Two-storey extension drawings for Thornhill homes — bedroom above, living space below, drawn against the 3-metre projection and 7-metre boundary rules and to Sunderland City Council's design guidance, delivered in days and revised free until your decision.
Sunderland City Council granted 91% of the householder planning decisions it made in its latest published year — 4 points above the 87% England-wide householder average. The strong terrace rhythm and consistent brickwork mean front-facing alterations and roof changes are judged against the whole street's uniformity, which is where a policy-literate drawing pack earns its keep. Its dominant Victorian (1837–1901) and Edwardian (1901–1910) 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 Sunderland City Council needs a full application. Thornhill carries at least one Article 4 direction, and conservation areas including Ashbrooke and The Cedars remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Thornhill is determined against an 8-week statutory target.
Thornhill (reddish-brown brick terraces and villas around Langham Tower and St John's Methodist Church), Christ Church (streets radiating from the landmark Victorian church), Ashbrooke edge (high-status villa streets shading into the Ashbrooke conservation area), The Cedars (detached period houses in the designated conservation area) and Park Place (period frontages between the suburb and Mowbray Park) — these are the Thornhill pockets our drawings cover most. Heritage designations here include Ashbrooke and The Cedars. Sunderland City Council weighs each proposal against the Sunderland Core Strategy and Development Plan, where student and HMO conversion pressure near the university triggers the Article 4 controls and strict amenity, refuse and cycle-storage standards. Many Thornhill and Christ Church houses are split into flats and student lets, none of which carry householder permitted-development rights.. On roofs the borough is pitched slate roofs with decorative gables on the terraces and hipped roofs on the larger semis, over late-Victorian brick terraces and villas around Christ Church, substantial Thornhill Terrace houses in rough reddish-brown brick and Edwardian semis and student-let terraces.
Adding at first floor changes the question the case officer asks. A single-storey extension is judged mostly on daylight and garden loss; a two-storey extension is judged on overlooking, bulk against the neighbouring roofline, and whether it reads as part of the house or bolted onto it. Thornhill is largely late-Victorian brick terraces and villas around Christ Church, substantial Thornhill Terrace houses in rough reddish-brown brick and Edwardian semis and student-let terraces, and pitched slate roofs with decorative gables on the terraces and hipped roofs on the larger semis set what a matching roof actually means here.
The permitted-development route exists but is narrow: 3 metres of rear projection, a 7-metre stand-off from the rear boundary, eaves and ridge no higher than the original, and side-facing upper windows obscure-glazed and non-opening below 1.7 metres above floor level. Most two-storey schemes fail one of those, usually the 7-metre boundary rule on a shorter garden, and go in as a full application instead. We establish which route applies before designing, because it changes the drawing set.
The strong terrace rhythm and consistent brickwork mean front-facing alterations and roof changes are judged against the whole street's uniformity. Thornhill sits within Sunderland's protected Victorian suburb alongside the Ashbrooke and The Cedars conservation areas, where the council's Article 4 direction removes permitted-development rights for HMO conversions and some external alterations.
Some two-storey rear extensions are permitted development. You will need a full application to Sunderland City Council if any of these apply:
We set the projection and boundary distance on the site plan, prove the roof-pitch match on the elevations, and specify obscure glazing on the side windows — the three things Sunderland City Council checks first — then submit a validation-complete pack.
Below is Sunderland City Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. Sunderland grants most householder applications, but around Christ Church and Thornhill the conservation-area controls and university-driven conversion pressure are the constraints that shape design most. Two-storey schemes attract more neighbour comment than any other householder work, so the overlooking and daylight case has to be made on the drawings.
Source: MHCLG planning application statistics (householder decisions, England, 1 April 2025 - 31 March 2026). Compare every borough on our London approval-rate league table.
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Across Thornhill, Christ Church and Ashbrooke edge, the schemes that succeed set the first floor back from the ground floor, keep the ridge below the original, and treat the flank wall as blank or obscure-glazed. On late-victorian brick terraces and villas around christ church, matching the eaves line matters more than matching the brick: an extension that carries the existing eaves through reads as original even in a different material.
Student and HMO conversion pressure near the university triggers the Article 4 controls and strict amenity, refuse and cycle-storage standards. We draw the 45-degree daylight test from the neighbour's nearest habitable window, show the window positions in section, and set out the steel and foundation implications early — a two-storey extension changes the load path, so the structural design and the planning design have to be developed together rather than in sequence.
We draw two-storey extensions across Thornhill. A few of the areas where they come up most often:
Two storey extension drawings for Thornhill — reddish-brown brick terraces and villas around Langham Tower and St John's Methodist Church — dimensioned against the 3m and 7m limits and drawn to Sunderland City Council's guidance.
Two storey extension drawings for Christ Church — streets radiating from the landmark Victorian church — dimensioned against the 3m and 7m limits and drawn to Sunderland City Council's guidance.
Two storey extension drawings for Ashbrooke edge — high-status villa streets shading into the Ashbrooke conservation area — dimensioned against the 3m and 7m limits and drawn to Sunderland City Council's guidance.
Two storey extension drawings for The Cedars — detached period houses in the designated conservation area — dimensioned against the 3m and 7m limits and drawn to Sunderland City Council's guidance.
Two storey extension drawings for Park Place — period frontages between the suburb and Mowbray Park — dimensioned against the 3m and 7m limits and drawn to Sunderland City Council's guidance.
The first-floor limits are tighter than the ground-floor ones. This is how the common cases compare.
| Scheme | Permitted development? | Deciding limit | What Sunderland City Council checks |
|---|---|---|---|
| Two-storey rear, 3m projection, 7m+ to boundary | Often yes | 3m projection / 7m boundary | Roof match, side-window glazing |
| Two-storey rear, under 7m to boundary | No — full application | Rear-boundary distance | Overlooking, daylight, garden loss |
| Two-storey side extension | No — full application | Side elevation | Gap to boundary, street rhythm |
| Two-storey wraparound | No — full application | Combined footprint | Bulk, massing, neighbour amenity |
| Any two-storey on designated land | No — full application | Designation | Character and appearance |
Limits from the GPDO 2015, Schedule 2, Part 1, Class A — two-storey rear extension conditions.
A fixed process built around how Sunderland City Council validates and decides two-storey applications.
Send us your Thornhill postcode and garden depth. We measure the 7-metre boundary rule against your plot, confirm designation status, and score your odds against live Sunderland City Council decisions.
We measure the original rear wall, eaves and ridge heights, garden depth and every neighbouring window that faces the site — the inputs the daylight and overlooking case is built from.
Chartered designers develop the two-storey addition to your brief with the roof and eaves resolved, and we coordinate the load path so the structural scheme and the planning scheme are the same building.
We submit the application, manage validation and case-officer queries, and revise the drawings free until Sunderland City Council issues its decision.
Often, but not always. A two-storey rear extension can be permitted development if it projects no more than 3 metres, sits at least 7 metres from the rear boundary, does not exceed the existing eaves and ridge, and has obscure-glazed non-opening side windows below 1.7 metres. In Thornhill, the 7-metre rule is what most commonly forces a full application to Sunderland City Council.
No part of a permitted-development two-storey rear extension may come within 7 metres of the boundary opposite the rear wall of the house. It exists to protect the neighbour behind you from being overlooked at first floor. On shorter Thornhill gardens this is decisive, and we measure it on survey before any design work rather than discovering it at validation. Sunderland City Council is the decision-maker.
Not under permitted development — two-storey side extensions always need a full application to Sunderland City Council. They are assessed on the gap to the boundary, whether the street's rhythm of spaces between houses survives, and whether the extension is subordinate to the original. Setting the first floor back from the front building line and down from the ridge is what usually makes the difference. This applies to your Thornhill address specifically.
Overlooking is the most common objection, and it is answerable on the drawings. We position habitable-room windows away from neighbouring gardens, obscure-glaze and fix shut anything on the flank below 1.7 metres, and show the sight lines in section. Where the geometry is tight, a rooflight or a high-level window gives the same daylight without the mutual overlooking that draws objections. This applies to your Thornhill address specifically. Sunderland City Council is the decision-maker.
Almost certainly. Excavating within 3 metres of a neighbouring structure and building on or up to the boundary both trigger the Party Wall etc. Act 1996, and a two-storey extension usually does both. It is entirely separate from Sunderland City Council's planning decision, so we flag the notice period early and detail the junction on the drawings. This applies to your Thornhill address specifically.
Yes. Adding a floor changes the load path from roof to foundation, so beams, padstones and foundation depths all need designing and calculating for building control. Planning and building regulations are separate consents, and the structural set is what building control assesses — we prepare both so the approved scheme is the buildable one. This applies to your Thornhill address specifically. Sunderland City Council is the decision-maker.
We quote each Thornhill two-storey extension individually, because plot depth, roof form and structural complexity vary house to house, and send a fixed, no-obligation quote within one working day. It covers the drawing pack with free revisions until Sunderland City Council approves. Call 020 7864 7245 to start.
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