01Hillingdon, London
Basement conversion drawings in Hillingdon
Hillingdon's basement policy is firm. It bars basements in listed buildings and basements that run the full width or length of a house, and it does not accept lightwells at the front or side. We check a house against them first, then draw what is left from £1,995 including VAT.
From £1,995 (VAT included)
- MCIAT chartered architectural technologists
- £2m professional indemnity insurance
- LABC Partnered
- ICO registered
02The brief
What the basement policy rules out
The council's Part 2 Development Management Policies do not support a basement that extends the full length or full width of a property, and they require soft landscaping above any basement beyond the house footprint. Lightwells are not acceptable at the front or side. Soil over a basement is typically 450mm soil deep for shrubs.
The policy also requires an assessment of drainage, flooding, groundwater and structural stability. Habitable basements in flood-prone areas are not permitted, and neither are basements in listed buildings.
03The record
Local figures for Hillingdon
| Measure | Value | Period | Source |
|---|---|---|---|
| Basement lightwells are not acceptable at the front or side of a property; soil depth over basements is typically 450mm for shrubs. | 450mm soil | No period | hillingdon.gov.uk, Local Plan Part 2 DM Policies 2020, p.135, paras A1.40-A1.41 |
| Party Wall etc. Act 1996 s6(1), s6(2), s6(5) | Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundations | No period | legislation.gov.uk |
| Approved Document B Vol 1, para 2.16 | Basement storeys with habitable rooms need an escape window or external door, or a protected stair to a final exit | No period | gov.uk |
| Householder: alterations/extensions to a single dwellinghouse, from 1 Apr 2026 | 548 GBP | No period | ribblevalley.gov.uk |
| Domestic gardens share of land (GLUD 2005) | 18.6 % of land that is domestic garden (GLUD 2005) | 2005 | data.london.gov.uk |
| Listed building entries | 436 list entries (Historic England, within the LPA boundary) | No period | planning.data.gov.uk |
| Heritage at Risk entries | 45 Heritage at Risk Register entries within the LPA boundary (Historic England) | No period | planning.data.gov.uk |
| Householder applications granted | 90.2 % | 1 July 2025 - 30 June 2026 | assets.publishing.service.gov.uk |
A blank value means the figure has not been published, not that there are none. Check your own address with the council.
04The drawing
A basement in section
A house and garden over a single-storey basement. The lettered marks show the limits the legend gives.
- A Hillingdon: excavation depth
- 450mm soil
- B Party wall notice for excavation
- Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundations
- C Escape from basement rooms
- Basement storeys with habitable rooms need an escape window or external door, or a protected stair to a final exit
05The detail
Listed houses: a firm no
Historic England records 436 list entries in Hillingdon, with 45 on the Heritage at Risk Register. For a listed house the policy leaves no room for a basement, so we confirm the list entry before any design work. The consent route for other works to such a house is set out under listed building consent drawings in Hillingdon.
In a conservation area the policy also refuses a basement that would harm the area's special architectural or historic character, so we read the street before we draw. If your house is not listed, the design starts from those limits: less than the full width and length, and no lightwell at the front or side.
Assessments and the excavation notice
For full applications, the council's local validation list asks for a Basement Impact Assessment or structural survey where a basement is new or extended. A basement impact assessment is one of our specialist services, quoted after the free constraints check.
The neighbour's side is governed by the Party Wall etc. Act. Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundations. Escape is required for habitable rooms: Basement storeys with habitable rooms need an escape window or external door, or a protected stair to a final exit.
Garden cover and what else to read
In the national land-use survey behind our data (date in the table), 18.6% of the borough's land was domestic garden. The garden above a basement is where the soil-depth rule bites, so our sections show the depth.
The council's householder fee is £548 and 90.2% of householder decisions in the latest published year were grants, a figure that covers every scheme. A roof storey on the same house is limited by its own policy: see mansard roof drawings in Hillingdon, or the basement conversion drawings hub.
06The papers
What the drawings rest on
Listed building consent
07Correspondence
Questions
Can I build a basement under a listed house in Hillingdon?
No. The council's policy does not permit basements in listed buildings. We confirm the list entry before anything else.
Can a basement have a lightwell at the front?
Not in Hillingdon: lightwells are not acceptable at the front or at the side of a property.
How deep must the soil be above a basement?
Typically 450mm soil for shrubs, with soft landscaping above any basement that extends beyond the house footprint.
What does a basement cost to draw?
A fixed fee from £1,995 including VAT. A party wall notice is from £45 per adjoining owner. Council fees are separate.
90.2%
Householder applications granted, Hillingdon, 1 July 2025 - 30 June 2026. Source: assets.publishing.service.gov.uk
08Further reading
Related pages
Other services in Hillingdon
Basement conversion drawings nearby
09Sources
Sources and dates
- hillingdon.gov.uk, retrieved
- legislation.gov.uk, retrieved
- gov.uk, retrieved
- ribblevalley.gov.uk, retrieved
- data.london.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- planning.data.gov.uk, retrieved
- assets.publishing.service.gov.uk, retrieved
Licences
- Contains public sector information licensed under the Open Government Licence v3.0.
- Contains OS data © Crown copyright and database right 2026.
- Contains Historic England data © Historic England 2026. Contains Ordnance Survey data © Crown copyright and database right 2026.
Send us the address of your house.
We look up the conservation area, listing and Article 4 position, then reply with a fixed fee. A message before 3pm is answered the same working day.