15 Castle Avenue Datchet Slough SL3 9BA Data via plota.co.uk

26/02230/CPD - Cert of Lawfulness of Proposed Dev Awaiting decision
Extensions & alterations

Proposal

Certificate of lawfulness to determine whether the proposed single storey rear extension is lawful. Data via plota.co.uk

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View original council record ↗Last checked

Application progress

✓
Received
9 Sept 2026
Decision
Expected by 3 Nov 2026

Under consideration

No decision has been issued yet. Plota predicts a decision around 1 Nov 2026, from Windsor and Maidenhead's recent extensions.

Documents 3

Application forms 2

PDF Application form redacted Application Forms · 9 Sept 2026 View ↗ PDF Cil form CIL Documents · 9 Sept 2026 View ↗

Other documents 1

PDF History log Property History · 10 Sept 2026 View ↗

All documents on the council site ↗

Site constraints 6

Flood zone 3, rivers and sea
High chance: a 1 in 100 or greater annual chance from rivers, or 1 in 200 from the sea. Any development here needs a flood risk assessment. Defences are not counted.
The Environment Agency flood map for planning. Homes in zone 3 must also pass the sequential test. Surface water flooding is a separate map.
Flood map ↗
National infrastructure project 185 m away: M4 Junctions 3 to 12 Smart Motorway
The site is 185 m from the project boundary. Highway, decided. The project page says whether consent was granted. Also within 2 km: Expansion of Heathrow Airport (Third Runway) (at pre-application, 926 m).
Nationally significant infrastructure projects (power stations, electricity lines, pipelines, major roads and railways, harbours, airports and reservoirs) are consented by a Secretary of State under the Planning Act 2008, after an examination by the Planning Inspectorate, rather than by the council. The boundary is the one the Inspectorate consults on and can change as the scheme does. Projects are shown within 2 km of the site.
Planning Inspectorate project page ↗
Also on the record
Radon affected area, class 2; Inside the Datchet built-up area; Green belt 41 m away: London; Natural England's Provisional ALC map (1:250,000, 1970s) had this area as grade 1, but it predates the buildings here and the current map does not class it as farmland.
Not affected
No listed building at the site · No scheduled monument at the site

Checked on 6 October 2026. Historic England, the Environment Agency, Natural England, the Planning Inspectorate, the British Geological Survey and UK Health Security Agency (radon, contains BGS materials © UKRI) and council datasets, Open Government Licence. A boundary can run through a site and the council holds the definitive record: confirm with the council before relying on this.

Sales history 1

Last sold for £250,000 in August 2002. Detached house, freehold.

28 August 2002£250,000

Sale prices from HM Land Registry's price paid record, matched to this application by its address.

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Other new applications on this street

1 May 2026Approved

6 Castle Avenue Datchet Slough SL3 9BA

Outbuilding ancillary to the main dwelling, with new patio and steps

26/01087/FULL

Nearby new applications

7 Oct 2026Pending

14 Eton Road Datchet Slough SL3 9AY

Part first floor part second floor side extension (part retrospective).

26/02241/FULL
6 Oct 2026Pending

139A Slough Road Datchet Slough SL3 9AE

New boundary treatment

26/02412/FULL
5 Oct 2026Pending

Eton Manor 60 Eton Road Datchet Slough SL3 9AY

Single storey rear extension no greater than 6.00m in depth, 3.00m high with an ...

26/02425/PDXL
5 Oct 2026Pending

14 Eton Road Datchet Slough SL3 9AY

Variation (under Section 73a) of Condition 2 and Condition 11 (Approved Plans) t...

26/02242/VAR
18 Sept 2026Pending

11 Agars Place Datchet Slough SL3 9AH

1no. Lime tree and 2no. Cherry trees - works as per photographs (026/1995/TPO).

26/02264/TPO
7 Sept 2026Withdrawn

10 Gables Close Datchet Slough SL3 9BB

Part single part two storey side/rear extension, alterations to fenestration and...

26/02047/FULL

Important details

Council
Windsor and Maidenhead
Application type
Cert of Lawfulness of Proposed Dev
Postcode
SL3 9BA
Received
9 Sept 2026
Validated
9 Sept 2026
Ward
Datchet Horton And Wraysbury
Parish
Datchet Parish
Target decision
3 Nov 2026
Applicant
Show
Agent
Show

Decision outlook

Day 49 of the 56-day target. Windsor and Maidenhead usually decides extensions by day 53.

Day 497 days to the 56-day target
76%decided within 8 weeks
75%approved
862decided in the last year

Plota live figures for extensions decided by Windsor and Maidenhead in the last twelve months, from validation. Windsor and Maidenhead decision record →

Consultation & key dates

Alt. reference
PP-15200874
Planning Portal ref
PP-15200874
Statutory expiry
3 Nov 2026
Env. assessment
No

Historical activity at this location

26 previous applications on record - archival context, not part of the live application.

This property

Previous applications at this address

2019 Refused
Single storey rear extension with increased 1st floor accommodation above, with rear Juli…
19/01926/FULL
2018 Approved
Single storey rear extension and x1 rear dormer with Juliette Balcony following demolitio…
18/00788/FULL
2017 Approved
Hip to gable extensions to accommodate loft conversion to form habitable accomodation and…
17/00803/FULL
2016 Refused
Certificate of lawfulness to determine whether the construction of hip to gable roof exte…
16/03660/CPD
Within ~100m

Nearby activity

2025 Approved
4 Castle Avenue Datchet Slough SL3 9BA
Part garage conversion, single storey front extension, single storey rear extension, 1no…
25/01954/FULL
2025 Refused
4 Castle Avenue Datchet Slough SL3 9BA
Part garage conversion, single storey front extension, single storey rear extension, 1no…
25/00899/FULL
2023 Refused
4 Castle Avenue Datchet Slough SL3 9BA
Single storey front extension, single storey rear extension, partial garage conversion, 1…
23/02493/FULL
2023 Refused
10 Castle Avenue Datchet Slough SL3 9BA
Single storey rear extension no greater than 6.30m in depth, 3.07m high with an eaves hei…
23/02503/PDXL
2023 Approved
133 Slough Road Datchet Slough SL3 9AE
Two storey front/side extension, side canopy, thermal insulation to the existing walls an…
23/01052/FULL
2023 Refused
10 Castle Avenue Datchet Slough SL3 9BA
Single storey rear extension no greater than 6.7m in depth, 3.6m high with an eaves heigh…
23/00353/PDXL
2022 Approved
10 Castle Avenue Datchet Slough SL3 9BA
Certificate of lawfulness to determine whether the alterations and extension to first flo…
22/01288/CPD
2022 Refused
133 Slough Road Datchet Slough SL3 9AE
Non material amendments to planning permission 21/03671 for amendments to the design of t…
22/02312/NMA
2021 Approved
133 Slough Road Datchet Slough SL3 9AE
Two storey front extension, side canopy, detached garage with accommodation within the ro…
21/03671/FULL
2021 Withdrawn
10 Castle Avenue Datchet Slough SL3 9BA
Single storey side/rear extension, hip to gable with x2 front dormers, x1 rear dormer, x1…
21/01678/FULL
2021 Refused
Land At 16 Castle Avenue Datchet Slough
Outline application for 1no. three bedroom detached dwelling with all matters reserved.
21/00211/OUT
2021 Approved
8 Castle Avenue Datchet Slough SL3 9BA
Certificate of lawfulness to determine whether the proposed side dormer to facilitate add…
21/00867/CPD
2019 Approved
14 Castle Avenue Datchet Slough SL3 9BA
Single storey rear extension incorporating rear dormer and accomodation in roof space.
19/03354/FULL
2019 Approved
14 Castle Avenue Datchet Slough SL3 9BA
Single storey rear extension no greater than 2.7m in depth, 4m high with an eaves height…
19/02759/PDXL
2019 Refused
14 Castle Avenue Datchet Slough SL3 9BA
Single storey rear extension no greater than 6.032m depth, 4m high and an eaves height of…
19/02091/PDXL
2019 Refused
14 Castle Avenue Datchet Slough SL3 9BA
Single storey rear extension no greater than 6.032m in depth, 4m high with an eaves heigh…
19/01583/PDXL
2018 Approved
21 Castle Avenue Datchet Slough SL3 9BA
Raising of eaves and main ridge to enlarge first floor accommodation including front and…
18/03051/FULL
2018 Approved
21 Castle Avenue Datchet Slough SL3 9BA
Certificate of lawfulness to determine whether the proposed single storey side extension…
18/01778/CPD
2018 Approved
21 Castle Avenue Datchet Slough SL3 9BA
New detached double garage following demolition of the existing garage.
18/01695/FULL
2018 Approved
21 Castle Avenue Datchet Slough SL3 9BA
Construction of a two storey rear extension and raising of the roof including x3 front do…
18/00265/FULL
2016 Approved
17 Castle Avenue Datchet Slough SL3 9BA
Single storey rear extension no greater than 4.3m depth, 3.9m high and an eaves height of…
16/03100/PDXL
2016 Withdrawn
17 Castle Avenue Datchet Slough SL3 9BA
Single storey rear extension no greater than 4.30m depth, 3.90m high and an eaves height…
16/02821/PDXL
Windsor and Maidenhead
Planning Authority Score
5.3/10
Average
#135 of 296 councils
Relevant to this application:
Householder decisions

Windsor and Maidenhead is faster than most councils at deciding householder applications, ranking #82 out of 296. Only 28% of applications have the time limit extended, well below the 41% national average - the council usually decides on time. Windsor and Maidenhead is also one of the strictest councils - it refuses more householder applications than almost any other, with only 74% approved vs 90% nationally.

One of the strictest councils
only 74% approved vs 90% nationally
These figures are council-wide context, not a prediction for this application. View full council performance
Windsor and Maidenhead decision statistics
Based on MHCLG data, the year to March 2026
72%
Overall approval rate
Below avg (87%) #293 of 296
74%
Householder approved
Below avg (90%) #294 of 296
75%
Decided in 8 weeks
Above avg (63%) #82 of 296
28%
Extended time limit
Below avg (41%) #47 of 296
44%
Minor dwellings approved
156 decided (1-9 homes)
96%
Major dwellings approved
27 decided (10+ homes)
64%
Change of use approved
25 decided
1,530
Total decisions
434 refused in the year to March 2026
Source: MHCLG planning statistics · See full council rankings

Sale prices: Contains HM Land Registry data © Crown copyright and database right 2026. This data is licensed under the Open Government Licence v3.0.

Freehold boundary: © Crown copyright and database rights 2026, HM Land Registry. Polygons © Crown copyright and database rights 2026 Ordnance Survey 100026316. Conditions of use