Basement in Hillingdon: Planning Permission Guide
What you need to know about basement extensions in Hillingdon — planning requirements, costs, and professional guidance.
Check if your basement qualifiesBasements in Hillingdon at a glance
application fee
weeks typical
Hillingdon has substantial Green Belt covering its western fringes, including Harefield, Ruislip Woods, and the Colne Valley Regional Park. Conservation areas include Harefield Village, Ruislip Village, Ickenham Village, and Uxbridge. Listed buildings cluster around St Mary's Harefield and the historic village cores. Heathrow noise contours affect planning for certain projects in the south. Flood zones apply along the Colne and Frays rivers.
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Approval probability, 5 nearest comparables, refusal reasons — for your specific address.
Recent basement decisions in Hillingdon
The 5 most recent decided applications. Addresses redacted to postcode area.
Details pursuant to the partial discharge of Condition 52 (Fire Strategy - Block C only) of planning permission ref. 1331/APP/2019/2314 d…
Details pursuant to the partial discharge of Condition 29 parts (iv) and (iv) (Contamination - Block B: Blocks B3, B4 and B9 only) and Co…
Details pursuant to the partial discharge of Condition 22 (Rail vibration and ground-borne noise - Block C only) of planning permission r…
Demolition of existing house and erection of a two storey, new build house consisting of 6no. bedrooms with a basement (Amended plans and…
Details pursuant to Condition 24 (service and delivery) of application reference 75127/APP/2023/1646 dated 23-04-24 for 'Minor material a…
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 Hillingdon. For personalised approval odds and nearby comparables, get the full report above.
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