Orangery and conservatory drawings for Spelthorne homes — checked against the Class A rear limits and the 30m² building-regulations exemption, drawn to Spelthorne Borough Council's guidance and revised free until your decision.
Spelthorne Borough 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 borough is flat and low-lying, so severe Thames flood risk — with functional floodplain in Flood Zone 3b an absolute constraint — dominates where and how development can go, which is where a policy-literate drawing pack earns its keep. Its dominant 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 Spelthorne Borough Council needs a full application. Spelthorne carries at least one Article 4 direction, and conservation areas including Staines, Laleham and Lower Sunbury remove those rights outright, so we confirm your exact address before a line is drawn. A validated householder application in Spelthorne is determined against an 8-week statutory target.
Staines-upon-Thames (the main town with Victorian, Edwardian and twentieth-century housing and a riverside conservation area), Ashford (largely interwar and postwar suburban semis and detached commuter housing), Sunbury-on-Thames (riverside period and suburban housing with the Lower Sunbury conservation area along the Thames), Shepperton (a historic Church Square village core and riverside studio-town character), Laleham (a small Thames-side conservation village of period and detached riverside houses) and Stanwell (mixed postwar estate housing near Heathrow with its own conservation area) — these are the Spelthorne pockets our drawings cover most. Heritage designations here include Staines, Laleham, Lower Sunbury, Shepperton, Lower Halliford and Stanwell. Spelthorne Borough Council weighs each proposal against the Spelthorne Local Plan 2024–2039 (adopted March 2026), where Metropolitan Green Belt covers much of the undeveloped borough, with only weakly-performing parcels considered for release. Converted flats and maisonettes are common around Staines and Ashford, and none of them hold householder permitted-development rights.. On roofs the borough is hipped roofs on the interwar and postwar semis and dual-pitch tiled roofs on the riverside period houses, over interwar and postwar semi-detached and detached suburban housing across Ashford, Sunbury and Stanwell, Victorian, Edwardian and twentieth-century housing around Staines-upon-Thames, riverside period and detached villas along the Thames at Laleham, Shepperton and Lower Sunbury and historic village and church cores.
The difference is not marketing. A conservatory is predominantly glazed — at least three quarters of the roof and half of the walls — which is what earns it the building-regulations exemption. An orangery has a solid masonry perimeter with a glazed lantern set into a flat roof, so it usually reads as a conventional extension for building control and has to meet Part L thermal standards, Part A structure and Part B fire like any other room.
Both are judged the same way for planning: as rear extensions, against the Class A depth, height and eaves limits, and against the Spelthorne Local Plan 2024–2039 (adopted March 2026). Spelthorne is largely interwar and postwar semi-detached and detached suburban housing across Ashford, Sunbury and Stanwell, Victorian, Edwardian and twentieth-century housing around Staines-upon-Thames, riverside period and detached villas along the Thames at Laleham, Shepperton and Lower Sunbury and historic village and church cores, and the design question is usually whether the glazing reads as a lightweight addition to that stock or as a bolted-on conservatory kit. On period houses, an orangery with a properly proportioned lantern almost always sits better than a full-height glazed box.
In conservation areas such as Staines and Laleham, rear glazing is assessed on visibility from the street and on the effect on the rear elevation's character. Spelthorne has brought in a borough-wide Article 4 direction, phased in across all wards during 2025 and 2026, removing the permitted right to convert a dwelling into a small HMO so that these conversions now need planning permission everywhere in the borough.
Many conservatories are permitted development. You will need an application to Spelthorne Borough Council where any of these apply:
We check the scheme against the Class A planning limits and against the building-regulations exemption at the same time, so you know before committing whether you are building an exempt conservatory or a fully regulated room.
Below is Spelthorne Borough Council's real householder decision record, drawn from official planning statistics and refreshed as new data lands. Spelthorne grants a little above the national average of applications, with Thames flood risk and green-belt containment the constraints that shape most larger schemes. Glazed rear additions are judged on depth, eaves height and how the glazing meets the existing elevation.
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 Staines-upon-Thames, Ashford and Sunbury-on-Thames, the schemes that succeed keep the eaves below the neighbour's ground-floor cill line, set the glazing back from the boundary, and use a solid parapet or brick perimeter to tie the addition into the house. On interwar and postwar semi-detached and detached suburban housing across ashford, sunbury and stanwell, a lantern set in a flat roof usually reads better than a pitched glazed roof, and it avoids the summer overheating that makes full conservatories unusable for months a year.
The borough is flat and low-lying, so severe Thames flood risk — with functional floodplain in Flood Zone 3b an absolute constraint — dominates where and how development can go. The decision worth making early is whether to keep the separating doors. Keeping them preserves the building-regulations exemption but leaves you with a room that is not part of the house; removing them creates one continuous space but brings the whole addition inside Part L, which changes the glazing specification and usually the heating design too. We set out both versions before you commit.
We draw glazed rear additions across Spelthorne. A few of the areas where they come up most often:
Orangery and conservatory drawings for Staines-upon-Thames — the main town with Victorian, Edwardian and twentieth-century housing and a riverside conservation area — checked against the Class A limits and drawn to Spelthorne Borough Council's guidance.
Orangery and conservatory drawings for Ashford — largely interwar and postwar suburban semis and detached commuter housing — checked against the Class A limits and drawn to Spelthorne Borough Council's guidance.
Orangery and conservatory drawings for Sunbury-on-Thames — riverside period and suburban housing with the Lower Sunbury conservation area along the Thames — checked against the Class A limits and drawn to Spelthorne Borough Council's guidance.
Orangery and conservatory drawings for Shepperton — a historic Church Square village core and riverside studio-town character — checked against the Class A limits and drawn to Spelthorne Borough Council's guidance.
Orangery and conservatory drawings for Laleham — a small Thames-side conservation village of period and detached riverside houses — checked against the Class A limits and drawn to Spelthorne Borough Council's guidance.
Orangery and conservatory drawings for Stanwell — mixed postwar estate housing near Heathrow with its own conservation area — checked against the Class A limits and drawn to Spelthorne Borough Council's guidance.
The planning test is the same for both. The building-regulations test is not.
| Structure | Planning route | Building regulations | Practical effect |
|---|---|---|---|
| Conservatory under 30m², doors retained | Class A rear extension limits | Largely exempt | Cheaper build, unheated in winter |
| Conservatory, doors removed | Class A rear extension limits | Part L applies in full | Continuous space, higher spec glazing |
| Orangery with solid perimeter and lantern | Class A rear extension limits | Fully regulated | Usable year round, better on period houses |
| Any of the above beyond the depth limits | Full householder application | As above | 8-week determination |
| Any of the above on designated land | Full householder application | As above | Design and visibility assessed |
Planning limits from the GPDO 2015, Schedule 2, Part 1, Class A; exemption criteria from the Building Regulations 2010, Schedule 2, Class 7.
A fixed process covering both consents, because they pull in different directions.
Send us your Spelthorne postcode and house type. We confirm the Class A limits that apply, check designation status, and score your odds against live Spelthorne Borough Council decisions.
We measure the rear elevation, eaves and ground levels, and the neighbouring boundary — the numbers that decide both the projection limit and the 2-metre eaves rule.
Chartered designers develop the orangery or conservatory to your brief, and we set out clearly whether it stays inside the building-regulations exemption or becomes a fully regulated room.
We submit the certificate or application, manage validation and officer queries, and revise free until Spelthorne Borough Council decides.
Often not. A conservatory is treated as a rear extension, so it can be permitted development within the Class A limits — 3 metres of projection on a terrace or semi, 4 metres on a detached house, with eaves under 3 metres where it sits within 2 metres of a boundary. In Spelthorne you will need an application to Spelthorne Borough Council beyond those limits, and on designated land such as Staines and Laleham.
A conservatory is largely exempt if it is under 30 square metres, at ground level, separated from the house by external-quality doors, and has at least 75% of its roof and 50% of its walls glazed. Glazing, electrics and any drainage work still have to comply. Remove the separating doors and the exemption falls away — the space becomes part of the house and Part L thermal standards apply. This applies to your Spelthorne address specifically. Spelthorne Borough Council is the decision-maker.
For planning, none — both are rear extensions assessed against the same Class A limits by Spelthorne Borough Council. The difference is in building control: an orangery's solid perimeter and flat roof with a lantern usually means it fails the glazing test for exemption, so it is fully regulated. That is why an orangery costs more to build but is comfortable in January.
Usually yes at the rear, though permitted-development rights are narrower on designated land and an Article 4 direction can remove them entirely. The assessment turns on whether the addition is visible from the street and how it meets the original rear elevation. A restrained orangery in matching brick with a lantern is consistently easier to get through than a proprietary glazed conservatory. This applies to your Spelthorne address specifically. Spelthorne Borough Council is the decision-maker.
A fully glazed roof will, unless it is specified for it. That is the practical reason most of our clients end up building an orangery instead: a solid insulated roof perimeter with a lantern gives daylight without the greenhouse effect, and keeps the space usable across the year. We raise it at design stage because it is much cheaper to solve on paper than after the build. This applies to your Spelthorne address specifically. Spelthorne Borough Council is the decision-maker.
If you excavate foundations within 3 metres of a neighbouring structure and deeper than its foundations, or build on the boundary itself, the Party Wall etc. Act 1996 applies and notice must be served. That is separate from Spelthorne Borough Council's planning decision. We flag it at design stage so the notice period does not delay the start on site.
We quote each Spelthorne orangery or conservatory individually, because the structure and the roof form change the work considerably, and send a fixed, no-obligation quote within one working day. It covers the full drawing pack with free revisions until Spelthorne Borough Council approves. Call 020 7864 7245 to start.
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