Offline Property Intelligence

• Offline mode cannot retrieve fresh planning applications, live constraint changes, Street View imagery or policy updates made after the bundled snapshot.

• No offline answer is a certificate of lawfulness, planning decision, valuation, legal/title opinion or technical design approval.

An upward extension may have a prior-approval route — but only if every Class AA limit is met

Class AA can permit one extra storey above a one-storey house or up to two above a house of two or more storeys. It is not an automatic right: construction date, designations, previous upward extensions, height, roof form, materials, side windows and neighbour impacts all matter.

Likely route

England GPDO Part 1 Class AA — prior approval before work starts; full householder planning if a Class AA limitation fails.

Unknowns to prove

• — Whether the house has previously been enlarged upward above the original dwellinghouse.
• — Floor-to-ceiling height of the proposed storey compared with the shortest existing principal-part storey.
• — For attached houses, the statutory relationship to the highest part of adjoining/row roofs.
• — Whether prior approval would identify unacceptable neighbour amenity, privacy, external appearance or other prescribed impacts.

Street-scene design test

• — Compare the proposed eaves and ridge line with the two or three buildings on either side, not just with the subject building.
• — Match or deliberately respond to the prevailing roof form, pitch, parapet/mansard treatment and storey rhythm visible in the street.
• — Show the proposal in a context elevation so the officer can see height, massing, setbacks and the roof silhouette in one drawing.
• — Keep materials, window proportions, bay rhythm and architectural detailing coherent with the building and the wider street unless a clearly justified contemporary contrast is intended.
• — Test overlooking, side-facing windows, daylight/sunlight, outlook and overbearing impact against immediate neighbours.
• — Show how parking, cycle storage, refuse, servicing, access, trees and landscaping work after the extra floorspace or dwellings are added.

How to improve approval prospects

1. 1. Prepare existing/proposed elevations and a street context elevation showing the new ridge/eaves against neighbouring properties.
2. 2. For a Class AA route, demonstrate every statutory limitation explicitly in a compliance schedule rather than relying on a generic planning statement.
3. 3. Use matching/sympathetic external materials, retain a coherent roof pitch and avoid side windows where the Class AA condition prevents them.
4. 4. Address neighbour amenity, overlooking, privacy, daylight and the external appearance of the dwellinghouse in the prior-approval submission.
5. 5. If Class AA is unavailable, pivot to a full householder application and use the NPPF support for well-designed upward extensions that fit the prevailing form and street scene.