Loft conversion plans for Hillingdon, £589
Hillingdon says works to roofs or lofts will often need a bat survey. Its well-known Article 4 direction is about rear extensions, not lofts. We sort which rules bite on yours before you spend.
- £439 drawings + £150 survey (£589 total)
- Bat survey flagged early
- Roof plans to council scale
What do loft drawings cost in Hillingdon?
The total is £589: £439 for drawings and submission and £150 for the survey, with no VAT to add. Hillingdon Council’s fee is paid to the council.
In the Hillingdon loft fee
- A roof survey that notes the state of the roof void and any signs of wildlife
- Existing and proposed roof plans at 1:50 or 1:100
- Floor plans, elevations and sections to the council’s scales
- The CIL additional information form and submission to Hillingdon
- A heads-up on whether a bat survey is likely to be requested
Bat surveys and Hillingdon lofts
Hillingdon’s ecological survey item says that proposals involving alterations to roofs or lofts will often need a bat survey, and that smaller schemes close to wildlife sites or green links are more likely to be asked (Hillingdon checklist).
We do not do ecology work. At the roof visit we say whether the house looks likely to be asked, so a qualified ecologist can be booked at the start. For example, an older roof with open eaves near a green link is a likelier case than a recent roof in a built-up street.
What the 4 m direction does and does not cover
Hillingdon’s borough-wide direction ends permitted development for one-storey rear extensions past 4 metres (Hillingdon Article 4). It does not touch Class B roof additions, so a loft outside a conservation area can still be permitted development within the 40 m³ and 50 m³ volume limits.
Hillingdon has 31 conservation areas (Hillingdon conservation areas), where a heritage statement joins the application. Hillingdon decided 637 of 678 householder applications inside 8 weeks in the year to June 2026.
Hillingdon lofts in numbers
- Bat survey
- Hillingdon says proposals altering roofs or lofts will often need one. Hillingdon: local planning validation checklist
- 1:50 or 1:100
- Scales Hillingdon asks for on roof plans, floor plans and elevations. Hillingdon: local planning validation checklist
- 4 m
- Depth limit in Hillingdon’s Article 4 direction, which applies to rear extensions and not to roofs. Hillingdon: Article 4 direction on large rear extensions
- 31
- Conservation areas in Hillingdon. Hillingdon: conservation areas
- 40 m³ / 50 m³
- Permitted roof volume increase: 40 m³ for a terraced house, 50 m³ for other houses. GPDO 2015, Schedule 2, Part 1, Class B: additions to the roof (legislation.gov.uk)
- 637 of 678
- Hillingdon Council householder applications decided within 8 weeks in the year to June 2026, out of all it decided (prior approvals not counted). MHCLG live table PS2, planning application statistics by district, July 2025 to June 2026 (GOV.UK)
- £72.73 per m²
- The Mayor of London’s CIL in Hillingdon (band 2) for permissions granted in 2026, owed only when a scheme is liable for CIL in the first place. Mayoral CIL: annual rate summary for 2026, Table 1 (Greater London Authority)
Hillingdon loft questions
Does my Hillingdon loft need a bat survey?
Often, says Hillingdon. It depends on the roof and how near the house is to wildlife sites or green links.
Does the 4 m Article 4 rule stop a loft?
No. It covers single-storey rear extensions beyond 4 metres, not roof work under Class B.
What plans does Hillingdon want?
Roof plans, floor plans and elevations at 1:50 or 1:100, plus a CIL form and a heritage statement in a conservation area.
How fast does Hillingdon decide?
It decided 637 of 678 householder cases within 8 weeks last year. We cannot promise a date.
Other services people book with this one
Price your Hillingdon loft
Send the address and a roof photo. We say which route fits and quote a fixed price.