Basement in Barnet: Planning Permission Guide
What you need to know about basement extensions in Barnet — planning requirements, costs, and professional guidance.
Based on 16 decided applications in Barnet over 36 months (8 granted, 8 refused). Limited data — treat as indicative.
Barnet has over 15 conservation areas including Hampstead Garden Suburb — a unique 1907 planned community with its own Trust exercising very strict design controls alongside council powers. Other notable conservation areas include Totteridge Village, Mill Hill, and Monken Hadley. The northern fringe borders substantial Green Belt around Totteridge and Arkley. Article 4 Directions cover parts of Hampstead Garden Suburb and other heritage streets.
Personalised odds
5 nearest comparables & refusal reasons for your address.
Get my report — £9See a sample →Recent basement decisions in Barnet
The 5 most recent decided applications. Addresses redacted to postcode area.
Retention of basement and redevelopment and re-provision of new single storey building for flexible floorspace to accommodate cafe/medica…
Implementation of planning permission 22/1629/FUL dated 23.05.2022 for "Demolition of rear storage/retail unit and construction of a ret…
Erection of a two storey detached house with basement and rooms in the roofspace. Associated amenity space, landscaping, off street parki…
Demolition of the existing dwelling and erection of a new two storey dwelling with basement level, rooms in roof space and associated lan…
Creation of new basement with sunken courtyard/patio and associated steps to garden following demolition of existing conservatory. New re…
These are borough-wide. See the 5 nearest to your address.
Get my report — £9Permitted Development Rules
Basement excavation requires a full planning application.
Basement excavation does not have permitted development rights under Part 1 of the GPDO. A full planning application is always required.
Typical Costs in London
Basements are among the most expensive home improvement projects. Costs vary enormously depending on depth, ground conditions, and access.
Cost per m²
construction rate
Typical total
Based on 25–50 m²
Typically includes
Typically excludes
Basement projects are complex and costs vary enormously depending on depth, ground conditions, waterproofing, and access. Professional advice is essential.
Get a personalised cost estimate based on your actual basement dimensions.
Get my estimateWhich Professionals Do You Need?
Basement projects are complex and always require specialist professional input — an architect, structural engineer, and usually a party wall surveyor.
You'll need an architect, a structural engineer, and a party wall surveyor for this project.
Basement projects are complex and require specialist architectural and structural design.
Typical fee: £5,000–£15,000 (Full architectural service)
Basement excavation requires detailed structural engineering for underpinning, retaining walls, and waterproofing.
Typical fee: £2,000–£5,000
Basement excavation almost always triggers the Party Wall Act due to work near neighbouring foundations.
Typical fee: £700–£1,500 (per neighbour)
This guidance is based on a typical semi-detached house with no special constraints. Listed buildings, conservation areas, and attached properties may require additional professional input.
Find out exactly which professionals you need for your basement.
Get personalised guidanceConservation Areas & Listed Buildings
In conservation areas, basement applications receive additional scrutiny. The council will consider the impact on neighbouring properties and the character of the area.
Properties in conservation areas often have reduced permitted development rights. Some project types (like side extensions) lose PD rights entirely. An Article 4 Direction can remove additional PD rights.
Listed buildings (Grade I, II*, or II) have no permitted development rights at all. Any external alteration requires Listed Building Consent in addition to any planning permission. An architect experienced in heritage work is essential.
Check if your property is in a conservation area or has other planning constraints.
Check my propertyFrequently Asked Questions
Just want a quick yes/no for your basement?
Run our free 2-minute check to see whether your project likely qualifies as permitted development in Barnet. For personalised approval odds and nearby comparables, get the £9 report.
Free 2-min check