A two bedroom granny annexe

Planning for a Granny Annexe in the UK: A Step-by-Step Guide

At Rubicon Garden Rooms, we understand the desire to keep loved ones close. Granny annexes, also known as garden annexes, granny flats etc, offer a fantastic solution for multigenerational living. They provide your family member with independence while ensuring they're just a step away from the security of loved ones.

However, planning and building a granny annexe involves several considerations. This detailed granny annexe guide will walk you through everything you need to know, from legalities to design choices.

Do You Need Planning Permission For A Granny Annexe?

This is a crucial first step. Generally, if you use a traditional build method, granny annexes will require planning permission from your local authority. However, there are some exceptions:

  • Mobile Home Regulations: These allow specific living accommodation without the need for formal planning permission or building regulations. A Rubicon annexe built under the Mobile Homes Act can have the same look and feel as a traditional house extension but they must be:
    • Single storey
    • No higher than 3 metres internally
    • A maximum size of 20m x 6.8m
    • When assembled, be classed as moveable
    • Be fully self contained living accommodation  
    • For the exclusive use of a family member 

Important Note - These are just some of the conditions. It's vital to check with the Rubicon technical staff on how the rules apply for granny annexes in your area.

  • Converting Existing Outbuildings: If you have a suitable outbuilding, such as a large garage, you might only need to apply for a change of use instead of full planning permission (although full building regs will still apply).

Seeking Professional Help

Rubicon Granny Annexe Floor Plan

While navigating planning permission processes can be complex, it's not something you have to tackle alone. Here's where a professional planner or architect can be invaluable. They can:

  • Advise you on permitted development rights and planning permission requirements.
  • Help design an annexe that meets regulations and integrates seamlessly with your property.
  • Prepare and submit planning applications on your behalf, increasing your chances of approval.

On all these aspects, Rubicon Garden Rooms can offer full professional advice

Granny Annexe Options

Once you've clarified the planning permission situation, it's time to consider the type of granny annexe that best suits your needs and budget. Here are some popular options:

  • Brick-Built Annexes: These offer a permanent extension to your home. They can be built to match the existing house or create a contemporary contrast. However, they will require full planning and building regulation compliance, and are the most expensive options.
  • Timber-Framed Annexes: A faster and potentially more affordable option than brick-built structures. Timber offers excellent insulation properties and a modern aesthetic.
  • Rubicon Modular Annexes: These part-prefabricated units are delivered and assembled on-site, offering a quick and cost-effective solution. Taking half the time to build, and typically costing half as much as a traditional build, they are a cost effective solution for additional living space.
  • Converted Outbuildings: As mentioned earlier, converting a large shed or garage can be a viable option, provided it meets space and amenity requirements, but this will require compliance with all building regulations.

Key Considerations for Granny Annexe Design

When designing your granny annexe, prioritise functionality and comfort for your family member. Here are some key aspects to consider:

  • Accessibility: If mobility is an issue, ensure level access, wide doorways, and grab rails in bathrooms to cater for the limitations of an elderly relative.
  • Lighting: Ample natural light and well-placed task lighting are essential for safety and comfort.
  • Heating: Consider energy-efficient heating systems suitable for a smaller space. Electric heating can be a good high efficiency option.
  • Security: Install smoke and carbon monoxide detectors and even consider security alarms for peace of mind.
  • Layout: Design a functional layout that maximises space and caters to the resident's needs. Open-plan living areas can create a feeling of spaciousness.
Inside a Rubicon granny annexe

Granny Annexe Building Regulations

Even if you don't need planning permission, a granny annexe built by traditional methods must comply with building regulations. You will need to engage an Architect and a Structural Engineer and you will find compliance both costly and frustratingly onerous.

For that reason, at Rubicon we advise constructing an annexe using the Mobile Homes Act, which as mentioned previously, will save both cost and timescales. Whilst the rules are complex from a manufacturing perspective, it is much simpler and cost effective for the client, and we have all the technical staff at hand to guide you through the simplified process.

Budgeting for Your Granny Annexe

The cost of your granny annexe will vary depending on the factors mentioned above together with the size, materials, design complexity, and any required groundwork. Here's a rough breakdown:

  • Planning and Building Regulations: Allow £1,500 to £2,500 for professional fees and building regulation approvals.
  • Construction Costs: This varies depending on the type of build method used as per the above mentioned options. Expect to pay between £2,000 and £3,000 per square metre for a basic brick-built annexe. By comparison, an 8m x 4m Rubicon one bedroom annexe is priced around £55,000 inc vat.

Additional Costs: Don't forget to factor in:

  • Connection to utilities (electricity, water, drainage)
  • Internal features like fitted bedrooms, fireplaces etc
  • Furniture, blinds, curtains
  • Landscaping and access considerations

Funding Options for Granny Annexes in the UK

Several financial options can help make your granny annexe project more achievable:

  • Selling a House: Most annexes are funded through the sale of an elderly persons home, which has often become too large and unmanageable as a relative gets older. Obviously this can take time for funds to be released, however, clients can secure a Rubicon annexe with just a £1500 deposit and installation is then deferred until the house sale is complete.
  • Equity Release: If you're a homeowner aged 55 or over, equity release schemes allow you to access some of the value tied up in your property. However, it's a complex financial product with ongoing interest charges that erode the value of your estate. It's crucial to seek independent financial advice before considering equity release.
  • Remortgaging: If you have sufficient equity in your home, you might be able to remortgage to release funds for the project. This can offer a more competitive interest rate compared to equity release. However, remember remortgaging extends your mortgage term and increases your monthly repayments.
  • Secured Loans: These loans are secured against the value of your property, typically offering lower interest rates than unsecured loans. However, there's a risk of repossession if you can't keep up with repayments.
  • Unsecured Loans: These personal loans offer a quick and straightforward way to access funds, but they typically come with higher interest rates.
  • Government Grants: In some cases, you may be eligible for government grants to help with the cost of adaptations for disabled or elderly individuals. Explore schemes like Disabled Facilities Grants (DFGs) offered by your local council.

For a free, friendly consultation, contact Rubicon today, and we’ll be happy to discuss your granny annexe project.