Garden room and outbuilding plans in London start at £515 with us. The price covers drawings for permitted development or for a planning application, and a check against the 2.5 metre height rule that applies close to a boundary. The price has no separate survey part.
A garden room is the simplest building project most owners will ever do. It is also one where a few centimetres matter, because the permitted development limits are tight and a breach turns a free project into an application. This article gives the limits, the cases where permission is needed, and what the drawings should show.
What the plans cost
The £515 buys drawings of the garden room in plan, elevation and section, a site plan that places it in the garden and shows its distance from each boundary, and a written check against the rules. If the room fits permitted development, the drawings support a certificate or simply protect you later. If it does not, they go with a planning application. The council fee for either is separate.
The limits that decide whether you need permission
Outbuildings sit under Class E of the General Permitted Development Order. The building must be for a purpose incidental to the enjoyment of the house, such as a home office, gym or studio, and must stay within a list of limits.
- Height: 2.5 metres within 2 metres of the boundary; 3 metres in other cases; 4 metres where the roof is dual-pitched.
- Eaves: no higher than 2.5 metres.
- Storeys: one only.
- Coverage: with all other buildings except the original house, no more than 50% of the garden.
- Position: not forward of the principal elevation, and not within the curtilage of a listed building.
- No verandah, balcony or raised platform.
On designated land the rules tighten. In a conservation area or other article 2(3) land, an outbuilding may not stand between a side wall of the house and the boundary. In a national park, the Broads, an area of outstanding natural beauty or a World Heritage Site, buildings more than 20 metres from the house may cover no more than 10 square metres in total.
Use, conditions and building regulations
Class E allows a building incidental to the house, not a separate home. A garden room used as a bedroom for a lodger or let to someone else is a change of use, and its permitted development right is gone. Rights are also lost where the house's own planning permission carries a condition on outbuildings, since nothing in the Order permits development contrary to a condition.
Building regulations are a separate question. Small, simple outbuildings are often exempt, but one with sleeping accommodation, or with a size or siting that falls outside the exemption, is not. The drawings note the construction so building control can see what applies.
The figures in this article, and where they come from
An outbuilding within 2 metres of the boundary may be no higher than 2.5 metres; elsewhere the limit is 3 metres, or 4 metres with a dual-pitched roof.
Source: legislation.gov.uk, GPDO 2015, Schedule 2, Part 1, Class E, E.1(e)The eaves of an outbuilding under Class E may not exceed 2.5 metres in height.
Source: legislation.gov.uk, GPDO 2015, Schedule 2, Part 1, Class E, E.1(f)Buildings, enclosures and containers other than the original house may not cover more than 50% of the area of the curtilage.
Source: legislation.gov.uk, GPDO 2015, Schedule 2, Part 1, Class E, E.1(b)An outbuilding under Class E must have no more than 1 storey.
Source: legislation.gov.uk, GPDO 2015, Schedule 2, Part 1, Class E, E.1(d)In an AONB, the Broads, a National Park or a World Heritage Site, outbuildings more than 20 metres from the house may cover no more than 10 square metres in total.
Source: legislation.gov.uk, GPDO 2015, Schedule 2, Part 1, Class E, E.2Article 3(4) of the GPDO says nothing in the Order permits development contrary to any condition imposed by a planning permission.
Source: legislation.gov.uk, GPDO 2015, article 3(4)
Questions people ask
Do I need planning permission for a garden office?
Not if it meets the Class E limits and the house is not a flat, listed or under a condition or Article 4 direction removing the right. The height by the boundary and the 50% garden limit are the usual traps.
Can I sleep in a garden room?
Using it occasionally as a guest room is incidental use. Using it as a separate home, or letting it, is a change of use that needs permission. The same room may also trigger building regulations if it is used for sleeping.
Does a raised deck count?
A verandah, balcony or raised platform takes the building out of Class E. The drawings show finished floor level against ground level so the point is clear.
Do I need a certificate for a garden room?
It is optional, but it settles the question for a buyer's solicitor. A lawful development certificate with us starts at £715 inc survey, and the council fee is half of the planning fee.
What if my garden slopes?
Height is measured from the ground next to the building, and on sloping ground that matters. The drawings show sections with the ground level, so the officer can see the greatest height rather than guess.
Garden Room & Outbuilding Plans: from £515
What you get
- Permitted development or planning drawings
- 2.5m height rule check
- A site plan showing distances to every boundary
The total you pay, fixed in writing before you commit. Council fees are separate and paid to the council. Prices checked 24 October 2026.
How our garden room & outbuilding plans service works