How Much Does a Self Contained Granny Annexe Cost?

What’s included in the price of an iHus annexe?

Our pricing is fully turnkey, so the figure you’re quoted covers the whole project, from the first conversation to a finished annexe. Several services that other providers charge for are included at no cost with iHus:

• • In-depth consultation – we talk through your vision, needs and options before any contract, free of charge.

• • Site survey and assessments – a full survey of ground conditions, drainage and access, carried out free so your design suits your garden.

• • Architectural and design fees – bespoke design, CGI drawings and floor plans so you can see your annexe before you commit, all included.

• • Planning support – we manage the planning application on your behalf (more on planning below).

The following are built into your annexe price as part of the turnkey service:

• • Groundworks and foundations – prepared to suit your site’s ground conditions.

• • Labour and installation – experienced tradespeople handling electrics, plumbing and joinery.

• • Utility connections – bringing electricity, water and drainage to the annexe.

How much does a self contained garden annexe cost to build?

To give you an estimate of the cost, at iHus our garden annexes are available at a wide range of prices, to suit every budget.

The starting price is £100,538, which is the cost of our one bedroom annexe, ‘The Bawtry‘. At a width of 16.57 ft and a length of 23.13 ft, this represents great value for money.

Or, at the other end of our range, ‘The Wheatley‘ is a two bedroom annexe, costing £131,481. This annexe is a very generous size, at 19.85 ft wide and 32.97 ft long.

The cost of building a self contained garden annexe can vary considerably, depending on a range of different factors. The main factors that affect self contained garden annexe costs are:

• • The size – the larger the annexe, the more expensive it will be

• • How many rooms you need – typically, the higher the number of rooms, the higher the cost

• • The complexity of the design – more complex structures will cost more to build

• • The utilities that are required – these will include plumbing, electrical wiring and heating systems, for example

• • The choice of materials – high-end finishes and materials give the annexe a longer lifespan, but represent a higher initial cost

• • The type of annexe foundation – different foundations each have their own specific price point

• • The extent of your customisation – the more bespoke features you add, the more it will cost

• • How many windows or doors you include – windows and doors add extra costs to the construction

• • The finishes that you choose – flooring, countertops and other fixtures come at widely different price points, so find options that fit comfortably within your budget

What ongoing costs should you budget for?

Beyond the build, a granny annexe is inexpensive to run, but it’s worth planning for a few ongoing costs:

• • Repairs and upkeep – mostly light interior and exterior cleaning. We check in at six months and keep an open line afterwards, so any later questions are easy to raise.

• • Utility bills – usually lower than a full-sized home, and connected to your main supply. Costs depend on your provider and usage.

• • Grounds maintenance – keeping paths and landscaping around the annexe tidy, depending on your garden and choices.

What is a self contained garden annexe?

Self contained garden annexes are a highly effective, and surprisingly affordable, way to increase the usability of your outdoor space. A garden annexe is a permanent, secure and weather-proof structure, built in the garden of an existing property. With rising property prices and the cost of living crisis, annexes are becoming increasingly popular, particularly in areas where housing is expensive.

The key difference between annexes and other garden structures is that annexes are precisely designed for style, comfort and to be lived in. They can be customised to feature your pick from the full range of creature comforts, from bespoke kitchens and bathrooms to reading nooks, living areas and convenient outdoor storage.

Garden annexes are most commonly associated with ‘granny annexes’: purpose-built annexes that can be attached to a house or located in the garden. These give elderly relatives privacy and homely living areas while staying conveniently close to loved ones. Today, though, live-in garden annexes have flourished in popularity, making them a sought-after choice among young people, homeowners who love hosting, and grandparents alike.

Do you need planning permission for a self contained annexe?

The short answer is yes. If you are building a garden annexe, you will usually need to apply to your Local Planning Authority (LPA) for planning permission.

In the majority of cases, you can apply for the required planning permission by following the process of a Householder’s Planning Application, the same type you would need for an extension. If your LPA classes your annexe as a new dwelling, you will need to submit a Full Application instead. And if no one will be living in the annexe, planning permission may not be required at all.

Either way, we take care of the planning process on your behalf. With iHus, there are two routes depending on your annexe:

• • Classic Range – we manage the full application with your LPA, with a planning permission success rate of 94%.

• • 3632 Range – falls under the Caravan Act with a Certificate of Lawfulness, so full planning permission isn’t required.

The planning application fee itself averages around £2,200. And if permission is ever refused on a Classic Range annexe, our money-back guarantee refunds every penny you’ve spent with us so far, so the risk sits with us, not you. Further detail is covered at the free on-site consultation we offer.

For how council tax applies to an annexe, see our guide to granny annexe council tax rules.

Buying a self contained garden annexe from iHus

iHus is the leading annexe specialist in the UK. In 20 years we have built annexes for over 500 families and worked with more than 250 local planning authorities, across a choice of 12-plus designs. We are renowned for luxury annexes that combine state-of-the-art design with flexible, bespoke build options. You can see the full range of granny annexes, with sizes and prices, to find the right fit.

Our service is exceptional value for money, and our attentive team can support you through every step, from planning permission applications to customising your annexe with bespoke finishes. Every iHus annexe comes with a 10-year insurance-backed guarantee, so your new annexe stands as a long-term property investment.

To view our self contained garden annexes for yourself, you can either visit one of our community show homes in person, or request a brochure. Or, to arrange a free annexe consultation for your garden, speak to our experts today to find out exactly how much your dream garden annexe costs.