Within the house curtilage
The building must sit within the land forming part of the house. Class E does not allow an outbuilding forward of the principal elevation.
TRJ CONSTRUCTION · PLANNING & DESIGN
Planning permission for
granny annexes & garden rooms.
A clear plan for your next chapter.
Understand the planning route before you build. TRJ Construction helps homeowners develop garden-room and granny-annexe proposals, prepare drawings and coordinate applications across Hertfordshire, North London, Essex and Buckinghamshire.
Guidance for homes in England. Your property and intended use shape the route.
START WITH HOW YOU WILL USE THE SPACE
Garden room.
Family annexe.
The right route.
The intended use matters as much as the dimensions.
A garden room, private gym or hobby studio may qualify as an incidental outbuilding. A granny annexe designed for residential accommodation needs a different assessment. We develop the brief around who will use the building, its relationship to the main home and the site constraints.
Tell us your postcode, approximate dimensions and how you want to use the space. That gives us a practical starting point for the design and planning discussion.
TYPICAL PERMITTED DEVELOPMENT LIMITS
Check the essentials.
Then check your site.
These are key Class E outbuilding conditions for houses in England. Every applicable condition must be satisfied; meeting the height limit alone is not enough.
2.5 m
Close to a boundary
If any part of the building is within two metres of a boundary, the maximum overall height is 2.5 metres.
4 m / 3 m
Roof and eaves heights
Elsewhere, the maximum is 4 metres with a dual-pitched roof or 3 metres with another roof. Eaves must not exceed 2.5 metres.
Single-storey buildings
The outbuilding must be single storey. Verandas, balconies and raised platforms are restricted; check proposed decking as part of the design.
50%
Space left around the original house
Additions and other buildings must not cover more than half the land around the original house. Existing extensions and outbuildings count.
Incidental use
The building must serve an incidental purpose connected to the house. Separate self-contained living accommodation is outside these outbuilding rights.
Listed properties, designated land, Article 4 directions, planning conditions and the type of property can alter the position. These householder rights do not apply to flats and maisonettes.
WHY ANNEXES NEED A CLEAR BRIEF
Independent comfort.
A considered proposal.
A family annexe can bring together a kitchen, bathroom, bedroom and living space. These are residential facilities, so do not assume that ordinary garden-building permitted development rights apply.
A well-prepared proposal explains the family use and how the annexe remains connected to the main household. The layout, position, land levels, overall height and glazing should be considered together, including the effect on neighbouring properties.
We help coordinate these details in the drawings and application. The local planning authority determines the application; approval is never assumed.
THE PLANNING PERMISSION PROCESS
From first conversation
to a buildable design.
Our design-and-build team keeps the proposed building, application drawings and eventual construction connected. The scope is agreed for your project.
Understand your site
Start with a free, no-obligation conversation. Share your address, garden photographs, access details, approximate size and intended occupants or use.
Shape the proposal
Develop the layout, external appearance and location. Coordinate plans, elevations and any relevant levels or visualisations with the planning brief.
Prepare and coordinate
Agree the application route, drawings and supporting information. We can coordinate submission and communication with the council within the agreed service.
Build to the agreed scope
Once the necessary consents and pre-start requirements are in place, coordinate building control, foundations, the SIP structure, services and finishes.
WHY CHOOSE TRJ CONSTRUCTION?
One team.
A joined-up project.
Our work brings together SIP construction, planning drawings and practical on-site delivery. We consider how the proposed building will actually be constructed, connected and used.
From the first design conversation to the build process, you have a clear point of contact. Explore completed TRJ projects and what can be included, then confirm your own specification and quotation.
PLANNING DRAWINGS & LAYOUTS
See the ideas
on paper.
Explore planning drawings, elevations and layout ideas. Select an image to enlarge it and move through the full gallery.
FREQUENTLY ASKED QUESTIONS
More clarity.
A better starting point.
Answers to common questions about granny annexe planning permission, garden buildings and building control in England.
Do granny annexes need planning permission?
A new garden annexe intended for sleeping and self-contained living will normally need a planning application. Class E outbuilding rights do not cover separate self-contained accommodation. The council assesses the proposed use and relationship to the main home.
Can a granny annexe be built under permitted development?
An incidental garden room and a residential annexe have different planning requirements. A small footprint, SIP construction or family occupation does not automatically make a new annexe permitted development. Establish the planning route before ordering the building.
What size garden building can I build without planning permission?
There is no single floor-area allowance for every garden. The proposal must meet all relevant Class E conditions, including its use, height, position and the combined coverage of additions and buildings around the original house.
How high can a garden building be near a boundary?
Where any part is within two metres of the curtilage boundary, the Class E maximum overall height is 2.5 metres. Away from that zone, the usual limits are 4 metres for a dual-pitched roof or 3 metres for another roof, with eaves no higher than 2.5 metres.
Can my granny annexe have a kitchen and bathroom?
Yes, subject to the approved design and use. A kitchen, bathroom, bedroom and living area can support family accommodation, but the proposal must follow the appropriate planning route and any conditions attached to the permission.
Do annexes also need building regulations approval?
Planning and building control are separate. A habitable annexe normally needs building regulations approval covering the structure, fire safety, insulation, ventilation, drainage and relevant services. The small detached-outbuilding exemptions do not cover sleeping accommodation.
Can I let an annexe or use it as a separate dwelling?
Permission for accommodation ancillary to the main house does not automatically authorise an independent dwelling or a rental use. Check the decision notice and conditions with the local planning authority before changing how it is occupied.
What is a lawful development certificate?
A lawful development certificate formally confirms that a precisely described existing or proposed development is lawful for planning purposes. It is a different route from a planning application and does not replace building regulations approval.
PLANNING & BUILDING CONTROL
Two separate checks.
Planning considers whether the development and use are acceptable. Building regulations address how the building is constructed and performs. Agree both routes early, including structural details, insulation, ventilation, drainage and electrical provision.
Official guidance checked 12 October 2026: GOV.UK householder technical guidance · Planning Portal outbuildings · Lawful development certificates · Outbuilding building regulations. Rules differ elsewhere in the UK.
STILL HAVE A QUESTION?
Let’s plan
your new space.
Send your postcode, garden photographs and ideas for a garden room or family annexe. We will discuss design, planning support and the next steps for your property.
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