Do I Need Planning Permission for a Two Storey Extension?
Two storey rear extensions almost always need planning permission. PD rights for two storey work are very limited — the depth is restricted to 3m (all house types), and the design must not extend above the existing ridge. Most homeowners need a full planning application.
PD rules for two storey extensions
PD rules for two storey extensions
Technically, PD allows two storey rear extensions under strict conditions: maximum 3m depth from the original rear wall, at least 7m between the rear wall of the extension and the rear boundary, maximum eaves/ridge height matching the existing house, and no closer to the boundary than 2m. In practice, these limits are so tight that most two storey projects exceed them and need planning.
The planning application process
A householder planning application (£258 council fee) takes 6–10 weeks. For two storey extensions, officers pay close attention to: overlooking (new upper windows facing neighbours), loss of daylight (the 45-degree and 25-degree rules), bulk and mass (is the extension overbearing?), and design quality (does it look like part of the original house?).
Improving approval chances
Key design principles: set the extension back from the side wall to reduce bulk, lower the ridge below the existing ridge, use matching materials, position upper windows to avoid overlooking (obscure glazing, high-level windows, or rear-facing only), and comply with the 45-degree rule for neighbour daylight. Our designs address all of these systematically.
Common questions
Frequently asked questions
Extension guides
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Planning permission for two storey extensions — PD limits, application requirements, neighbour impact, and what to expect from the process.
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