You're imagining stepping out from the bedroom onto a balcony, or building a raised deck off the back of the kitchen so the garden and the house feel like one space. It's a natural thing to want - and it's one of the clearest "no" answers in the permitted development rules.
Balconies: never permitted development. Raised platforms over 300mm above ground level: also not permitted development. Juliet balconies with no external platform: usually fine. Low decking at or near ground level: usually fine. The rules are specific and there is no workaround.
The GPDO explicitly excludes "the construction of a veranda, balcony or raised platform" from permitted development under Class A (extensions). The same exclusion appears in Class E (outbuildings). This means a balcony or raised platform is never PD, regardless of size, height, position, or how much of your PD allowance remains. If you want one, you need a householder planning application (£548 as of April 2026).
No size makes a balcony permitted. No position makes it permitted. The exclusion is absolute.
The government's technical guidance defines a raised platform as a surface raised more than 300mm above the natural ground level. A timber deck at or below 300mm is not caught by the exclusion and is usually permitted development - it simply counts as a hard surface improvement to the garden, similar to a patio.
Above 300mm, it's a raised platform and needs planning permission. This is measured from the natural ground level, not from any surface you've added. On a sloping garden, one end of a flat deck can easily exceed 300mm even if the other end is at ground level - and if any part exceeds the threshold, the whole structure is caught.
A Juliet balcony is a railing or balustrade fitted to the outside of a window or door opening, with no external platform to step onto. Because there is no floor and no platform, a Juliet balcony is not a balcony or raised platform as defined in the legislation, and is normally permitted development.
This is a common and practical alternative to a full balcony on a loft conversion or first-floor extension. You get the feeling of openness and the visual connection to the outside, without triggering the balcony exclusion. The window or door behind it still needs to comply with any relevant conditions - for example, side-facing windows on a loft conversion must be obscure-glazed and non-opening below 1.7 metres.
You build a single storey rear extension with a flat roof. The roof is strong enough to walk on. You add some planters and outdoor furniture and start using it as a terrace. This is not permitted development. The moment you use the roof of an extension as a balcony, veranda, or raised platform, you have created development that requires planning permission.
This catches homeowners regularly. The extension itself may be perfectly lawful under PD, but using its roof as an outdoor terrace is a separate act of development - and one that is explicitly excluded. If your council receives a complaint from a neighbour about overlooking, they can issue an enforcement notice requiring you to stop using the roof and remove any railings or furniture.
Common mistakes that cost money
Using a flat extension roof as a terrace. The extension is PD. Using the roof as a platform is not. These are separate questions and getting the first right doesn't make the second lawful.
Building decking on a sloping garden without checking the height. If any part exceeds 300mm above natural ground level, the whole deck needs planning permission.
Assuming a Juliet balcony with a small ledge is fine. If the ledge is wide enough to stand on - even briefly - it may be considered a platform by the council. A true Juliet balcony has no floor whatsoever.
PD Assessment Tool
A professional permitted development assessment from a planning consultant typically costs £400-600 and takes 2-3 weeks. This tool checks your specific project against every condition - including the balcony and raised platform exclusions - and produces a formal document you can share with your builder or your council.
The first step checks whether your property is eligible - about two minutes, completely free. If your property qualifies, the full project assessment is £47.
Content verified against the Town and Country Planning (General Permitted Development) (England) Order 2015 (as amended), Classes A and E of Part 1, Schedule 2 (legislation.gov.uk, revised version) and the government's technical guidance (September 2019). SI 2026/313 confirmed no changes to Classes A or E. This page is for general information only and does not constitute legal advice.
April 2026