Three Rivers, Hertfordshire
Architectural drawings in Three Rivers
Three Rivers has a Green Belt guidance note written specifically for house extensions, and 76 per cent of the district is Green Belt. Our architectural drawings in Three Rivers start from £745 including VAT and are drawn to that note. We are MCIAT chartered architectural technologists, and the first check of your address is free.
Fixed quote after a free constraints check
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- Fixed fees, VAT included
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Three Rivers in numbers
| Measure | Value | Period | Source |
|---|---|---|---|
| Green Belt share of the council area | 76 % of council area covered by green-belt polygons | — | planning.data.gov.uk |
| Conservation areas | 19 named conservation areas published by the council | — | planning.data.gov.uk |
| Listed building entries | 352 list entries (Historic England, within the LPA boundary) | — | planning.data.gov.uk |
| Householder decisions | 617 decisions | 1 July 2025 - 30 June 2026 | assets.publishing.service.gov.uk |
| Householder applications granted | 90.9 % | 1 July 2025 - 30 June 2026 | assets.publishing.service.gov.uk |
| Householder applications decided in time | 98.1 % decided within 8 weeks or an agreed extended period | 1 July 2025 - 30 June 2026 | assets.publishing.service.gov.uk |
| Larger home extension prior approvals granted | 11 decisions | 2025 Q2 to 2026 Q1 (1 Apr 2025 to 31 Mar 2026) | assets.publishing.service.gov.uk |
| Lawful development certificate applications (PS1) | 192 certificates | 2025 Q2 to 2026 Q1 (1 Apr 2025 to 31 Mar 2026) | assets.publishing.service.gov.uk |
| Households living in a house | 79.7 % of households living in a house or bungalow (detached, semi-detached or terraced) | Census 2021 | nomisweb.co.uk |
| Average price, detached | 1,206,251 GBP | 2026-07 | publicdata.landregistry.gov.uk |
| Local plan | Three Rivers Local Plan: Core Strategy (2011), Development Management Policies LDD (2013) and Site Allocations LDD (2014) | — | threerivers.gov.uk |
| Supplementary planning document | SPG 3: Green Belt (extensions to dwellings) | — | threerivers.gov.uk |
| Borough CIL charging schedule | Three Rivers CIL Charging Schedule (adopted February 2015) | from 2015-04-01 | threerivers.gov.uk |
A blank value means the figure has not been published, not that there are none. Check your own address with the council.
Constraints check: Three Rivers
What we check first on any Three Rivers address. Counts are for the whole council area.
- A · Conservation areas
- 19 named conservation areas published by the council
- C · Listed building entries
- 352 list entries (Historic England, within the LPA boundary)
Three Rivers' Green Belt guidance for extensions
The council's supplementary document for this is SPG 3: Green Belt (extensions to dwellings). It is the first thing we open for a Three Rivers extension, because it governs how much a home can grow when the land around it is protected.
Its tests are about proportion and openness, so the drawing set has to show the original house clearly: the footprint, the roof and any earlier additions. We mark these on the plans, so the officer does not have to reconstruct the history of the building from old applications.
With so much of the district in the Green Belt, many homes here meet this test whatever the project.

The local plan behind Three Rivers decisions
Policy comes from the Three Rivers Local Plan: Core Strategy (2011), Development Management Policies LDD (2013) and Site Allocations LDD (2014). The core strategy dates from 2,011, and the later documents fill in detail on development management and allocated sites.
In practice that means a design is read against several documents at once. We list the relevant policies in the design note that goes with the drawings, so you can see what the council will weigh.
How fast and how often Three Rivers decides yes
The council decided 617 householder applications between July last year and June this year, and 90.9 per cent were granted. Timing stands out: 98.1 per cent were decided within eight weeks or an agreed extension.
For minor applications the in-time figure was 98.4 per cent, with 82.1 per cent granted. A quick decision helps a builder plan the start date, though it does not alter what the officer decides.
These are past figures for the district. They are not a promise for your house.
Prior approval and lawful development in Three Rivers
Larger home extensions can use prior approval. In the latest published year the council granted 11 and refused 14, a split that rewards a careful neighbour assessment.
Owners also applied for 192 lawful development certificates that year. If you are building under permitted development, a Lawful Development Certificate in Three Rivers is the written proof.
Heritage in Three Rivers
The council publishes 19 conservation areas. Historic England lists 352 entries: 3 at Grade I, 14 at Grade II* and 333 at Grade II.
There are also 2 registered parks and gardens, 3 scheduled monuments and 1 entry on the Heritage at Risk Register. If your house is listed or sits in a conservation area, we explain which consents apply before you spend on design.
From first call to submission in Three Rivers
Send the address and a few lines on what you want. We reply the same working day if your message arrives before three in the afternoon, and we report back on the planning constraints before any fee is taken for design.
Drawings follow in about seven days after the survey. You review them, we adjust, and the independent check is done by someone who did not draw the set. Only then does the application go to the council, through the Planning Portal, with the forms and certificates completed.
Should the council ask for changes, our redraws are free until approval.
Levy, prices and housing in Three Rivers
Three Rivers charges the Community Infrastructure Levy under its Three Rivers CIL Charging Schedule (adopted February 2015), with three residential areas. The charge is highest in Area A, lower in Area B and nil in Area C.
79.7 per cent of households live in a house or bungalow, and 70.9 per cent own their home. A detached house averages £1,206,251 and a terraced one £461,977.
The architectural drawings we prepare in Three Rivers
Typical work includes planning drawings in Three Rivers, side return extension drawings and double-storey extension drawings. For the build, construction drawings turn the permission into a set a builder can price.
Over the border, see our council pages for Buckinghamshire, Hillingdon and Hertsmere.
What you receive


Services in Three Rivers
Questions
Can I extend a house in the Green Belt in Three Rivers?
Often, within limits. The council's SPG 3: Green Belt (extensions to dwellings) sets the test, and we design to it after measuring the original house.
How much are architectural drawings in Three Rivers?
Householder planning drawings start at £745 including VAT, fixed up front. The council's own application fee is separate.
Does Three Rivers charge the Community Infrastructure Levy?
Yes, in three residential areas under its Three Rivers CIL Charging Schedule (adopted February 2015). We tell you which area applies and whether your project is liable.
How long does Three Rivers take to decide a householder application?
In the latest figures 98.1 per cent were decided within eight weeks or an agreed extension. That describes the past, not your case.
Sources and dates
- planning.data.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- assets.publishing.service.gov.uk, retrieved
- assets.publishing.service.gov.uk, retrieved
- nomisweb.co.uk, retrieved
- publicdata.landregistry.gov.uk, retrieved
- threerivers.gov.uk, retrieved
- threerivers.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- nomisweb.co.uk, retrieved
- Contains public sector information licensed under the Open Government Licence v3.0.
- Contains OS data © Crown copyright and database right 2026.
- Contains HM Land Registry data © Crown copyright and database right 2026. This data is licensed under the Open Government Licence v3.0.
- Contains Historic England data © Historic England 2026. Contains Ordnance Survey data © Crown copyright and database right 2026.

Tell us about your property.
We check the constraints, then send a fixed fee. Messages before 3pm get a reply the same working day.