Site of c. 1.39 ha, Thornhill House, Cherry Garth, Mount Merrion, Blackrock, Co.Dublin A Protected Structure (RPS No. 936)
Conservation of Thornhill House and construction of ten new homes in Blackrock.
D21A/0161 · Dun Laoghaire Rathdown County Council · Lodged 26 February 2021
- Reference
- D21A/0161
- Authority
- Dun Laoghaire Rathdown County Council
- Register status
- Decided
- Type
- Permission
- Received
- 26 February 2021
Summary
AI-generatedThe development consists of conservation works to Thornhill House, a protected structure, to upgrade it as a single family residence. It also includes the provision of five own-door dwellings through the conversion of outbuildings, and five new mews dwellings.
- Residential units
- 11
- Storeys
- 2
- Floor area
- 494 m²
Generated from the description above by an AI model and may contain mistakes. The council’s description is the authoritative record.
Official record
Development description
Permission for development. The proposed development will consist of: conservation works to thornhill house, to upgrade the house as a single family residence 494 sqm; the provision of 5no. Own door two storey 2 bed dwellings to the rear of thornhill house through the renovation, conversion and extension of an existing return and outbuildings located around an existing rear stable yard; and the provision of a terrace of 5 no. One-and-a-half storey mews dwellings located to the south of thornh...
Land-use zoning
What this land is zoned for
“A To provide residential development and improve residential amenity while protecting the existing residential amenities”
Objective set by the COUNTY DEVELOPMENT PLAN 2022-2028 (2022–2028). The planning authority decides each application on its own merits — this is the zoning context, not a compliance assessment.
Read the zoning objectives in the development planBuilt & sold
What happened next
Beyond the decision: whether this development was built, and what property here has sold for.
Built — construction complete
A commencement notice records works starting on 7 August 2023. A completion certificate was lodged on 22 July 2025.
Notified floor area: 157 m²
12 commencement notices are linked to this development.
Recent sales nearby
within 500 m| Address | Date | Price | Distance |
|---|---|---|---|
| 61 The Stables, Thornhill Oaks, Mount Merrionprice excludes VAT | Aug 2025 | €889,868 | 27 m |
| 50 Thornhill Oaks, Cherry Garth, Mount Merrion | Sept 2025 | €1,500,000 | 47 m |
| Thornhill, Cherry Garth, Mount Merrion | Aug 2025 | €1,750,000 | 49 m |
| 49 Thornhill Oaks, Cherry Garth, Mount Merrion | Dec 2025 | €1,430,135 | 50 m |
| 63 Thornhill Oaks, Blackrock, Co. Dublin | May 2026 | €870,000 | 51 m |
| Apt.28 - Thornhill Oaks, Cherry Garth - Mount Merrion, Blackrock | Jul 2025 | €999,999 | 53 m |
| 49 Thornhill Oaks, Cherry Garth, Mount Merrionprice excludes VAT | Jan 2025 | €1,145,374 | 58 m |
| 62 Thornhill Oaks, Blackrock, Co. Dublinprice excludes VAT | Mar 2026 | €859,031 | 62 m |
Nearby properties, not this site — a guide to local values.
Sources: Building Control Management System (commencement notices) and the Residential Property Price Register, licensed under CC BY 4.0. Records are matched to this application by location and may not be exhaustive; always confirm against the official source before relying on them.
Key dates
Timeline
- Application received26 February 2021
- Decision issued22 April 2021
- Appeal submitted18 May 2021
- Appeal decided11 August 2022
In the area
Applications near this site
Other planning applications within about 500 m — what else is being proposed or built nearby.
- RefusedAt this site
Permission for development. The proposed development will consist of the reconfiguration and redesign of the…
Site of c. 1.39 ha, Thornhill House, CherryGarth, Mount Merrion, Blackrock, Co. Dublin
D20A/0432Dún Laoghaire–RathdownLodged 22 Jun 2020Housing estate
- InvalidAt this site
Permission for development. The proposed development will consist of the reconfiguration and redesign of the…
Site of c. 1.39 ha, Thornhill House, CherryGarth, Mount Merrion, Blackrock, Co. Dublin
D20A/0274Dún Laoghaire–RathdownLodged 30 Mar 2020Housing estate
- RefusedAt this site
Permission for development. The proposed development will consist of the temporary removal of the eastern…
At a site of c.1.39ha, Thornhill House, Cherry Garth, Mount Merrion, Blackrock, Co. Dublin (Protected Structure Ref. No. 936)
D20A/0057Dún Laoghaire–RathdownLodged 28 Jan 2020Alterations
- GrantedAt this site
Apply for Retention Permission for development within the grounds of Thornhill Oaks, and Thornhill House, a…
Thornhill Oaks, Cherrygarth, Mount Merrion, Blackrock, Co. Dublin, and Thornhill House (a Protected Structure) A94W7C5
D25A/0862/WEBDún Laoghaire–RathdownLodged 12 Nov 2025Retention
- GrantedAt this site
Oak View Property Developments Limited, intend to apply for Retention Permission for development within the…
Thornhill Oaks, Cherrygarth, Mount Merrion, Blackrock, Dublin, A94W7C5
D24B/0425/WEBDún Laoghaire–RathdownLodged 8 Oct 2024Retention
- Compliance submissionAt this site
Compliance with Condition no. 11 of Reg Ref no. ABP-31028521 (D21A/0161)
Site of c. 1.39 ha, Thornhill House, Cherry Garth, Mount Merrion, Blackrock, Co.Dublin A Protected Structure (RPS No. 936)
D21A/0161/C10Dún Laoghaire–RathdownLodged 28 Jun 2023Other
- Compliance submissionAt this site
Compliance with Condition no. 19 of Reg Ref no. ABP-31028521 (D21A/0161)
Site of c. 1.39 ha, Thornhill House, Cherry Garth, Mount Merrion, Blackrock, Co.Dublin A Protected Structure (RPS No. 936)
D21A/0161/C14Dún Laoghaire–RathdownLodged 1 Feb 2024Other
- Compliance submissionAt this site
Compliance with Condition no.4 of Reg Ref no. ABP-31028521 (D21A/0161)
Site of c. 1.39 ha, Thornhill House, Cherry Garth, Mount Merrion, Blackrock, Co.Dublin A Protected Structure (RPS No. 936)
D21A/0161/C2Dún Laoghaire–RathdownLodged 4 Apr 2023Other
Related developments
Similar applications
Ranked by what these developments actually propose, not by matching words — so you can see how comparable applications were decided.
- InvalidNew dwelling
Redesign of the permitted No. 40 Thornhill Oaks (D20A/0432 ABP 308150-20) to now provide a part single/part 2…
Site at 40 Thornhill Oaks, Mount Merrion, Blackrock, Co Dublin
D23A/0782Dún Laoghaire–RathdownLodged 11 Dec 2023
- RefusedAlterations
Redesign of the permitted no. 40 Thornhill Oaks (D20A/0432, ABP308150-20) to provide a part single/part two…
Site at Thornhill Oaks, Mount Merrion, Blackrock, Co Dublin
D24A/0059Dún Laoghaire–RathdownLodged 31 Jan 2024
- GrantedRetention
Apply for Retention Permission for development within the grounds of Thornhill Oaks, and Thornhill House, a…
Thornhill Oaks, Cherrygarth, Mount Merrion, Blackrock, Co. Dublin, and Thornhill House (a Protected Structure) A94W7C5
D25A/0862/WEBDún Laoghaire–RathdownLodged 12 Nov 2025
- WithdrawnNew dwelling
Development will consist of the redesign of the permitted gatelodge house (D20A/0432, ABP-308150-20) to now…
Site at Thornhill Oaks, Mount Merrion, Blackrock, Co Dublin
D23A/0013Dún Laoghaire–RathdownLodged 9 Jan 2023
- GrantedExtension
Permission for development. The development will consist of the conservation and refurbishment of the…
8, Mulgrave Terrace, Dun Laoghaire, Co Dublin, (A protected structure)
D20A/0749Dún Laoghaire–RathdownLodged 15 Oct 2020
- GrantedExtension
Permission for development. The development will consist of: removal of non-original single storey extension…
Altona, 66 George's Avenue, Blackrock, Co. Dublin, A94 A0W9, a protected structure A94 A0W9
D21A/0336Dún Laoghaire–RathdownLodged 20 Apr 2021
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