Single-storey, double-storey, rear and side extension drawings for Southsea homes — measured to Portsmouth City Council's design guidance, delivered in days and revised free until your decision, with a free approval-odds check before you commit.
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.
Southsea homes come in a handful of recurring shapes, and each one points to a different extension. 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, 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. Portsmouth City Council judges every one of them against the Portsmouth Local Plan and the council's Houses in Multiple Occupation SPD, 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. 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 we design around it from the first sketch rather than discover it at validation.
Southsea also protects whole streets — Owen's Southsea, Castle Road, King Street, Stanley Street and The Terraces among them. 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. 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 Southsea 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 Portsmouth City Council if any of these apply:
We draw the footprint, the ridge and eaves heights and the neighbours' daylight on the page — the relationships Portsmouth City 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 Portsmouth City Council's real householder decision record, drawn 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. 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 Owen's Southsea, Castle Road and Elm Grove, 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 thomas ellis owen's stucco villas and terraces, a side-return infill frequently pairs with it to square off the plan; on wider converted flats and maisonettes, a two-storey side or rear extension can add a bedroom above without swallowing the garden.
The city-wide Article 4 direction and the HMO SPD steer student-let conversions near the University through full planning control. 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 Portsmouth City 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 Southsea projects come up most often:
Extension drawings for Owen's Southsea's Thomas Ellis Owen's mid-Victorian stucco villas around Queens Crescent — footprint-checked, daylight-tested and drawn to Portsmouth City Council's guidance.
Extension drawings for Castle Road's fine-grained Regency and early-Victorian terraces near the Common — footprint-checked, daylight-tested and drawn to Portsmouth City Council's guidance.
Extension drawings for Elm Grove's grand Victorian terraces along the spine toward the seafront — footprint-checked, daylight-tested and drawn to Portsmouth City Council's guidance.
Extension drawings for Albert Road's the shopping and cafe strip fronted by tall Victorian houses — footprint-checked, daylight-tested and drawn to Portsmouth City Council's guidance.
Extension drawings for Somers Town's postwar and interwar estate housing on the northern edge — footprint-checked, daylight-tested and drawn to Portsmouth City Council's guidance.
Extension drawings for Kings Road's Victorian terraces and mansion flats near Palmerston Road — footprint-checked, daylight-tested and drawn to Portsmouth City Council's guidance.
The right extension in Southsea 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 Portsmouth City 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 Owen's Southsea and Castle Road and Article 4 directions can remove permitted-development rights.
A fixed process built around how Portsmouth City Council validates and decides householder extension applications — most drawings are submission-ready within seven days of survey.
Tell us your Southsea 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 Portsmouth City 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 Portsmouth City 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 Portsmouth City 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 Southsea you will need to apply to Portsmouth City 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 Owen's Southsea and Castle Road.
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 Portsmouth City Council and a neighbour-consultation period, and it does not apply on designated land such as Southsea'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 Portsmouth City 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. This applies to your Southsea address specifically.
A householder planning application in Southsea 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. Portsmouth City 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 Portsmouth City Council's building control or an approved inspector can sign the work off. This applies to your Southsea address specifically.
Every house and brief is different, so we price each Southsea extension individually and send a fixed, no-obligation quote back within one working day. It covers the full drawing pack with free revisions until Portsmouth City 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.