Granny Annexes: A Comprehensive Introduction

Published: 22 August 2024
Reading Time: 6 minutes 35 seconds

More Families Are Turning to Granny Annexes for Multi-Generational Living

With an increasing number of families seeking ways to support older relatives, the concept of building a granny annexe is gaining popularity. Instead of downsizing to a retirement flat or moving into residential care, many are choosing to utilise the available space in their gardens.

Granny annexes are becoming a popular alternative as they often cost less than purchasing a retirement flat, with its associated ongoing service fees or the monthly costs of living in a care home. Additionally, when it comes time to sell the property, a quality self-contained annexe can add significant value to the home’s selling price.

Building a granny annexe offers an ideal solution for multi-generational living. It allows families to live together and spend time together when they wish, while still maintaining each household’s independence and privacy.

Garden Annexes: Not Just for Grannies

Over the last 15 years, as we’ve explored granny annexe projects on The Garden Room Guide, we’ve observed that these versatile garden homes aren’t just for elderly relatives. Many families are building annexes for younger relatives, providing them with comfortable, independent living spaces while they save money to eventually enter the housing market. We’ve also seen tailor-made annexes designed for disabled family members, enabling them to live independently with the peace of mind that family is just down the garden path. In some cases, young families have created their own living spaces in the gardens of their parents’ homes.

Terminology: Granny Annexe, Garden Annexe, Garden Lodge, or Granny Flat?

Because these buildings serve more than just elderly relatives, companies are increasingly moving away from the term “granny annexe.” You might encounter terms such as garden annexe, granny flat, living annexe, garden lodge, garden studio apartment, or garden house, all referring to similar structures.

You’ll quickly notice that some companies spell “annexe” with an “e” while others prefer “annex” without the “e.” Both spellings are correct, and the choice often comes down to personal preference, the availability of a website URL, or a desire to stand out in search results.

We favour the term “garden living annexe,” but you may also find buildings described as garden accommodation units, garden bungalows, garden apartments, or garden cabins. It’s worth noting that garden rooms differ, as they are generally not designed to meet the regulations required for sleeping accommodation.

Standalone Granny Annexe or Attached to the House?

Most garden annexe buildings are standalone units, positioned away from the main house, often at the end of the garden. This setup defines the space between the two households, giving each its own independence while sharing the garden area.

However, some granny annexe designs can be attached to the main house as an extension. You would typically need to search for a bespoke granny annexe company.

Granny Annexe Sizes: From Garden Bedrooms to 2-Bedroom Garden Homes

The beauty of the garden annexe industry lies in its flexibility—there’s a suitable-sized building for every garden. Options range from compact garden bedrooms with ensuite facilities to larger studio apartments that can be zoned into sleeping and living areas, to more defined one-bedroom layouts. If space permits, you can even create comfortable two-bedroom homes with practical spaces like utility rooms and entrance halls.

Many companies offer standard-sized garden living annexes that can be configured to your requirements. If you work with a bespoke designer, you’ll have even greater flexibility, with the ability to specify millimetre-precise dimensions to maximise your garden space. Bespoke designers can also accommodate irregularly shaped plots, angling the annexe walls to avoid dead space outside and maximise the interior rooms.

You’re not limited to square or rectangular footprints either. Many garden annexe companies offer L-shaped configurations, which can be an efficient use of space, particularly when the floor plan is divided to create multiple rooms. If you pick Irregular Shape Site in the Site Challenges filter of our directory, it will show you examples of irregularly shaped granny annexes.

Granny Annexe Construction

Granny annexes can be constructed using a variety of methods, all designed to create multi-layer structures that offer comfortable living conditions year-round, much like a timber-framed house with a long, low-maintenance lifespan.

Traditional Timber Frames: Some companies use traditional timber framing techniques where insulation fits within the timber framework. These traditional methods are sometimes paired with computer-guided machinery to ensure millimetre-perfect cuts. Structural-grade timbers are used, with some firms utilising Glulam timbers for extra strength, particularly for large spans.
Structural Insulated Panels (SIPs): Other companies use Structural Insulated Panels (SIPs), which are a sandwich of structural board and insulation. SIPs are quick to assemble and create a highly insulated envelope at the core of the multi-layer structure. If you watch TV shows like Grand Designs you will have seen SIPs used on many of the projects.
Light Gauge Steel Frames: Some designers aim to eliminate timber from their garden annexe designs, opting instead for light gauge steel framing systems. As with their timber counterparts, insulation is fitted between the steel framework.
Interlocking Log Cabins: Inspired by Nordic cabins, these annexes are built with thick interlocking timbers. The best designs feature a double skin with insulation between the layers. The exposed wood finish inside the room creates a unique backdrop to your furnishings.

How to Buy a Granny Annexe

There are various ways to purchase a granny annexe:

Architect-Designed and Find a Builder: Some families commission an architect to design the annexe building and then hire local builders to construct it based on the plans.
Pre-Manufactured Kits and Find a Builder: Multi-room living annexes can also be purchased from garden building websites that offer a variety of garden structures, ranging from sheds and summerhouses to multi-room annexes. After selecting and ordering the building—usually with some limited customisation options—it will be delivered in parts. You would then need to hire a local builder to assemble it, as well as engage plumbers and electricians to install the kitchen and bathroom and connect them to the main services. While these buildings may appear to be a more affordable route, you will need to source and manage big-ticket items like the kitchen, bathroom, plumbing, and electrical works.
Garden Annexe Specialists: The most common and recommended option is to work directly with a garden annexe specialist. These companies guide you through the entire process, from obtaining permissions, and undertaking the installation of the building, leaving you with a move-in-ready home. This approach ensures that building your garden home a stress free process, energy-efficient and maximises both space and budget.

Flexible Pre-Designed Annexe or Tailor-Made Annexe?

When purchasing a granny annexe, you can choose between two design approaches:

Pre-Designed Models: Some companies offer a range of pre-designed annexes that you can personalise by choosing the size, room configuration, doors, windows, and finishes.
Bespoke Design: Alternatively, you can work with a bespoke design specialist who tailors the building to your specific requirements. Bespoke design gives you much more control over the building’s aesthetic style and the interior and exterior finishes used.

Just the Building or a Turnkey Service?

When exploring your options, it’s important to understand the different services offered by companies:

Building-Only: Some companies will install the building with interior and exterior finishes and wire the rooms electrically but leave the kitchen and bathroom installation to you. In these cases, you would need to organise tradespeople to connect the building to the mains services.
Turnkey Services: Many granny annexe companies offer turnkey services, handling the entire project from obtaining approval to handing over the keys to a fully functional home. This fully managed approach has many benefits, including the convenience of working with a single company throughout the build. Typically, you are assigned a project manager who ensures that the right people and materials are on-site at the right time.

Two Granny Annexe Approval Routes

Unlike garden rooms, which can often be built under Permitted Development rights, granny annexe projects require formal approval.

There are two routes to gaining approval for your granny annexe:

Full Householder Planning Permission: Combined with Building Control sign-off.
Caravan Act: Building a mobile home under the Caravan Act and obtaining a Lawful Development Certificate.

Annexe companies often have a preferred approval route, but many now offer both options. Don’t assume that the mobile home route limits you to the types of buildings found in holiday parks—specialist garden annexe designers can create stylish, well-specified buildings that comply with the Caravan Act.

Companies offering turnkey services typically handle the approval process as part of their package, either with in-house experts or by working with annexe planning specialists. You can also choose to work directly with these planning specialists.

Experienced Granny Annexe Specialists

The garden annexe market has grown considerably in recent years, attracting many new companies. While many garden room companies now offer annexe designs, it’s important to remember that an annexe is a more complex building with stricter regulations than a garden room. It’s crucial to ensure you’re working with a company that has the experience and in-depth knowledge to bring your project to life. Take time to assess a company’s experience by exploring their past projects—don’t be swayed solely by stylised computer visualisations.

Several annexe companies have show buildings, allowing you to experience the space and inspect the quality of the finishing details. Companies without a show site can often arrange for you to visit one of their completed projects.

Find Your Granny Annexe Specialist

To help you find the right company to bring your granny annexe vision to life, we’ve created a directory tool. Simply select your county, indicate if you have a preference for approval route, and choose any features you’d like your annexe to have. Hit search, and we’ll provide you with the names of companies that specialise in those features and operate in your area, as not all annexe companies offer nationwide service. By clicking through to the company profile page, you’ll find their contact details and examples of how they can implement the features you’re looking for in their designs

Garden Room Directory