Areas / Three Rivers
Architects in Three Rivers
Detached and semi-detached houses in Rickmansworth, Croxley Green and Chorleywood often have room to extend, but most of the district is Green Belt, which limits how large an extension can be.
RIBA Chartered Practice · ARB-registered architects · Extensions, lofts and planning drawings
- FreeInitial consultationA conversation about your project, and a first view of what's possible, before any fee is agreed.
- FixedFee for each stageEvery stage is priced in writing before it starts. No hourly billing.
- 3DSee the design firstYour design is shown in 3D before it's submitted, while changes are still easy.
- FreeResubmissionIf planning is refused, we revise and resubmit at no extra design fee. Conditions
Much of our work in Three Rivers is on detached and semi-detached houses with generous gardens. Outside the built-up areas, Green Belt policy limits extensions to a size proportionate to the original house, so we check the planning history and the original floor area first.
The district's design criteria set clear depth limits for rear extensions. Where a larger scheme is justified, we set out the case with drawings and photographs of the surrounding houses.
Local planning points
Planning in Three Rivers
Checked November 2026. Planning policy changes, so we confirm the position for your address before you commit.
The district's design criteria set a general maximum depth of 3.6m for single-storey rear extensions, or 4m for detached houses, reduced where neighbours would be affected.
SourceRear extensions should not cross a 45-degree splay line drawn from the shared boundary, level with the neighbour's rear wall.
SourceAbout 76% of Three Rivers is Green Belt, where extensions that are disproportionate to the original house are not permitted.
SourceIn March 2026 the Housing Minister directed the council to add housing sites to its draft Local Plan, run a new consultation by 31 July 2026 and submit the plan by 30 November 2026.
Source
Our results
Our planning record in Three Rivers
Applications made to Three Rivers Council by F-Line Designs, Green Code Architects and their predecessor practices since 2018.
On 2 sites in Three Rivers, a revised scheme was approved after an earlier application was refused or withdrawn.
Source: council planning records, October 2026.
Services
What we draw in Three Rivers
- House extensions
- Loft conversions
- Basement conversions
- Planning permission
- Building regulations drawings
- Structural calculations
- Flat conversions
- Change of use
- New builds
- Interior design
Neighbourhoods we cover include Rickmansworth, Croxley Green, Chorleywood, Moor Park, Abbots Langley and South Oxhey.