Ancillary Buildings: What You Need To Know

Thinking of adding a garden office, gym or granny annexe to your home but not sure what you can and can’t do? We have done all the research for you so here is what you need to know about ancillary buildings.

Planning Permission and Ancillary Buildings

If the outbuilding is ancillary to the main dwelling and not used as a residence, if built within size limitations, it will be covered under your Permitted Development rights (alterations you can make without planning permission).

However, an outbuilding must serve the main house and not be independent of it, so you can’t use it as self-contained accommodation, or as a bedroom, bathroom or kitchen. Therefore, without planning permission, an outbuilding could not be an annexe to house an elderly relative and using it as a holiday let is not permitted.

Outbuildings are not covered by Permitted Development in the grounds of a listed home, so you will have to apply for planning. If your home is in an Area of Outstanding Natural Beauty, National Park, Conservation Area or other types of specially designated land, then you will not be able to build an outbuilding to the side of the property. For it to be covered by Permitted Development it must also be at least 20m away from the property and be 10m² or less.

It is important to consider that planning authorities vary in their approach to annexes and some will try to resist the development even if ticks all the boxes for permitted development. In this instance, it could be easier to construct the outbuilding for some other use, such as a home office, and then change the use once the work is complete.

Compliance with Building Regulations: if in doubt, always check with your local planning authority. Whether or not planning permission is required, the building will need to comply with the Building Regulations.

How Long Does It Take?

If a planning application is required, it should take 8-10 weeks for a decision following a completed registration. If the property is an annexe, the planners will usually place a condition on its use to prevent letting out to a third party.

It is important to note that permitted development work can commence without notice, unless Building Regulations or a Party Wall agreement is required, for example, if the building work is on or near a boundary with your neighbours.

How Much Will This Cost?

A planning application for a garden outbuilding currently costs £172 in England. Building Regulations consent will cost from £200-£300 upwards, depending on scale.

image shows a pile of money to demonstrate a paragraph talking about planning permission costs

What Reasons Could Planning Permission Be Denied?

“Material considerations” will be considered when determining the impact on neighbouring properties and on the setting.

Taller structures that overlook or overshadow neighbours’ properties are less likely to be acceptable. Single-storey designs are unlikely to be an issue, providing the windows won’t overlook neighbouring properties.

Access down the side of a property for vehicles to reach an annexe can be an issue if it could impact on neighbours.

For detailed technical advice on permitted development rights for householders click here  and for more information on planning permission and to apply online click here.

Building Work

For most cases, it should be possible to decide on whether your project is permitted or not. Remember, your proposal must pass all the tests necessary to be classed as permitted development. It is useful to tick off the limits and conditions as you work through them.

You should check with your local planning authority as to whether permitted development rights have been withdrawn by what is known as article 4 directions, and whether other consents, such as listed building consent, are needed. Remember also that many projects will be subject to the building control regime, whether planning permission is required.

If your project passes the development tests, then you don’t need to apply for planning permission, and you can now finally go ahead with your project!

Before you do start work it is important to get guidance from your local planning authority and building control body and get professional advice whenever possible.

To find out who your Local Planning Authority is there is a handy postcode checker here.

Lawful Development Certificate

If there is any question over whether your proposal passes the permitted development tests you have do have other options. One option is it may be possible to alter your plans to ensure they meet permitted development limits and conditions.

Another alternative option is to apply for a lawful development certificate (LDC). This is not the same as planning permission but is proof that your household building work is lawful.

For more information on lawful development certificates and to apply online click here.

Planning Application

If permitted development has been rejected, then your one remaining option is to apply for planning permission. It is worth noting that even if a proposal may not meet permitted development criteria that does not mean it cannot be completed. An application for planning permission allows the local planning authority to assess your proposal and decide whether to approve it. Applying for detailed or full planning permission for a new house or a conversion in England is currently £462. For more advice/technical information you can head to the Planning Portal online application site.

image shows planning for ancillary buildings

Planning Permitted

Once planning permission has been granted you are almost ready to start work on your ancillary building!

As you can see, what you need to know about ancillary building is quite straight forward – especially when you use a full turnkey service like ours. We take care of each and every part of the project for you, meaning that you can relax and just wait for the keys to your brand-new home.

Feel ready to start your own project?

If you have any questions about our annexe building service or want to book a free consultation, simply get in touch. A member of our team will be happy to answer any questions you may have.

Recent Projects

Hot tub outside granny annexe

Ingrid & Donna Giles

Ingrid & daughter Donna Giles opted for a custom designed two-bed annex with large outdoor decked area.
granny annexe projects

Haughton’s Home

We recently visited the Haughton Family to see how garden annexe living was working out for them. It’s safe to say they feel like it was the perfect choice. Watch the video below to hear their experience of this ever-growing lifestyle.
Clarke custom granny annexe

Custom Engineered

This large, two-bedroom custom annexe was finished to an exceptionally high specification, with open-plan kitchen and living area.
Webb-Annexe

Kenneth Webb

Ken Webb lives with beloved dog Charlie in his two bedroomed annexe as an alternative to a retirement flat. Read his story.

Download Your Free Annexe Brochure

Simply fill in the form and you will be emailed a link to download our 32 page annexe brochure.

    Simply fill in the form and you will be emailed a link to download our 32 page annexe brochure.

    Request A Hard Copy?:








    Download Your Free Annexe Brochure

      Simply fill in the form and you will be emailed a link to download our 32 page annexe brochure.

      Request A Hard Copy?:








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