ArchLocal Authority Profile
Slough Borough Council
Adopted Documents We Assess Against
| Document | Type | Version | Monitor Status |
|---|---|---|---|
| Residential Extensions Guidelines SPD | Residential Extensions SPD | Adopted January 2010 | Current checked 4 August 2026 |
Documents are re-checked against the council's own website weekly. A detected change flags "Policy Update Available" for human review — live assessment standards are never replaced automatically.
Slough Borough Council standards at a glance
15 numeric standards taken from Slough Borough Council's own adopted documents, each shown with the paragraph it comes from. Figures differ between councils — these are this one's.
Rear extension depth
Front extension
Side extension form
Amenity neighbouring
Roof alterations
Standards are what the council normally expects, not a guarantee. A scheme outside them can still be approved on its merits, and one inside them can still be refused for another reason.
Authored Policy Library
20 local policy checks, each citation-locked to the adopted document. National policy (NPPF, national space and daylight standards) applies alongside these.
Residential Extensions Guidelines SPD
- Slough REGs EX20 — Rear extension depth (2 checks) For a terraced house in Slough the guideline rear extension depth is 3.65 metres - and if next door sits further back than you, the allowance is measured from their back wall, not yours. For a semi-detached or detached house in Slough the guideline rear extension depth is 4.25 metres.
- Slough REGs EX21 — Rear extension depth Where your rear extension runs along the fence line in Slough, keep it to about 3 metres high there so it does not loom over next door.
- Slough REGs EX25 — Rear extension depth In Slough, past and new rear extensions are added together - the total must stay inside the depth guideline, so an already-extended house has little or no allowance left.
- Slough REGs EX23 — Amenity neighbouring Slough does not permit using the flat roof of a rear extension as a balcony or terrace - it overlooks the neighbours.
- Slough REGs EX2 — Front extension (3 checks) Front additions in Slough are tightly limited - about 2 metres deep at most for a detached house, less for semis and terraces, and never two storeys. On a semi in Slough a front addition should be no deeper than about 1.75 metres. On a terraced house in Slough a front addition should be no deeper than about 1.5 metres.
- Slough REGs EX11 — Side extension form Keep a two-storey side extension in Slough at least 1 metre off the boundary - the gap stops the street turning into one continuous terrace.
- Slough REGs EX18 — Side extension form A two-storey side extension in Slough must keep at least 15 metres from the front of the house it faces.
- Slough REGs EX16 — Amenity neighbouring (2 checks) If your neighbour has a side window lighting a main room, Slough draws a 45-degree line up from its sill - your extension must not cross it unless a daylight report proves their light survives. Slough draw a 45-degree line UP from the sill of your neighbour\x27s side window. Every metre you stand back from it buys you a metre of height. Going above that line needs a daylight report showing their light survives.
- Slough REGs EX26 — Two storey rear Two-storey rear extensions in Slough must pass a 45-degree test from the neighbour's upstairs window, and on a mid-terrace they are effectively ruled out.
- Residential Extensions Guidelines SPD EX48 — Amenity neighbouring (3 checks) A one-bed house in Slough needs 7 metres of garden left behind the extension. On an awkwardly shaped plot they will accept less if the garden still exceeds 40 square metres. A two or three-bed house in Slough needs 9 metres of garden left behind the extension, or 50 square metres if the plot shape makes the depth impossible. A four-bed or larger house in Slough needs 15 metres of garden left. Watch this one if the extension itself adds the fourth bedroom - you get moved into a stricter band by the very works being assessed.
- Residential Extensions Guidelines SPD EX34 — Roof alterations (4 checks) Slough want the top of a dormer half a metre below the main ridge - and dormers on the front will normally be refused outright. Keep the dormer a metre in from each end of the roof slope. The bottom of the dormer sits a metre above the eaves. On a shallow roof this plus the ridge set-down can leave too little headroom for the conversion to work. A Slough dormer can take up half the width of the roof at most, and on a narrow roof the one-metre margins at each end will limit you before the half does.