Garden Annexe Cost Garden Room Pricing Blog

Which Construction Method Lasts the Longest?

When designed and built correctly, SIPs, timber frame and traditional brick construction can all provide decades of reliable performance. Longevity depends less on the construction method itself and more on the quality of materials, workmanship and ongoing maintenance. Choosing an experienced manufacturer and following a regular maintenance schedule will help maximise the lifespan of your annexe.

What Is the Best Granny Annexe in the UK?

The best granny annexe is one that meets your family’s needs, fits your available space and is built to a high standard. Look for a company that offers bespoke designs, energy-efficient construction, transparent pricing and a comprehensive installation service. It’s also worth considering the quality of materials, warranty, customer reviews and aftercare support rather than focusing solely on the lowest price.

Do you have a showroom?

Instead of maintaining a costly showroom, we’ve chosen a more efficient approach that keeps our prices competitive. The cost of running a showroom ultimately has to be passed on to customers, and we’d rather you invest your budget in your garden annexe than in our overheads.

What if my property is in a conservation area?

Conservation areas restrict permitted development rights, but the Caravan Act route is not affected by conservation area status. We will advise you on the specific rules for your property during your free consultation.

Can I rent out a Caravan Act annexe?

No. An annexe installed under the Caravan Act must remain ancillary to the main dwelling and cannot be rented out or given a separate postal address.

What is a Lawful Development Certificate and do I need one?

An LDC is formal confirmation from your local council that your annexe is lawful. It isn’t legally mandatory, but we strongly recommend obtaining one for your peace of mind and to protect your property’s future sale value. We manage this application on your behalf.

Does the Caravan Act save me VAT?

Yes. Annexes that qualify under the Caravan Act are zero-rated for VAT. On a project costing £100,000, this represents a saving of £20,000 compared with a traditional brick-built extension.

Can I build a granny annexe without planning permission?

Yes, in most cases. Modular annexes built to Caravan Act specifications — including all of The Green Room’s annexes — typically do not require full planning permission, provided the homeowner conditions are met.

Can I upgrade to underfloor heating?

Yes. Fastwarm underfloor heating is available as an optional extra. It’s a popular choice for laminate floors and works well as the main heating source.

Is heating included in the bathroom or shower room?

Yes. For any room with a shower, we install the Ecostrad Cube iQ electric towel rail. It keeps both the space and your towels warm.

Can I control the heating from my phone?

Yes, the WiFi-enabled Ecostrad iQ Ceramic and Cube iQ towel rails can be controlled via smartphone app or linked with smart home assistants like Alexa and Google Home.

What heating comes as standard in a Green Room building?

All Green Room buildings come with Ecostrad iQ Ceramic electric radiators as standard. These offer reliable warmth, modern design, and smart or manual control options.

What’s included in your all-inclusive price?

All kitchens, bathrooms and fitted furniture are part of our standard build. There are no hidden charges.

Can wardrobes be built in?

Absolutely. We can fit sliding door wardrobes with internal drawers and shelving to your chosen size and layout.

Do your bathrooms come with storage?

Yes. Our bathrooms use vanity units and space-saving designs to keep everything neat and practical.

Can you include appliances in my kitchen?

All main appliances like ovens, hobs and fridges are included as standard. You can also add extras like microwaves, washers and dishwashers.

Do I get to choose my kitchen layout and colour?

Yes. We’ll walk you through layout ideas and show samples of doors, worktops and splashbacks so you can choose the finish that works best for you.

How do I get started?

Just fill out our quote request form or give us a call. We’ll guide you through the next steps from there.

Can I make changes during the build?

In some cases, yes. We’ll always do our best to accommodate small changes. It’s best to finalise your design early to avoid delays.

Do you offer a full turnkey service?

Yes. At The Green Room, we manage every stage of your project, from the initial site survey and design through to groundworks, foundations, utility connections, installation and final handover. We also complete the plumbing, electrics, plastering, kitchen and bathroom installation, so your granny annexe or garden room is ready to use when we leave.

Choosing a turnkey provider means you only deal with one company throughout the project. You’ll have a single point of contact from start to finish, making the process simpler, reducing the need to coordinate multiple contractors and giving you confidence that every stage is managed to the same high standard.

Who handles planning and building control?

We take care of it all. Whether it’s a full planning application or a Lawful Development Certificate, we deal with the local authority on your behalf. For further information, please see our planning page.

How involved do I need to be in the process?

We manage everything for you, but you’ll be involved in all the key decisions – from layout and finishes to planning approval. We’ll keep you informed every step of the way.

Do you visit the site before starting work?

Yes. Every project begins with a detailed site visit. We assess access, ground conditions and services, then talk through design options with you face to face.

What happens after I request a quote?

Once you request a quote, we’ll email you a selection of plan layouts that include guide prices and specifications. These examples provide a useful starting point and help you understand what’s included in our granny annexes.

If you like what you see, simply let us know and we’ll arrange a free site survey at your property. During the visit, we’ll discuss your requirements, answer any questions and assess whether the project is suitable for your garden.

We’ll also assess the best location for your granny annexe, evaluate the ground conditions and utility connections, and bring samples of cladding, flooring and interior finishes. This gives you the opportunity to explore your options without visiting a showroom.

Following the site survey, we’ll prepare a bespoke design and provide a clear, fixed-price quotation tailored to your project. We’ll explain exactly what’s included, so you can compare quotes with confidence.

If you decide to proceed, we’ll manage every stage of the project, including planning support where required, groundworks, foundations, utility connections, manufacturing, installation and the complete internal fit-out. We’ll keep you informed throughout the process, and when we hand over your new granny annexe, it will be ready to move into.

Can your buildings include kitchens and bathrooms?

Absolutely. All granny annexes come with a fully fitted kitchen and bathroom as standard. Garden rooms can also include these features if needed.

What sizes are available?

There’s no fixed size. Each building is custom-built, so whether you want a compact office or a two-bedroom annexe, we’ll design it to fit your garden and lifestyle.

Can I choose the exterior finish?

Yes. We offer a wide range of low-maintenance cladding options, from classic timber looks to modern fibre cement finishes. These are available in a variety of colours.

Are your garden rooms and annexes insulated?

Yes. We manufacture every granny annexe and garden room using Structural Insulated Panels (SIPs), which provide outstanding insulation and excellent energy efficiency. They keep your annexe warm in winter, cool in summer and help reduce energy costs throughout the year.

What types of buildings do you offer?

We design and install bespoke granny annexes, garden lodges, offices, hobby rooms and garden rooms. All are made to order and tailored to your space and needs.

Who will be working on my site?

All work is completed by our own trusted team. We don’t use subcontractors you’ve never met, you’ll always have the same friendly team on-site from start to finish.

Do you offer installation for garden lodges across Northamptonshire?

Yes. We carry out full turnkey installations for garden lodges and annexes across Northamptonshire and the surrounding areas.

Is the annexe or garden lodge usable straight away after installation?

Yes. Once we’ve completed the build and the final checks are done, your building is fully functional and ready to decorate.

How disruptive is the installation process?

We aim to keep disruption to a minimum. Most builds are completed quickly, and we manage all site access, deliveries and waste removal. Our teams are friendly, respectful and tidy.

Will I need to arrange building control inspections?

No. We arrange all building control sign-offs as part of the process. You’ll receive certification when the work is complete, giving you full peace of mind.

Do you manage all trades during the build?

Yes. We provide a fully managed service. Our team includes groundworkers, builders, electricians, plumbers and plasterers – all coordinated by us so you don’t have to manage a thing.

Are service connections included in the installation?

Yes. We include connection to your home’s electricity, water and foul drainage systems. If a pump or longer trench run is needed, we’ll let you know up front.

Do I need to prepare the garden before you start?

No. We’ll assess your site during the survey and include any clearance, levelling or preparation in your quote. If you need to move sheds, trees or fencing, we can advise beforehand.

Do you take care of all the groundwork?

Yes. We handle all aspects of groundwork including trenching, drainage, electrical connections and screwpile or concrete pad foundations. You won’t need to bring in extra trades.

What is included in the installation service?

Our installation includes foundations, construction of the building, internal plastering, electrics, heating, flooring, bathroom and kitchen fitting, plus connection to all mains services.

Do granny annexes add value to my home?

Yes. In most cases, a well-built annexe will increase the overall property value and make it more attractive to multigenerational buyers.

Can I get a quote for a granny annexe near me?

Yes. We offer free, no-obligation quotes across Northamptonshire and the surrounding area.

Get a Free Granny Annexe Quote Here

Can I rent out my granny annexe?

Most granny annexes are approved for family use only. If you plan to rent it out, different planning rules apply. We can advise on this during your consultation.

Are granny annexes permanent or mobile?

Some granny annexes are designed to meet the legal definition of a caravan under the Caravan Act, which means they can be relocated if necessary. However, moving an annexe is a specialist operation that usually requires professional lifting equipment and transport. In practice, most homeowners install a granny annexe as a long-term addition to their property.

If a granny annexe exceeds the size limits or does not meet the criteria set out in the Caravan Sites Act, it is generally treated as a permanent building. In these circumstances, the project will usually require full planning permission and must comply with the relevant planning policies and Building Regulations.

Can a granny annexe be used for other family members?

Yes. While often built for elderly relatives, granny annexes are also ideal for adult children, guests, or anyone needing independent space.

What’s included in the price of a granny annexe?

Everything. We include foundations, service trenching, kitchen and bathroom fitting, electrics, heating, flooring and finishes. Our quotes are fully inclusive.

Can I customise the layout and finishes?

Yes. Every garden annexe we build is made to order. You choose the floor plan, kitchen units, bathroom fittings, exterior cladding and more. We’ll help you design it to suit your space and needs.

Do you build granny annexes in Northamptonshire?

Yes. We’re based in Corby and complete projects all across Northamptonshire and nearby areas. We know the local planning system well and offer full support from start to finish.

What is a granny annexe?

A granny annexe is a self-contained home built in your garden. It usually includes a bedroom, bathroom, kitchen and living space, allowing a relative to live close by while keeping their independence.

Are garden lodges suitable for long-term living?

Yes. They are designed as permanent homes. Many of our customers use them for elderly relatives, adult children, or guest accommodation.

What does the price of a garden lodge include?

Our price includes everything: certification, siting, SIPs construction, kitchen, bathroom, wardrobes, electrics, heating and final finishes. There are no hidden extras.

Do you install garden lodges in Northamptonshire?

Yes. Most of our projects are local, but we also cover surrounding counties.

Are garden lodges insulated for all-year use?

Yes. Just like our annexes, our lodges are manufactured with SIPs panels for excellent thermal performance. They’re warm, quiet and energy efficient all year round.

Do garden lodges come with kitchens and bathrooms?

Yes. All of our garden lodges are fully equipped with a fitted kitchen, bathroom, and all the essentials needed for day-to-day living. Everything is included in the quoted price.

Is planning permission required for a garden lodge?

No, planning permission is not required, but a  Lawful Development Certificate is. We handle the LDC application for you as part of our service. For further information, please see our planning page.

Are your garden lodges classed as mobile homes?

Yes, our lodges meet the legal definition of a mobile home under the Caravan Act.

How much does a garden lodge cost?

Prices for our one-bedroom garden lodges start from £85,000, including kitchen, bathroom, installation and all services. Larger or custom lodge designs may cost more, depending on layout and specification.

What is a garden lodge?

A garden lodge is a self-contained living space, often constructed under Caravan Act rules. It includes everything needed for independent living and is ideal for a family member or guest.

Where can I find your price list?

You can visit our Garden Room Price Guide page for starting prices and size examples. For a personalised quote, just request your own garden annexe quote here.

Is VAT included in the price?

Yes. All our quotes include VAT, so the figure you see is the figure you’ll pay.

Can I get a fixed price before I commit?

Yes. Once we’ve visited your site and agreed on a layout, we’ll provide a full written quote. This will be a fixed price for the full project.

Do garden rooms cost less than granny annexes?

Generally, yes. A garden room without kitchen or bathroom is cheaper to build than a full annexe. But adding features like a shower room or kitchenette will increase the price.

What affects the final price of a granny annexe or garden room?

The size, layout, number of rooms, and your choice of finishes all affect the final cost. We’ll work with your budget to suggest options that make the most of your space.

Are service connections included in the cost?

Yes. We include trenching and connection to mains water, foul drainage and electricity. If a pump or additional works are needed, we’ll advise you clearly before we start.

Is everything included in the price?

Yes. Our prices include planning support, foundations, full installation, service connections, kitchen, bathroom and all internal finishes. There are no hidden extras.

Can you visit my Northamptonshire home for a site survey?

Yes. We offer free, no-obligation site surveys across Northamptonshire. During the visit we’ll assess access, garden space, drainage options and talk through design ideas with you.

What’s the most popular type of granny annexe in Northamptonshire?

One-bedroom annexes with a small kitchen and en-suite are very popular in the area. They offer enough space for independent living while still keeping loved ones close by. We also build two-bedroom annexes for larger families or for those wanting guest space.

Can I use a granny annexe in Northamptonshire as a holiday let?

It depends on local authority rules and the use class of the building. Most granny annexes are for family use, but if you’re thinking about holiday letting or renting it out, we recommend checking with your local planning team. We can help advise on this during your consultation.

Do your granny annexes add value to homes in Northamptonshire?

Yes, they do. A high-quality annexe can increase your property value and make your home more attractive to buyers. Many estate agents across Northamptonshire recognise annexes as a strong selling point, especially for families looking for multigenerational living.

How long does it take to build a granny annexe in Northamptonshire?

Most builds in Northamptonshire are completed within 4–6 weeks, depending on the size and layout. We manage everything from the groundworks to the final internal finishes. All done by our experienced in-house team.

Can I view a completed granny annexe in Northamptonshire?

Yes. Many of our past customers are based in Northamptonshire and we have local case studies available. In some cases, we may be able to arrange a private viewing by appointment with a previous customer.

Are there any local planning rules for granny annexes in Northamptonshire?

While the general rules for garden annexes are the same across the UK, each local authority may have slightly different preferences. We have experience dealing with councils across Northamptonshire and handle all planning or LDC applications on your behalf. For further information, please see our planning page.

Do you install granny annexes in Northamptonshire?

Yes. We’re based in Corby and build granny annexes across Northamptonshire and surrounding counties. Whether you’re in Kettering, Northampton, Wellingborough or further out, we can offer a full design and build service.

Get a free quote for a granny annexe in Northamptonshire

Can you work around tricky access?

Yes. We’ve built in all kinds of locations with tight or restricted access. Our team will assess this during your site survey and advise on any extra steps needed. We can also build modularly and carry materials through the house if needed.

What’s the difference between a garden lodge and a granny annexe?

The key differences come down to size and the type of Local Authority approval required.

Garden Lodges

  • Must fall within the size limits set by the Caravan Act.
  • Only need a Lawful Development Certificate — full planning permission isn’t required.

Granny Annexes

  • Can be built within the same Caravan Act size limits, in which case they also only need a Lawful Development Certificate.
  • Can also be built larger than the Caravan Act allows — but if so, full planning permission is required.

In short: Every Garden Lodge stays within Caravan Act size limits. A Granny Annexe can too, but it has the flexibility to go bigger if you need the extra space — you’ll just need full planning permission in that case.

Can you install a kitchen or bathroom?

Yes. Every granny annexe includes a kitchen and bathroom as standard. For garden rooms, we can add a toilet, shower, or kitchenette depending on your needs. Everything is fully fitted and connected by our qualified team.

What guarantees do you offer?

All of our garden buildings come with a 10-year comprehensive guarantee. We also offer insurance-backed warranties through IWA, including deposit protection (subject to policy fees). This gives you full peace of mind from start to finish.

Do you offer finance?

We don’t offer finance directly, but we can supply a detailed quote that you can take to your mortgage provider or broker. Because our annexes add value to your home, they are often accepted by lenders for equity-based loans.

How much does a granny annexe cost?

Costs vary depending on the size and layout. A compact garden room with en-suite starts from around £52,000, while a larger home with kitchen and bedroom typically starts from £85,000. Our pricing is fully inclusive, so there are no surprise costs later.

What is a Lawful Development Certificate?

A lawful development certificate (LDC) is a legal document from a local planning authority that confirms a development is lawful, meaning it doesn’t require planning permission. We can help you apply for this as part of your project. For further information, please visit the planning portal.

Are your buildings mobile or permanent?

All our granny annexes are permanent buildings, which will require planning permission. Our garden lodges comply with the Caravan Act and will require a lawful development certificate.

What size garden do I need for a garden annexe?

There’s no fixed size, but we recommend at least 30–35 square metres of usable garden space for a one-bedroom annexe. We offer a free site survey to assess what will work best in your garden.

For more details book a free Garden Room Quote 

Can I live in a granny annexe/building full time?

Yes, our granny annexes are built for full-time living. They are insulated, connected to mains utilities, and comply with building regulations. They include a bathroom, kitchen, living space and sleeping area, just like a small home.

What areas do you cover?

We’re based in Northamptonshire and cover all surrounding counties and areas within around 120 miles. If you’re unsure, just give us a call and we’ll confirm.

Can I use a garden room as a home office?

Yes. Many of our customers use garden rooms as offices, studios, or hobby rooms. They’re fully insulated and finished to a high standard, making them ideal workspaces all year round.

Do I have to pay council tax on a granny annexe?

If a dependent relative lives in the garden annexe, you are usually exempt from council tax. Rules can vary slightly depending on your local council, but we can help guide you.

Can I customise the design?

Absolutely. Every building is made to order. You can choose the layout, kitchen and bathroom finishes, cladding colour, window style, and more. We’ll help you design something that fits your garden and lifestyle. See more options on our Garden Annexe Products page.

Do I need to connect utilities?

Yes, all granny annexes require connections to electricity, water and drainage. We include all service trenching and connections in our all-inclusive price. We don’t leave you to sort this out yourself.

Are your buildings insulated for year-round use?

Yes. All our garden buildings use structural insulated panels (SIPs). This keeps them warm in winter and cool in summer. They are fully insulated, energy efficient and low maintenance.

How long do the Garden Buildings take to build?

Most builds take between 4 to 6 weeks, depending on size and design. We manage the full project from groundwork to final fittings, so everything runs smoothly and on schedule.

What’s the difference between a granny annexe and a garden room?

A granny annexe is a self-contained living space, usually used as a home for a family member. It includes a kitchen, bedroom and bathroom. A garden room is usually used for work or leisure and doesn’t normally include sleeping or full-time facilities.

Do I need planning permission for a granny annexe?

For an annexe, you will typically need to apply for either Full Planning Permission or a Lawful Development Certificate (LDC) from your Local Planning Authority (LPA). We handle this process on your behalf.

Whichever route you take, our team handles the paperwork and contacts the local authority on your behalf. For further information, please see our planning page.

Planning & Permissions

Do I need planning permission for a granny annexe?

For an annexe, you will typically need to apply for either Full Planning Permission or a Lawful Development Certificate (LDC) from your Local Planning Authority (LPA). We handle this process on your behalf.

Whichever route you take, our team handles the paperwork and contacts the local authority on your behalf. For further information, please see our planning page.

What is a Lawful Development Certificate?

A lawful development certificate (LDC) is a legal document from a local planning authority that confirms a development is lawful, meaning it doesn’t require planning permission. We can help you apply for this as part of your project. For further information, please visit the planning portal.

Are there any local planning rules for granny annexes in Northamptonshire?

While the general rules for garden annexes are the same across the UK, each local authority may have slightly different preferences. We have experience dealing with councils across Northamptonshire and handle all planning or LDC applications on your behalf. For further information, please see our planning page.

Can I use a granny annexe in Northamptonshire as a holiday let?

It depends on local authority rules and the use class of the building. Most granny annexes are for family use, but if you’re thinking about holiday letting or renting it out, we recommend checking with your local planning team. We can help advise on this during your consultation.

Build & Installation

How long do the Garden Buildings take to build?

Most builds take between 4 to 6 weeks, depending on size and design. We manage the full project from groundwork to final fittings, so everything runs smoothly and on schedule.

Can you work around tricky access?

Yes. We’ve built in all kinds of locations with tight or restricted access. Our team will assess this during your site survey and advise on any extra steps needed. We can also build modularly and carry materials through the house if needed.

What size garden do I need for a garden annexe?

There’s no fixed size, but we recommend at least 30–35 square metres of usable garden space for a one-bedroom annexe. We offer a free site survey to assess what will work best in your garden.

For more details book a free Garden Room Quote 

Do you install granny annexes in Northamptonshire?

Yes. We’re based in Corby and build granny annexes across Northamptonshire and surrounding counties. Whether you’re in Kettering, Northampton, Wellingborough or further out, we can offer a full design and build service.

Get a free quote for a granny annexe in Northamptonshire

Can I view a completed granny annexe in Northamptonshire?

Yes. Many of our past customers are based in Northamptonshire and we have local case studies available. In some cases, we may be able to arrange a private viewing by appointment with a previous customer.

Can you visit my Northamptonshire home for a site survey?

Yes. We offer free, no-obligation site surveys across Northamptonshire. During the visit we’ll assess access, garden space, drainage options and talk through design ideas with you.

Features & Customisation

Are your buildings insulated for year-round use?

Yes. All our garden buildings use structural insulated panels (SIPs). This keeps them warm in winter and cool in summer. They are fully insulated, energy efficient and low maintenance.

Can I customise the design?

Absolutely. Every building is made to order. You can choose the layout, kitchen and bathroom finishes, cladding colour, window style, and more. We’ll help you design something that fits your garden and lifestyle. See more options on our Garden Annexe Products page.

Can I use a garden room as a home office?

Yes. Many of our customers use garden rooms as offices, studios, or hobby rooms. They’re fully insulated and finished to a high standard, making them ideal workspaces all year round.

Can you install a kitchen or bathroom?

Yes. Every granny annexe includes a kitchen and bathroom as standard. For garden rooms, we can add a toilet, shower, or kitchenette depending on your needs. Everything is fully fitted and connected by our qualified team.

What’s the difference between a granny annexe and a garden room?

A granny annexe is a self-contained living space, usually used as a home for a family member. It includes a kitchen, bedroom and bathroom. A garden room is usually used for work or leisure and doesn’t normally include sleeping or full-time facilities.

What’s the difference between a garden lodge and a granny annexe?

The key differences come down to size and the type of Local Authority approval required.

Garden Lodges

  • Must fall within the size limits set by the Caravan Act.
  • Only need a Lawful Development Certificate — full planning permission isn’t required.

Granny Annexes

  • Can be built within the same Caravan Act size limits, in which case they also only need a Lawful Development Certificate.
  • Can also be built larger than the Caravan Act allows — but if so, full planning permission is required.

In short: Every Garden Lodge stays within Caravan Act size limits. A Granny Annexe can too, but it has the flexibility to go bigger if you need the extra space — you’ll just need full planning permission in that case.

Pricing, Value & Guarantees

How much does a granny annexe cost?

Costs vary depending on the size and layout. A compact garden room with en-suite starts from around £52,000, while a larger home with kitchen and bedroom typically starts from £85,000. Our pricing is fully inclusive, so there are no surprise costs later.

Do your granny annexes add value to homes in Northamptonshire?

Yes, they do. A high-quality annexe can increase your property value and make your home more attractive to buyers. Many estate agents across Northamptonshire recognise annexes as a strong selling point, especially for families looking for multigenerational living.

Do you offer finance?

We don’t offer finance directly, but we can supply a detailed quote that you can take to your mortgage provider or broker. Because our annexes add value to your home, they are often accepted by lenders for equity-based loans.

What guarantees do you offer?

All of our garden buildings come with a 10-year comprehensive guarantee. We also offer insurance-backed warranties through IWA, including deposit protection (subject to policy fees). This gives you full peace of mind from start to finish.

Do I have to pay council tax on a granny annexe?

If a dependent relative lives in the garden annexe, you are usually exempt from council tax. Rules can vary slightly depending on your local council, but we can help guide you.

Get in Touch with The Green Room

Our team of down-to-earth experts genuinely care about great garden spaces and excellent customer service. Whether you’re just starting to explore your options or ready to move forward with your project, we’re here to help.