo or office/living split.
  • Also available in a glass-fronted version for a modern garden look.
  • View Schooner Pods →

These pods offer many of the same comforts as a traditional annexe—insulation, heating, electrics—at a fraction of the cost and with less planning complexity.

Hidden Costs to Be Aware Of

Even with a prefab build, it’s wise to budget for:

  • Foundation/Base Setup: Timber or concrete base prep
  • Utility Connections: Water, power, drainage (may need trenching)
  • Site Access or Delivery Constraints
  • Heating & Insulation Upgrades: Underfloor heating, triple glazing
  • Planning Certificate: (e.g., Certificate of Lawful Development)

How Granny Annexes Compare to Other Space-Saving Options

Option

Best For

Typical Cost

Granny Annexe

Long-term living for elderly/children

£40k–£100k

Garden Office Pod

Work-from-home setup

£5k–£20k

Hully Pod

Flexible living & working space

£4,495–£9,295

Garage Conversion

Retaining value in existing space

£25k–£50k

Loft Conversion

Adding an internal bedroom

£30k–£60k

granny annexe vs other uk

Conclusion: What’s the Best Value for Your Needs?

If you’re looking for a fast, flexible, and budget-friendly way to add liveable space to your home, prefabricated options like Hully Pods offer excellent value.

With models starting from under £5,000, they’re ideal for:

  • Elderly relatives needing privacy and proximity
  • Adult children returning home
  • Guest spaces or part-time rentals
  • Home studios or remote workspaces

Before committing to a major extension or full build, it’s worth comparing pod options. Visit our Pod Price & Size Comparison Page to explore what’s possible for your garden—and your budget.

Next Steps

Got a question about pod delivery, planning, or installation?
Speak to the Hully Pods team—we’ll help you explore what’s possible based on your garden layout and needs.

Kianna Harrison Hully Pods

Kianna Harrison

Kianna is the engine room of Hully Pods. From coordinating deliveries and managing stock to advising on Pod décor and collaborating on marketing campaigns—Kianna does it all. With an encyclopaedic knowledge of what each Pod is made from and how it’s built, she ensures every part of the business runs smoothly. If you’ve got a question about Hully Pods, chances are Kianna has the answer.