Single-storey, double-storey, rear and side extension drawings for Dacorum homes — measured to Dacorum Borough Council's design guidance, delivered in days and revised free until your decision, with a free approval-odds check before you commit.
Dacorum Borough Council granted 87% of the householder planning decisions it made in its latest published year — level with the 87% England-wide householder average. Extensive Metropolitan Green Belt covers the rural borough, concentrating growth on the three main towns and allocated sites, which is where a policy-literate drawing pack earns its keep. Its dominant Georgian (1714–1837), Victorian (1837–1901), interwar (1918–1939) and postwar (1945–1970) housing stock sets the design brief on most streets.
The permitted-development ceilings are fixed: 40m³ of new roof volume for a terraced loft and 50m³ for a semi or detached house under Class B, plus a 3m single-storey rear extension on a terrace or 4m on a detached house under Class A. Dacorum carries at least one Article 4 direction, and conservation areas including Hemel Hempstead Old Town, Berkhamsted and Tring remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Dacorum is determined against an 8-week statutory target.
Hemel Hempstead (a postwar New Town of planned neighbourhoods around the Marlowes centre), Berkhamsted (a historic canal-side market town in a Chilterns setting), Tring (a historic market town at the Chilterns gap), Kings Langley (a historic commuter village with a conservation-area core), Aldbury (a model rural conservation village below the Chilterns) and Bovingdon (a rural Green Belt village) — these are the Dacorum pockets our drawings cover most. Heritage designations here include Hemel Hempstead Old Town, Berkhamsted, Tring, Aldbury, Kings Langley and Bovingdon. Dacorum Borough Council weighs each proposal against the Dacorum Core Strategy 2006–2031 (adopted September 2013), where the Chilterns National Landscape (AONB) covers and adjoins Berkhamsted and Tring, adding landscape-protection constraints on design and siting. Converted and purpose-built flats appear across Hemel Hempstead and the town centres, and none of them hold householder permitted-development rights.. On roofs the borough is pitched tiled roofs on the postwar New Town housing and steep tiled and gabled roofs on the historic market-town and village cores, over postwar New Town planned neighbourhoods across Hemel Hempstead around the Marlowes centre, medieval, Georgian and Victorian market-town cores at Berkhamsted and Tring, interwar and Victorian stock and vernacular cottages in the surrounding villages and larger detached housing on the Chilterns fringe.
Dacorum homes come in a handful of recurring shapes, and each one points to a different extension. The borough is built largely from postwar New Town planned neighbourhoods across Hemel Hempstead around the Marlowes centre, medieval, Georgian and Victorian market-town cores at Berkhamsted and Tring, interwar and Victorian stock and vernacular cottages in the surrounding villages and larger detached housing on the Chilterns fringe, so a Victorian terrace usually wants a rear or side-return infill, while an interwar semi has room for a wider single-storey wrap or a two-storey side addition. Dacorum Borough Council judges every one of them against the Dacorum Core Strategy 2006–2031 (adopted September 2013), weighing footprint, height and the impact on the house next door before it looks at the elevations.
That is why the drawings decide the outcome. We set the extension depth against the permitted-development limits precisely, keep the eaves and ridge within the allowances, and plot the 45-degree daylight lines to the neighbours' windows so the case officer can see the amenity test is passed. Extensive Metropolitan Green Belt covers the rural borough, concentrating growth on the three main towns and allocated sites, so we design around it from the first sketch rather than discover it at validation.
Dacorum also protects whole streets — Hemel Hempstead Old Town, Berkhamsted, Tring, Aldbury, Kings Langley and Bovingdon among them. Dacorum's Article 4 directions, confirmed in November 2022, cover employment and town-centre areas and retain the requirement for planning permission to convert identified properties to residential use, and the borough's twenty-five conservation areas add further character controls. On designated land the larger-home extension route and most side extensions stop being permitted development, so we confirm your address against those layers before drawing a line.
Plenty of Dacorum extensions are permitted development and need no planning application — a single-storey rear extension within the depth and height limits is the common case. You will normally need to apply to Dacorum Borough Council if any of these apply:
We draw the footprint, the ridge and eaves heights and the neighbours' daylight on the page — the relationships Dacorum Borough Council's officers weigh first — and submit a validation-complete pack, whether that is a lawful development certificate, a prior-approval notification or a full householder application.
Below is Dacorum Borough Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. Dacorum grants a fair share of householder applications, with green-belt containment, the Chilterns AONB and its many conservation areas the recurring constraints on larger schemes. A complete, policy-literate extension pack anticipates those pressure points before submission, which is why professionally drawn applications are decided faster and refused less often than DIY ones.
Source: MHCLG planning application statistics (householder decisions, England, 1 April 2025 - 31 March 2026). Compare every borough on our London approval-rate league table.
Tell us about your project and get a fixed, no-obligation quote back within one working day. If you don't need planning permission at all, we'll tell you that too — for free.
Across Hemel Hempstead, Berkhamsted and Tring, the extension that lands most often is the single-storey rear addition — a glazed kitchen-diner across the back of the house, kept within the permitted-development depth or taken to a full application where the ground floor wants more. On the borough's postwar new town planned neighbourhoods across hemel hempstead around the marlowes centre, a side-return infill frequently pairs with it to square off the plan; on wider larger detached housing on the chilterns fringe, a two-storey side or rear extension can add a bedroom above without swallowing the garden.
The Chilterns National Landscape (AONB) covers and adjoins Berkhamsted and Tring, adding landscape-protection constraints on design and siting. We size the extension to the amenity and daylight tests, match the roof and materials to the host house, and keep enough garden to satisfy Dacorum Borough Council's space standards — so the scheme answers the borough's questions before an objection can raise them. Where permitted-development rights are used up or removed, we prepare the householder application to the council's extension design guidance instead.
We draw extensions on every street in the borough. A few of the neighbourhoods where Dacorum projects come up most often:
Extension drawings for Hemel Hempstead's a postwar New Town of planned neighbourhoods around the Marlowes centre — footprint-checked, daylight-tested and drawn to Dacorum Borough Council's guidance.
Extension drawings for Berkhamsted's a historic canal-side market town in a Chilterns setting — footprint-checked, daylight-tested and drawn to Dacorum Borough Council's guidance.
Extension drawings for Tring's a historic market town at the Chilterns gap — footprint-checked, daylight-tested and drawn to Dacorum Borough Council's guidance.
Extension drawings for Kings Langley's a historic commuter village with a conservation-area core — footprint-checked, daylight-tested and drawn to Dacorum Borough Council's guidance.
Extension drawings for Aldbury's a model rural conservation village below the Chilterns — footprint-checked, daylight-tested and drawn to Dacorum Borough Council's guidance.
Extension drawings for Bovingdon's a rural Green Belt village — footprint-checked, daylight-tested and drawn to Dacorum Borough Council's guidance.
The right extension in Dacorum depends on your house type and how much garden you can give up. This is how the main options compare on planning route and what they add.
| Extension type | Permitted development? | What it adds | What Dacorum Borough Council checks |
|---|---|---|---|
| Single-storey rear | Often, within 3m/4m depth (6m/8m via prior approval) | Bigger kitchen-diner across the back | Depth, height, neighbour daylight (45°) |
| Side-return infill | Sometimes, if within width and height limits | Squares off an L-shaped ground floor | Width vs the original house, glazing to boundary |
| Two-storey rear/side | No — full application | Extra bedroom or bathroom above | Bulk, overlooking, 7m rear-boundary gap |
| Wraparound (rear + side) | No — full application | Whole-width open-plan ground floor | Combined footprint and garden retained |
Route depends on your street — conservation areas such as Hemel Hempstead Old Town and Berkhamsted and Article 4 directions can remove permitted-development rights.
A fixed process built around how Dacorum Borough Council validates and decides householder extension applications — most drawings are submission-ready within seven days of survey.
Tell us your Dacorum postcode and house type. We confirm your conservation and Article 4 status, how much permitted-development depth you have left, and score your odds against live Dacorum Borough Council decisions.
We measure the existing footprint, floor and eaves levels, boundary distances and the neighbours' window positions — the numbers the depth limits and daylight tests depend on.
Chartered designers develop the single-storey, two-storey or side extension to your brief, drawn inside the permitted-development limits or to Dacorum Borough Council's extension design guidance.
We submit the certificate, prior-approval notice or application, manage validation and case-officer queries, and revise the drawings free until Dacorum Borough Council issues its decision.
Not always. A single-storey rear extension up to 3 metres deep on a terrace or semi, or 4 metres on a detached house, and no higher than 4 metres, is usually permitted development. In Dacorum you will need to apply to Dacorum Borough Council for two-storey extensions, side extensions wider than half the house, anything forward of the front wall, deeper rear extensions under the larger-home prior-approval route, and any extension in a conservation area such as Hemel Hempstead Old Town and Berkhamsted.
Standard permitted development allows 3 metres on a terraced or semi-detached house and 4 metres on a detached one. The larger-home extension scheme can double that to 6 or 8 metres, but it needs a prior-approval notification to Dacorum Borough Council and a neighbour-consultation period, and it does not apply on designated land such as Dacorum's conservation areas. We confirm which route your property qualifies for before drawing.
Two-storey and double-storey extensions almost always need a full householder application to Dacorum Borough Council, because they fall outside permitted development on most homes. The council looks closely at bulk, overlooking of neighbours and the 7-metre gap a two-storey rear extension must keep from the rear boundary. We design to those tests and show the daylight and privacy angles on the drawings.
A householder planning application in Dacorum runs to a statutory eight-week target, a larger-home prior-approval notification to around six weeks including the neighbour-consultation period, and a lawful development certificate to eight weeks. Incomplete submissions stall at validation, so we submit a complete pack and manage officer queries to keep the decision on schedule. Dacorum Borough Council is the decision-maker.
Yes — planning permission and building regulations are separate consents, and almost every extension needs both. Planning governs whether you can build it; building control governs how it is built, covering structure, insulation, drainage and fire safety. We prepare the building-regulations drawings alongside the planning set so Dacorum Borough Council's building control or an approved inspector can sign the work off.
Every house and brief is different, so we price each Dacorum extension individually and send a fixed, no-obligation quote back within one working day. It covers the full drawing pack with free revisions until Dacorum Borough Council approves, and we tell you upfront whether your extension qualifies as permitted development. Call 020 7864 7245 to get started.
Answer five quick questions and get a free planning score for your exact address — instantly. Then, if you want the full picture, unlock the detailed analysis: your council's live approval rates, local precedents, constraints on your street and a step-by-step route to permission.
Same fixed quotes, same fast drawings — wherever your project is.