THE TRJ JOURNAL · Granny annexes

Annexes for Family Living

By Constantin Tiseanu · · 3 min read

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Key Benefits of Living in a Granny Annexe

As the UK housing market continues to evolve, more homeowners are turning to annexe living as a practical, cost-effective alternative. In a climate of rising property prices, economic uncertainty, and increasing demand for multi-generational living solutions, a granny annexe presents an ideal way to create additional living space without the need to relocate.

But what exactly is an annexe, and why is it becoming a popular choice for UK families?

What Is an Annexe?

         An annexe is a self-contained living unit located on the same property as the main home. Whether built as an extension or a separate outbuilding, it typically includes a kitchen, bathroom, bedroom, and living area. Often referred to as a granny annexe, this type of accommodation is commonly used to house elderly relatives—offering them independence while keeping them close for family support.

Annexes are also ideal for young adults, guests, or even as potential rental spaces (subject to local regulations), making them a flexible investment.

How the UK Housing Market Is Driving Demand for Annexes

The UK’s property market has faced numerous hurdles—soaring house prices, unaffordable rents, and limited housing availability. These challenges have prompted families to explore alternative living arrangements that offer long-term affordability and convenience.

Adding an annexe allows homeowners to:

  • Maximise the use of their land
  • Avoid costly home moves or major renovations
  • Create a tailored space for changing family needs

Key Benefits of Living in a Granny Annexe

1. Financial Efficiency

Building an annexe can be significantly more cost-effective than buying a new property or renting a separate flat. It provides a budget-friendly way to expand your living space without sacrificing comfort or privacy.

2. Multi-Generational Living

As care home fees climb and families prioritise staying connected, annexes allow elderly parents to live independently while receiving support from loved ones. This arrangement strengthens family bonds and offers peace of mind.

3. Independence and Privacy

Annexes offer a perfect balance—residents enjoy privacy in a fully functional living space, while still being close to the main household. This is especially beneficial for young adults seeking independence or retirees wanting their own space.

4. Increase in Property Value

A well-designed annexe can enhance your property’s resale value and market appeal. Buyers are increasingly seeking homes with flexible living options, and an annexe can be a strong selling point.

5. Energy Efficiency and Sustainability

Modern annexes are often built with sustainable features such as solar panels, energy-efficient insulation, and smart heating systems. These eco-conscious additions not only reduce environmental impact but also lower monthly utility costs.

Economic Pressures Are Shaping Housing Choices

With inflation, rising energy bills, and job insecurity affecting many UK households, families are rethinking traditional living arrangements. An annexe offers a sustainable way to reduce living expenses while adapting to current economic realities.

The planning route remains site- and use-specific. Do not assume streamlined approval or changed rights without an identified applicable policy.

Final Thoughts: Is an Annexe Right for You?

Whether you're planning to accommodate an ageing parent, support a growing family, or simply want to enhance your property’s functionality, an annexe offers a smart, future-proof solution.

In today’s economy, annexes represent not just a lifestyle choice, but a strategic investment in your home’s long-term value and usability.

Ready to Explore the Possibilities?

If you're considering building an annexe, our team of experts is here to help. From initial planning to custom design, we’ll guide you through the process to create a self-contained living space that meets your family’s needs.

Contact us today to learn how a granny annexe could be the perfect solution for your home and future.

Sources and project-specific guidance

Check the current guidance and the actual project specification. Performance, cost and approval depend on the complete design and site.

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PLAN YOUR BUILD WITH TRJ

What should you know before choosing a garden room or annexe?

TRJ Construction Ltd designs and builds SIP garden rooms, granny annexes and house extensions. We work across Hertfordshire, North London, Essex, Buckinghamshire and surrounding areas. The right specification starts with how you will use the building, the site conditions and the services it needs. A home office, a gym and an annexe for independent living have different requirements.

Which type of building suits your project?

Choose the building around its intended use. A garden room can provide a separate place to work, exercise or relax. An annexe needs a layout and facilities suitable for its proposed residential use. A house extension changes the existing home and needs its structure and services considered together.

Compare the main TRJ building options
BuildingTypical useKey decisions
Garden roomOffice, gym, studio or family spaceFloor loading, glazing, heating and any bathroom facilities
Granny annexeIndependent living spaceKitchen, bathroom, accessibility, services and planning status
House extensionAdditional space connected to the homeExisting structure, openings, roof design and building control

What SIP specification does TRJ use?

Our published specification includes 125 mm structural insulated wall panels and 150 mm SIP panels for roofs and bases. The final design must account for the particular building, structural loads, moisture control, ventilation and finishes. Panel thickness alone does not establish the performance of the completed building.

  • 125 mm: the wall-panel specification described in our company information.
  • 150 mm: the roof and base panel specification described there.
  • Since 2012: TRJ Construction Ltd has been led by Costi Tiseanu, whose construction experience spans more than 25 years.

Read Costi’s experience and TRJ’s specification, or see how our buildings are constructed. These are details about our work, rather than industry-wide performance claims.

How do you start a garden-building project?

  1. Describe the use. Tell us whether the building is for work, exercise, hobbies or living accommodation.
  2. Share the site information. Send photographs, approximate dimensions, access details and any existing drawings.
  3. Review the requirements. Discuss planning, building control, foundations, drainage and electrical connections.
  4. Agree the specification. Confirm the layout, materials, fit-out and the items included in the quotation before work begins.

Our completed projects show real examples. Where a project was built by TRJ for Garden Spaces, the case study identifies that relationship.

What questions do clients ask?

Can a garden room be used all year round?

Yes, a garden room can be designed for year-round use. The specification needs suitable insulation, heating, ventilation and moisture control. We discuss the intended use and site conditions before agreeing the build.

Can TRJ include a bathroom or kitchenette?

Yes. TRJ builds garden rooms and annexes with bathrooms and kitchen facilities. The layout, drainage route, water supply, electrical requirements and applicable approvals need to be assessed for the site.

Does every garden room need planning permission?

No single answer applies to every site. Some outbuildings may qualify as permitted development, subject to limits and conditions. Location, dimensions, previous permissions and intended use matter. Living accommodation needs particular care. Check the proposal with the local planning authority before building.

How much will my building cost?

The price depends on floor area, access, foundations, glazing, services and interior finishes. Use our annexe cost guide as a starting point, then request a quotation for your site and agreed specification.

Explore annexe costs · View rooms with bathrooms · Discuss your project