2607-0001 - AUTOPLAN

Single-storey extension Larger Home Extension prior approval assessed

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View the current brief emitted 6 Aug 2026, 12:56 a.m. · schema 1.4

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Constraints 4

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Previous extensions count against the allowance, and it is measured against the *original* dwelling as built - not the house as you bought it. This needs calculating before any PD assumption holds.

GPDO 2015 Sch.2 Part 1 Class A.1(b)-(f)

Habitable room windows face the proposal, so the 45-degree test - and the 25-degree vertical test at first floor - both apply. Expect the massing to be cut back on that side.

BRE 209 Site Layout Planning for Daylight and Sunlight; local SPD 45-degree code

For information

Beyond the standard permitted development depth this becomes a Larger Home Extension prior approval - up to 6m on an attached house or 8m detached. It runs a neighbour consultation scheme, which is 42 days before you can start.

GPDO 2015 Sch.2 Part 1 Class A.4

Shared walls mean a Party Wall Act notice: two months minimum before work can start. It constrains the programme, not the design, but it is the constraint that most often delays a start on site.

Party Wall etc. Act 1996 s.3, s.6