Side extensions in Hillingdon
33,576 applications since 1977. 22,934 approved and 7,232 refused. Refused: about 1 in 4 here, about 1 in 7 across the councils we cover.
Last updated 9 November 2026.
Without planning permission
- Single storey, no higher than 4 m
- No wider than half the width of the original house
- Not facing a road
England, houses only. Flats, listed buildings, conservation areas and Article 4 directions change this. The full rules.
Year by year
| Year | Applications | Approved | Refused |
|---|---|---|---|
| 2026 | 521 | 367 | 51 |
| 2025 | 695 | 563 | 80 |
| 2024 | 733 | 564 | 98 |
| 2023 | 887 | 637 | 171 |
| 2022 | 972 | 693 | 169 |
| 2021 | 1,194 | 755 | 286 |
| 2020 | 952 | 573 | 279 |
| 2019 | 982 | 595 | 270 |
| 2018 | 1,013 | 590 | 302 |
| 2017 | 981 | 601 | 273 |
| 2016 | 958 | 644 | 220 |
| 2015 | 1,046 | 663 | 265 |
Neighbouring councils
| Council | Approved | Refused | How often |
|---|---|---|---|
| Ealing | 16,200 | 4,787 | about 1 in 4 |
| Harrow | 2,765 | 922 | about 1 in 4 |
| Hounslow | 9,184 | 4,269 | about 1 in 3 |
| Slough | 932 | 182 | about 1 in 6 |
| Spelthorne | 1,207 | 230 | about 1 in 6 |