Back-of-house extension drawings for Dacorum homes — the glazed kitchen-diner across the rear, drawn to Dacorum Borough Council's depth and daylight limits, delivered in days and revised free until your decision, with a free approval-odds check first.
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.
The rear extension is the workhorse of Dacorum home improvement — it is how a dark back kitchen becomes an open family room facing the garden. Because 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, most back walls sit close to a neighbour on at least one side, and that proximity, not the design, is what Dacorum Borough Council scrutinises. The council reads the proposal against the Dacorum Core Strategy 2006–2031 (adopted September 2013), and the first line an officer draws is the 45-degree splay from the neighbour's nearest window.
So the drawings live or die on geometry. We set the depth against the exact permitted-development figure, hold the eaves and the flat-roof or lantern build-up under the 4-metre height ceiling, and show the projection tested against both the 45-degree plan angle and the 25-degree section angle to the neighbouring windows. Extensive Metropolitan Green Belt covers the rural borough, concentrating growth on the three main towns and allocated sites, so the rear elevation is composed around it rather than corrected after an objection.
Where the property sits in a conservation area — Hemel Hempstead Old Town, Berkhamsted, Tring, Aldbury, Kings Langley and Bovingdon among Dacorum's — the larger-home extension route is switched off and even a modest rear addition needs consent. 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. We confirm the designation before the survey.
Many single-storey rear extensions in Dacorum are permitted development and need no application. You will normally need to apply to Dacorum Borough Council, or use the larger-home prior-approval route, if any of these apply:
We draw the depth, the roof build-up and the daylight splays to each neighbour on the page — the tests Dacorum Borough Council's officers apply first — and submit a validation-complete pack, whether that is a lawful development certificate, a larger-home prior-approval notice or a full householder application.
Below is Dacorum Borough Council's real householder decision record, taken 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. Rear extensions turn most often on neighbour daylight and depth, so a drawing pack that proves those tests upfront is decided faster and refused less often than a DIY submission.
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 approved rear extension is typically a single-storey glazed box within the depth limit, roofed either flat with a lantern or in a shallow mono-pitch, and finished in brick or render to match the host wall. On the borough's postwar new town planned neighbourhoods across hemel hempstead around the marlowes centre, keeping the projection to the permitted-development figure often avoids an application entirely; where owners want the full 6 metres, the larger-home route succeeds when the neighbour-consultation period passes without a sustained objection.
The Chilterns National Landscape (AONB) covers and adjoins Berkhamsted and Tring, adding landscape-protection constraints on design and siting. We keep the extension inside the daylight splays, set any glazed roof below the first-floor cill, and retain the garden depth Dacorum Borough Council expects — so the back elevation answers the amenity case before a neighbour can lodge one. Two-storey rear extensions we draw with the 7-metre boundary gap and privacy screening resolved on the plan.
We draw rear extensions on every street in the borough. A few of the neighbourhoods where Dacorum back-of-house projects come up most often:
Rear extension drawings for Hemel Hempstead's a postwar New Town of planned neighbourhoods around the Marlowes centre — depth-checked, daylight-tested and drawn to Dacorum Borough Council's guidance.
Rear extension drawings for Berkhamsted's a historic canal-side market town in a Chilterns setting — depth-checked, daylight-tested and drawn to Dacorum Borough Council's guidance.
Rear extension drawings for Tring's a historic market town at the Chilterns gap — depth-checked, daylight-tested and drawn to Dacorum Borough Council's guidance.
Rear extension drawings for Kings Langley's a historic commuter village with a conservation-area core — depth-checked, daylight-tested and drawn to Dacorum Borough Council's guidance.
Rear extension drawings for Aldbury's a model rural conservation village below the Chilterns — depth-checked, daylight-tested and drawn to Dacorum Borough Council's guidance.
Rear extension drawings for Bovingdon's a rural Green Belt village — depth-checked, daylight-tested and drawn to Dacorum Borough Council's guidance.
How far you can extend at the back in Dacorum depends on your house type and the route you take. This is how the options compare.
| Route | Depth allowed | Consent needed | What Dacorum Borough Council checks |
|---|---|---|---|
| Standard permitted development | 3m terrace/semi · 4m detached | Lawful development certificate (optional) | Depth, 4m height, materials |
| Larger-home prior approval | 6m terrace/semi · 8m detached | Prior-approval notice + neighbour consultation | Neighbour objections on amenity |
| Full householder application | Beyond the above, or two-storey | Full planning permission | Daylight (45°/25°), bulk, garden retained |
| Conservation area | Case by case | Full planning permission | Character, roof form, boundary treatment |
The larger-home route is switched off on designated land — conservation areas such as Hemel Hempstead Old Town and Berkhamsted and Article 4 streets need a full application.
A fixed process built around how Dacorum Borough Council validates and decides rear-extension applications — most drawings are submission-ready within seven days of survey.
Send us your Dacorum postcode and house type. We confirm your conservation and Article 4 status, how much rear-extension depth you have under permitted development, and score your odds against live Dacorum Borough Council decisions.
We measure the original rear wall, floor and eaves levels, side and rear boundary distances and the neighbours' window positions — the numbers the depth limit and daylight splays depend on.
Chartered designers develop the single or two-storey rear extension to your brief, drawn inside the permitted-development limits or to Dacorum Borough Council's extension design guidance, with the daylight angles shown.
We submit the certificate, prior-approval notice or application, handle validation and case-officer queries, and revise the drawings free until Dacorum Borough Council issues its decision.
Often not. 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 involve Dacorum Borough Council for anything deeper via the larger-home route, for two-storey rear extensions, and for any rear extension in a conservation area such as Hemel Hempstead Old Town and Berkhamsted, where those permitted-development rights fall away.
The larger-home extension scheme lets a single-storey rear extension reach 6 metres on a terrace or semi, or 8 metres on a detached house — double the standard allowance. It is not automatic: you submit a prior-approval notification to Dacorum Borough Council, neighbours are consulted, and if one objects on amenity grounds the council rules on it. It also does not apply on designated land such as Dacorum's conservation areas.
It is the daylight test Dacorum Borough Council applies to protect neighbours. Drawn on plan, a line at 45 degrees from the midpoint of the neighbour's nearest ground-floor window should not be crossed by your extension; a companion 25-degree line is checked in section. If the projection breaches it, the extension is likely to be shortened or refused, so we test and prove it on the drawings before submission.
A two-storey rear extension almost always needs a full householder application to Dacorum Borough Council, as it sits outside permitted development on most homes. The council checks that it stays at least 7 metres from the rear boundary, does not overbear the neighbours and avoids new overlooking. We resolve the boundary gap, privacy and daylight on the plans so the application is decided on its merits.
Frequently, yes. If the rear extension involves work to a shared wall, building up to the boundary, or excavating foundations near a neighbour's structure, the Party Wall etc. Act applies and you must serve notice — this is separate from Dacorum Borough Council's planning decision. We flag it early and can prepare the drawings a party-wall surveyor needs alongside the planning set.
We price each Dacorum rear extension on its own footprint and send a fixed, no-obligation quote within one working day. It covers the full drawing pack with free revisions until Dacorum Borough Council approves, and we confirm at the outset whether your extension is permitted development, needs prior approval, or a full application. Call 020 7864 7245 to begin.
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.