Solar panels, heat pumps and insulation in Cobham conservation area
In the Cobham conservation area (Gravesham), external wall insulation needs planning permission, and so does an air source heat pump on a wall or roof facing the road; one at the back or side, internal and loft insulation and solar panels on a roof slope normally do not. An Article 4 direction published by Gravesham covers this area and removes permitted development rights for replacement windows and doors, and other alterations to the house, alterations to the roof (e.g. rooflights), painting the outside, so there these need planning permission too. The area has 28 listed buildings; on a listed building solar panels and heat pumps are not permitted development at all and need planning permission and listed building consent. 100 homes inside the boundary have an energy certificate: 40.0% are solid-wall homes with no wall insulation, 1.0% heat with a gas boiler and 83.0% are rated D–G; 13 have a heat pump. EPC register November 2026; rules as at 21 October 2026.
Data: EPC register November 2026 (latest certificate per home), conservation area boundaries 3 November 2026, permitted development rules as at 21 October 2026 · calculated 5 November 2026 · Methodology and sources
100homes with an energy certificate
40.0%solid walls, no insulation
1.0%heated by a gas boiler
13heat pumps
Article 4: An Article 4 direction published by Gravesham covers this area and removes permitted development rights for replacement windows and doors, and other alterations to the house, alterations to the roof (e.g. rooflights), painting the outside, so there these need planning permission too. (Cobham - Ar/09/3)
What needs planning permission in Cobham
Work (house, not listed)
In a conservation area
Rule
Air source heat pump on a wall or roof facing the road, or nearer the road than the house
Planning permission needed
Part 14 Class G, G.1(j)
Air source heat pump at the back or side (outdoor unit up to 1.5 m³, MCS Planning Standards, one per house — two on a detached house)
No permission needed (permitted development)
Part 14 Class G
Solar panels on a pitched roof (up to 0.2 m proud, not above the ridge)
No permission needed (permitted development)
Part 14 Class A, A.2(c)
Solar panels on a wall, balcony or roof enclosure facing the road
Planning permission needed
Part 14 Class A, A.2(e)
Solar panels on a flat roof (up to 0.6 m above the roof)
Replacement windows and doors of similar appearance
Planning permission needed (an Article 4 direction here removes this right)
Part 1 Class A, A.3(a)
Listed buildings: 28 in the area (grade I: 2, II*: 2). The table is for houses that are not listed: on a listed building, solar panels and air source heat pumps are not permitted development at all (they need planning permission), and any of these works needs listed building consent.
Flats: 8% of the certified homes here are flats or maisonettes. Homes in a block of flats have no householder rights for alterations; heat pumps and solar have their own, tighter rules for blocks of flats.
The homes in the area (latest certificate per home, n = 100)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
40
40.0%
Cavity wall, filled
26
26.0%
Cavity wall, unfilled
15
15.0%
Modern wall (U-value from the design)
8
8.0%
Cavity wall, insulated (as built or unspecified)
3
3.0%
Solid wall, internal insulation
3
3.0%
Timber frame
3
3.0%
Other or not known
1
1.0%
Solid wall, partly insulated
1
1.0%
Heating
Homes
Share
Oil
56
56.0%
Electric (storage heaters, panels, boiler)
19
19.0%
Heat pump
13
13.0%
LPG
9
9.0%
Solid fuel (wood, coal)
2
2.0%
Gas boiler
1
1.0%
Loft / roof insulation
Homes
Share
No insulation
15
15.0%
Under 200 mm
34
34.0%
200 mm or more
33
33.0%
Insulated (depth not recorded)
8
8.0%
Flat or other home above
4
4.0%
Other
6
6.0%
Windows
Homes
Share
Double glazed
72
72.0%
Single glazed
21
21.0%
Secondary glazing
7
7.0%
BDEF
Energy rating: B 13 (13.0%) · C 4 (4.0%) · D 16 (16.0%) · E 41 (41.0%) · F 20 (20.0%) · G 6 (6.0%). Houses and bungalows: 92% of the homes; solar panels on 9.0% of the certificates. Most common build period on the certificates: before 1900. Designated: 1 January 1970.
Compared with Gravesham and England
Share of homes
Cobham
All 23 areas in Gravesham
England
Solid walls, no insulation
40.0%
59.6%
48.7%
Gas boiler
1.0%
68.8%
66.4%
Rated D–G
83.0%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 44% of these are from 2020 or later (latest 6 August 2026). “No insulation (assumed)” is the assessor's default for older walls.
The rules are England's national permitted development rules (General Permitted Development Order 2015, Schedule 2, as at 21 October 2026). They do not cover building regulations or a council's own conditions. This is not a planning decision: ask Gravesham if in doubt.
Boundary: Gravesham Borough Council via planning.data.gov.uk (entity 44016172, reference 2008/12/CONARA, 45.2 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.