About the Botwell: Thorn EMI Conservation Area
The Botwell: Thorn EMI Conservation Area covers about 6.0 hectares and was designated by London Borough of Hillingdon in 1988. Inside the boundary is 1 listed building, all Grade II. 4 Article 4 directions over the area remove further householder rights, on top of the conservation area limits below.
What changes inside the conservation area
Conservation areas are “Article 2(3) land”. You keep most permitted development rights, but these are removed or tightened.
- Rear extensionElsewhere: 3 m · 6 m with PANo 6 m / 8 m prior approval
- Two-storey extensionElsewhere: 3 mNeeds planning permission
- Side extensionElsewhere: Half the widthNeeds planning permission
- Loft conversionElsewhere: 50 m³Needs planning permission
- Garden roomElsewhere: 2.5 m high by boundariesNot beside the house
- PorchElsewhere: 3 m²Same limits
- Solar panelsElsewhere: 0.2 m projectionSame limits
- Air source heat pumpElsewhere: 1 unitNot facing the road
- Fences, walls and gatesElsewhere: 2 m · 1 m by a roadSame limits
- External claddingElsewhere: Matching materialsNeeds planning permission
- Tree workElsewhere: No notice6 weeks’ notice to the council
- Demolition (over 115 m³)Elsewhere: AllowedNeeds planning permission
Limits for a semi-detached house under the GPDO 2015. An Article 4 direction can remove more.
Article 4 directions here
These overlap the conservation area. Householder directions remove more of the rights above; change-of-use ones don’t affect extending a house.
- Changes of use from commercial, business and service uses to dwellinghousesChange of use
- Residential extensionsHouseholder works
- Construction of new dwellinghouses in employment areasHouseholder works
- Construction of new dwellinghouses in employment areasHouseholder works
- Construction of new dwellinghouses in employment areasHouseholder works
Listed buildings in the conservation area
Any work affecting these needs listed building consent, inside or out. Each links to its entry on the National Heritage List.
- Enterprise HouseGrade II
Nearby conservation areas
Boundary and listed buildings from London Borough of Hillingdon and Historic England via planning.data.gov.uk (OGL). Guidance only — not an official council check.