Garden room drawings in the City of London

Conservation areas and listed buildings in the Square Mile

The City has 28 conservation areas and Historic England records 637 list entries, including 86 at Grade I, plus 1 Article 4 direction. In an area this small, a garden is very likely to be in the setting of something protected.

For houses, the national order is direct: Garden buildings within the curtilage of a listed building are not permitted development. In a conservation area, there is a further limit: On article 2(3) land, no outbuilding between a side wall and the boundary.

Heritage is therefore the first filter, and we look at it before any design. A building in the setting of a listed church, hall or terrace is judged for its effect on that setting, so the drawings include a section and a photograph of the view.

The Barbican and other estates

The City's best-known homes are on the Barbican Estate, which is listed and has its own management guidance, the Barbican Estate Listed Building Management Guidelines: Volume I Introduction and Volume II Residential (SPD). Residents of the estate who want to add a structure to a terrace or podium garden are working inside that guidance, and consent is likely to be needed for an addition of any kind.

We do not claim a garden room is routine on such a site. What we do is read the guidance, decide whether a light, removable structure is realistic, and tell you plainly if it is not. That honest answer is part of the service, and it costs far less than a refused application.

A measured building survey is where this kind of project often starts, since terrace and podium dimensions are not on any public plan.

What the City's figures mean for householders

The City decided 1 householder application in its latest published year, granting 100 per cent. A single decision tells you nothing, so we do not use it as evidence of how the council behaves. We treat the City of London Local Plan 2015, adopted in 2,015, as the document the scheme will be tested against.

The average City home sold for £710,652, and prices changed by -17.4 per cent over the past year. A refused application is a costly delay at any value.

The City's community infrastructure levy is £251.05/m² (Riverside); £159.00/m² (Rest of City) [schedule rates £150 and £95]. A small garden building seldom triggers it, but we mention it so that it is not a surprise.

Courtyards, terraces and what we can draw

If your outdoor space is a courtyard or a roof terrace, the question is not planning alone. A structure on a terrace adds load to a slab, and one in a courtyard may block a means of escape or a neighbour's rights of light. We raise those points in our first reply, before any drawing work.

Where a light structure is realistic, we draw it as a lightweight frame with a green roof, set well back from parapets, with the load path shown on the section. The photographs and views we include are those an officer weighs when judging setting.

A party wall notice may follow if the structure touches a shared boundary, and we explain that in writing so the cost and timing are known.

Route, fee and building control

Where a house qualifies and nothing blocks it, a Lawful Development Certificate in the City of London records the position. Otherwise we prepare planning drawings in the City of London, and the fee for works within an existing home's boundary is £272.

Building Regulations apply separately. A detached room can be exempt: Detached single-storey building up to 30 m², no sleeping accommodation, at least 1 m from the boundary or substantially non-combustible, is exempt. Where it cannot, our building regulations drawings in the City of London cover fire separation and structure, which matter more in a dense site.

The height rule for any outbuilding is the same as elsewhere: Max 2.5 m if within 2 m of a boundary; otherwise 4 m dual-pitched roof or 3 m any other roof.

Price and next steps

A set starts at £495 with VAT included. It includes the block plan, floor plan, elevations, a section and a materials note, and a second chartered technologist checks each sheet. If the council asks for changes we redraw them free of charge.

For our wider service in the area see architectural drawings in the City of London. Owners just outside the Square Mile can look at garden room drawings in Islington and Hackney.