Back-of-house extension drawings for Southsea homes — the glazed kitchen-diner across the rear, drawn to Portsmouth City Council's depth and daylight limits, delivered in days and revised free until your decision, with a free approval-odds check first.
Portsmouth City Council granted 88% of the householder planning decisions it made in its latest published year — 1 point above the 87% England-wide householder average. Extreme island density means there is little room to build outward, so most schemes are pushed into the rear and the roof and are judged against tightly packed neighbours, which is where a policy-literate drawing pack earns its keep. Its dominant Georgian (1714–1837), Victorian (1837–1901), Edwardian (1901–1910), interwar (1918–1939) and postwar (1945–1970) housing stock sets the design brief on most streets.
Class A and Class B set the thresholds — a rear dormer to 40m³ on a terrace or 50m³ on a semi or detached, and a single-storey rear extension to 3m on a terrace or 4m on a detached house — beyond which Portsmouth City Council needs a full application. Southsea carries at least one Article 4 direction, and conservation areas including Owen's Southsea, Castle Road and King Street remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Southsea is determined against an 8-week statutory target.
Owen's Southsea (Thomas Ellis Owen's mid-Victorian stucco villas around Queens Crescent), Castle Road (fine-grained Regency and early-Victorian terraces near the Common), Elm Grove (grand Victorian terraces along the spine toward the seafront), Albert Road (the shopping and cafe strip fronted by tall Victorian houses), Somers Town (postwar and interwar estate housing on the northern edge) and Kings Road (Victorian terraces and mansion flats near Palmerston Road) — these are the Southsea pockets our drawings cover most. Heritage designations here include Owen's Southsea, Castle Road, King Street, Stanley Street and The Terraces. Portsmouth City Council weighs each proposal against the Portsmouth Local Plan and the council's Houses in Multiple Occupation SPD, where the city-wide Article 4 direction and the HMO SPD steer student-let conversions near the University through full planning control. Much of central Southsea has already been split into converted flats and maisonettes, which carry no householder permitted-development rights of their own.. On roofs the borough is pitched slate roofs on the bay-fronted terraces and shallow parapet and valley roofs behind Owen's stucco frontages, over Thomas Ellis Owen's stucco villas and terraces, bay-fronted Victorian and Edwardian terraces and converted flats and maisonettes.
The rear extension is the workhorse of Southsea home improvement — it is how a dark back kitchen becomes an open family room facing the garden. Because the borough is built largely from Thomas Ellis Owen's stucco villas and terraces, bay-fronted Victorian and Edwardian terraces and converted flats and maisonettes, most back walls sit close to a neighbour on at least one side, and that proximity, not the design, is what Portsmouth City Council scrutinises. The council reads the proposal against the Portsmouth Local Plan and the council's Houses in Multiple Occupation SPD, 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. Extreme island density means there is little room to build outward, so most schemes are pushed into the rear and the roof and are judged against tightly packed neighbours, so the rear elevation is composed around it rather than corrected after an objection.
Where the property sits in a conservation area — Owen's Southsea, Castle Road, King Street, Stanley Street and The Terraces among Southsea's — the larger-home extension route is switched off and even a modest rear addition needs consent. Portsmouth operates a city-wide Article 4 direction removing permitted-development rights for the change of family houses to small (C4) houses in multiple occupation, so on Southsea's dense terraced streets near the University any HMO conversion needs a full planning application rather than being automatic. We confirm the designation before the survey.
Many single-storey rear extensions in Southsea are permitted development and need no application. You will normally need to apply to Portsmouth 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 Portsmouth 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 Portsmouth City Council's real householder decision record, taken from official planning statistics and refreshed as new data lands. Portsmouth consents roughly seven or eight in ten householder schemes, but on Southsea's stucco villa streets and packed terraces the deciding issues are heritage grain, HMO saturation and the sheer proximity of neighbours. 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 Owen's Southsea, Castle Road and Elm Grove, 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 thomas ellis owen's stucco villas and terraces, 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 city-wide Article 4 direction and the HMO SPD steer student-let conversions near the University through full planning control. We keep the extension inside the daylight splays, set any glazed roof below the first-floor cill, and retain the garden depth Portsmouth 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 Southsea back-of-house projects come up most often:
Rear extension drawings for Owen's Southsea's Thomas Ellis Owen's mid-Victorian stucco villas around Queens Crescent — depth-checked, daylight-tested and drawn to Portsmouth City Council's guidance.
Rear extension drawings for Castle Road's fine-grained Regency and early-Victorian terraces near the Common — depth-checked, daylight-tested and drawn to Portsmouth City Council's guidance.
Rear extension drawings for Elm Grove's grand Victorian terraces along the spine toward the seafront — depth-checked, daylight-tested and drawn to Portsmouth City Council's guidance.
Rear extension drawings for Albert Road's the shopping and cafe strip fronted by tall Victorian houses — depth-checked, daylight-tested and drawn to Portsmouth City Council's guidance.
Rear extension drawings for Somers Town's postwar and interwar estate housing on the northern edge — depth-checked, daylight-tested and drawn to Portsmouth City Council's guidance.
Rear extension drawings for Kings Road's Victorian terraces and mansion flats near Palmerston Road — depth-checked, daylight-tested and drawn to Portsmouth City Council's guidance.
How far you can extend at the back in Southsea depends on your house type and the route you take. This is how the options compare.
| Route | Depth allowed | Consent needed | What Portsmouth 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 Owen's Southsea and Castle Road and Article 4 streets need a full application.
A fixed process built around how Portsmouth City Council validates and decides rear-extension applications — most drawings are submission-ready within seven days of survey.
Send us your Southsea 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 Portsmouth 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 Portsmouth 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 Portsmouth 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 Southsea. You will need to involve Portsmouth 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 Owen's Southsea and Castle Road, 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 Portsmouth 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 Southsea's conservation areas.
It is the daylight test Portsmouth 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 Southsea address specifically.
A two-storey rear extension almost always needs a full householder application to Portsmouth 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 Southsea 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 Portsmouth 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 Southsea address specifically.
We price each Southsea 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 Portsmouth 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.
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.