Garden room drawings for Harrow homes
Whether a Harrow garden room needs planning permission depends on its height, its position and how much of the garden it covers. DrawingsDirect, MCIAT chartered architectural technologists, draws garden rooms for Harrow houses from £495, so you can see where the limits fall before you order.
Fixed fee from £495 · all prices
Prefer to talk it through?
Height, boundary and coverage: the three checks
Permitted development for outbuildings sits in Class E, Part 1, Schedule 2 of the General Permitted Development Order 2015. Within 2 metres of the boundary the building can be no higher than 2.5 metres, and all buildings, enclosures and containers together must not cover more than 50% of the curtilage once the original house is excluded. The wording is on legislation.gov.uk.
On a narrow Harrow garden, where the room may sit within 2 metres of a fence on both sides, test the height limit first. A scaled section showing the finished floor level and the roof edge against the fence tells you early, and it is much cheaper to lower a roof on a drawing than on a built frame.
Size thresholds in the Building Regulations
A detached building of up to 15 square metres with no sleeping accommodation is exempt from the Building Regulations. One of up to 30 square metres is exempt if it is single storey, has no sleeping accommodation and sits at least one metre from the boundary or is substantially non-combustible (Building Regulations 2010, Schedule 2, Class 6).
Anything that will be used as a bedroom falls outside both. See our guide on whether a garden room needs planning permission for the planning side.
Our analysis of the MHCLG Planning Data Platform (bulk snapshot retrieved 19 Oct 2026) finds 31 conservation-area entries for Harrow on the national register.
Harrow's certificates of lawful development
Our analysis of MHCLG planning application statistics, table PS1, counts 704 certificates of lawful development decided by Harrow across the eight quarters 2024 Q3 to 2026 Q2. Applicants use them to get written confirmation that a proposed or existing building is lawful, for example one put up under permitted development.
If you want one, the drawings must match the building exactly. Our lawful development certificate drawings service prepares them.
Harrow conservation areas: check the address first
Our analysis of the MHCLG Planning Data Platform (bulk snapshot retrieved 19 Oct 2026) finds 31 conservation-area entries for Harrow on the national register. Look up your address on Harrow's conservation area map first. If it falls inside one, treat the rules above as a starting point only and confirm with the council before design work begins.
Planning applications for other work at the same address may also be affected: see our planning permission drawings in Harrow.
What we charge
Garden room drawings start from £495. The pricing page lists the other fixed fees, and the garden room drawings page describes the service. Send your Harrow address and the size of room you want through the quote form.
Sources
Every figure on this page, where it comes from and a link to the original.
| Figure | Source | Link |
|---|---|---|
| 2.5 metres | GPDO 2015 Sch 2 Pt 1 Class E.1(e)(ii): outbuilding within 2 metres of the curtilage boundary, max height (source wording: 2.5 metres) | www.legislation.gov.uk |
| 50% | GPDO 2015 Sch 2 Pt 1 Class E.1(b): buildings, enclosures and containers must not cover more than 50% of the curtilage (excluding the original house) | www.legislation.gov.uk |
| 15m2 | Building Regulations 2010 Sch 2 Class 6 para 3: exempt detached building with floor area not exceeding 15m2 and no sleeping accommodation (source wording: 15m2) | www.legislation.gov.uk |
| 30m2 | Building Regulations 2010 Sch 2 Class 6 para 1: exempt detached single-storey building not exceeding 30m2, no sleeping accommodation, at least one metre from the boundary or substantially non-combustible (source wording: 30m2) | www.legislation.gov.uk |
| 704 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 31 | Our analysis of MHCLG Planning Data Platform conservation-area and article-4-direction datasets (bulk snapshot retrieved 19 Oct 2026) | www.planning.data.gov.uk |
| £495 | DrawingsDirect starting fixed fee for garden room drawings, from the published price list | drawingsdirect.co.uk |
Questions people ask
What is the height limit for a garden room in Harrow?
How much of my garden can I build on?
Does a 15 square metre garden room need Building Regulations approval?
Photographs: David Howard (CC BY-SA 2.0); Derek Harper (CC BY-SA 2.0).
