Back-of-house extension drawings for Castle homes — the glazed kitchen-diner across the rear, drawn to Cambridge City Council's depth and daylight limits, delivered in days and revised free until your decision, with a free approval-odds check first.
Cambridge City Council granted 90% of the householder planning decisions it made in its latest published year — 3 points above the 87% England-wide householder average. The Cambridge skyline guidance protects long views from Castle Hill across the historic city, which is where a policy-literate drawing pack earns its keep. Its dominant Georgian (1714–1837), Victorian (1837–1901) and Edwardian (1901–1910) housing stock sets the design brief on most streets.
Under Class B, a rear dormer stays permitted development up to 40m³ of added roof volume on a terrace or 50m³ on a semi-detached or detached house, while Class A allows a single-storey rear extension of 3m beyond the original rear wall on a terrace and 4m on a detached house before a full application is needed. Castle carries at least one Article 4 direction, and conservation areas including Castle and Victoria Road, Central and Storey's Way remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Castle is determined against an 8-week statutory target.
Castle Hill (Georgian and Victorian houses beside the Norman castle mound and Kettle's Yard), Victoria Road (Victorian terraces running north from the historic core), Storey's Way (spacious Arts-and-Crafts villas laid out by St John's College), Mount Pleasant (elevated Victorian and Edwardian houses above the city) and Huntingdon Road (large detached and academic houses on the northern approach) — these are the Castle pockets our drawings cover most. Heritage designations here include Castle and Victoria Road, Central and Storey's Way. Cambridge City Council weighs each proposal against the Cambridge Local Plan 2018 and the emerging Greater Cambridge Local Plan, where the planned Arts-and-Crafts layout of Storey's Way constrains infill and the scale of extensions. Several of the larger Castle Hill and Huntingdon Road houses have been converted to flats, which carry no householder permitted-development rights.. On roofs the borough is pitched slate roofs on the Georgian and Victorian houses and gabled and hipped tile roofs on the Arts-and-Crafts villas, over Georgian and early-Victorian houses on Castle Hill, Victorian terraces along Victoria Road and Arts-and-Crafts villas on Storey's Way.
The rear extension is the workhorse of Castle home improvement — it is how a dark back kitchen becomes an open family room facing the garden. Because the borough is built largely from Georgian and early-Victorian houses on Castle Hill, Victorian terraces along Victoria Road and Arts-and-Crafts villas on Storey's Way, most back walls sit close to a neighbour on at least one side, and that proximity, not the design, is what Cambridge City Council scrutinises. The council reads the proposal against the Cambridge Local Plan 2018 and the emerging Greater Cambridge Local Plan, 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. The Cambridge skyline guidance protects long views from Castle Hill across the historic city, so the rear elevation is composed around it rather than corrected after an objection.
Where the property sits in a conservation area — Castle and Victoria Road, Central and Storey's Way among Castle's — the larger-home extension route is switched off and even a modest rear addition needs consent. The Castle and Victoria Road conservation area — appraised in 2012 with a 2013 addendum — covers Castle Hill and its surrounds, adjoining the Central and Storey's Way areas, and Article 4 directions remove permitted-development rights across these streets. We confirm the designation before the survey.
Many single-storey rear extensions in Castle are permitted development and need no application. You will normally need to apply to Cambridge City 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 Cambridge City 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 Cambridge City Council's real householder decision record, taken from official planning statistics and refreshed as new data lands. Cambridge approves around 90% of applications, but the Castle and Victoria Road conservation area and the protected Castle Hill views are the decisive factors here. 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 Castle Hill, Victoria Road and Storey's Way, 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 georgian and early-victorian houses on castle hill, 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 planned Arts-and-Crafts layout of Storey's Way constrains infill and the scale of extensions. We keep the extension inside the daylight splays, set any glazed roof below the first-floor cill, and retain the garden depth Cambridge City 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 Castle back-of-house projects come up most often:
Rear extension drawings for Castle Hill's Georgian and Victorian houses beside the Norman castle mound and Kettle's Yard — depth-checked, daylight-tested and drawn to Cambridge City Council's guidance.
Rear extension drawings for Victoria Road's Victorian terraces running north from the historic core — depth-checked, daylight-tested and drawn to Cambridge City Council's guidance.
Rear extension drawings for Storey's Way's spacious Arts-and-Crafts villas laid out by St John's College — depth-checked, daylight-tested and drawn to Cambridge City Council's guidance.
Rear extension drawings for Mount Pleasant's elevated Victorian and Edwardian houses above the city — depth-checked, daylight-tested and drawn to Cambridge City Council's guidance.
Rear extension drawings for Huntingdon Road's large detached and academic houses on the northern approach — depth-checked, daylight-tested and drawn to Cambridge City Council's guidance.
How far you can extend at the back in Castle depends on your house type and the route you take. This is how the options compare.
| Route | Depth allowed | Consent needed | What Cambridge City 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 Castle and Victoria Road and Central and Article 4 streets need a full application.
A fixed process built around how Cambridge City Council validates and decides rear-extension applications — most drawings are submission-ready within seven days of survey.
Send us your Castle 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 Cambridge City 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 Cambridge City 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 Cambridge City 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 Castle. You will need to involve Cambridge City 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 Castle and Victoria Road and Central, 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 Cambridge City 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 Castle's conservation areas.
It is the daylight test Cambridge City 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. This applies to your Castle address specifically.
A two-storey rear extension almost always needs a full householder application to Cambridge City 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. This applies to your Castle address specifically.
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 Cambridge City Council's planning decision. We flag it early and can prepare the drawings a party-wall surveyor needs alongside the planning set. This applies to your Castle address specifically.
We price each Castle 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 Cambridge City 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.
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