Two-storey and first-floor extensions in Hillingdon
Hillingdon approved 618 of the 817 planning applications for two-storey and first-floor extensions it decided in the last five years (76%), and the typical decision took 57 days.
London Borough of Hillingdon · planning applications received Oct 2021 to Oct 2026 · updated 25 Oct 2026
Approved
618 of 817
76% of decided applications; 20 withdrawn, 59 undecided
Typical time to a decision
57 days
median, from 816 decisions with both dates published
Decided within 8 weeks
395 of 816
8 weeks is the usual statutory period; councils can agree extensions
See what was approved near your own address
The The Signal Report shows approvals and refusals for two-storey and first-floor extensions within 250 m, 500 m and 1 km of your home, the council's reasons for refusing similar schemes, your property's planning history and the constraints on the plot. Free preview for any address.
Recent decisions
- Approved4 ST MARTINS ROAD WEST DRAYTON
Erection of part single part double storey side/rear extension, side extension to existing rear extension, and a front porch
34802/APP/2026/2116 · decided 23 Oct 2026
- ApprovedNorthwood
Erection of a double storey rear and side extension, first floor front porch, conversion of roof space to habitable use to include rear dor…
49177/APP/2026/1775 · decided 22 Oct 2026
- ApprovedUxbridge
Conversion of roof space to habitable use to include a rear dormer with Juliette balcony, erection of a two storey extension to the rear, a…
2727/APP/2026/1851 · decided 22 Oct 2026
- Refused17 THE DRIVE ICKENHAM
Erection of Front Porch, ground floor rear extension, part first floor side and rear extension, alteration of roof
27617/APP/2026/2114 · decided 22 Oct 2026
Proposed 2 storey side and part rear extensions.
60628/APP/2026/2109 · decided 21 Oct 2026
Why Hillingdon refuses two-storey and first-floor extensions
The council's own words, quoted from recent decision notices.
“1. The proposed extensions, by reason of their cumulative size, scale, bulk, depth, width, height, proximity to the side boundary, would result in the closing of an important gap characteristic to the area, resulting in a cramped appearance. The proposed development would therefore fail to harmonise with the established built environment resulting in a detrimental impact on the character and appearance of the immediate street scene and the wider surrounding area. The proposal thereby fails to comply with Policy BE1 of the Hillingdon Local Plan: Part One- Strategic Policies (November 2012), Po…”
“1. The proposed ground and first floor front/side extension and hip-to-gable roof conversion, by reason of their overall size, scale, bulk and design, together with the lack of set in from the side boundary and limited setback from the front building line would result in an overly dominant and visually intrusive form of development. The proposal would fail to appear as a subordinate addition to the host dwelling and would be detrimental to its architectural composition and to the character and appearance of the street scene and surrounding area. The development would therefore fail to comply…”
“1. The development by virtue of its depth, width, overall size, bulk and proximity to neighbouring property at 59 Whitethorn Avenue would be detrimental to the residential amenities of the occupiers by reason of loss of light, loss of outlook, overshadowing and overdominance. The proposal would therefore be contrary to Policy BE1 of the Hillingdon Local Plan: Part One - Strategic Policies (2012), Policies DMHB 11 and DMHD 1 of the Hillingdon Local Plan: Part 2 - Development Management Policies (2020) and the National Planning Policy Framework (2026). 2. The proposed extension, by virtue of it…”
Other home extensions in Hillingdon
- Loft conversions
786 of 931 approved (84%)
- Single-storey rear extensions
1,395 of 1,564 approved (89%)
- Single-storey side extensions
213 of 251 approved (85%)
How these figures are made
Planning applications London Borough of Hillingdon received Oct 2021 to Oct 2026, from the council's public planning register as collected by Planning Signal. An application counts as a two-storey extension when its own description says so (rules-based classification, tested against blind labelled samples). Duplicate records of one application are counted once. The approval figure counts approved and refused planning applications only: withdrawn and undecided ones, lawful development certificates and prior approvals are left out. Decision times use the received (or validated) date and the decision date the council published.
Past decisions describe what happened to other applications. They are not a prediction for yours: every application is decided on its own design and the council's current policies.