Knocklyon

More than 2,000 parcels touch this townland. The map cannot draw that many.

• R2RES (Existing residential)
  South Dublin County Development Plan 2022-2028, South Dublin The zoning objective in the plan
• G1OS (Open space, park)
  South Dublin County Development Plan 2022-2028, South Dublin The zoning objective in the plan
• G3HA-DV (Conservation, amenity or buffer space, corridor/belt, landscape)
  South Dublin County Development Plan 2022-2028, South Dublin The zoning objective in the plan
• M3DC (District, neighbourhood centre)
  South Dublin County Development Plan 2022-2028, South Dublin The zoning objective in the plan
• M3LC (District, neighbourhood centre)
  South Dublin County Development Plan 2022-2028, South Dublin The zoning objective in the plan

Source: Tailte Éireann and the Department of Housing (MyPlan), national zoning, CC BY 4.0.

• 9 Sept 2026Recommended decision

  Rear extension c22m, front door to be brought forward to existing porch door. Building up right-hand side (if facing) of garage in similar brick finish to existing house to narrow the garage door opening.

  Declaration of exemption sect. 5 · South Dublin County Council, ED26/0098

• 13 Aug 2026Declared exempt

  Replacing one car park space with one bike rack for bicycles to be parked for visitors to the Iona Centre. Improving accessibility and encouraging cyclists to come to the centre.

  Declaration of exemption sect. 5 · South Dublin County Council, ED26/0081

• 13 Aug 202645 day assessment

  Conversion of existing attic space comprising of modification of existing roof structure; raising of existing gable c/w window; new access stairs; two roof windows to the front and flat roof dormer to the rear.

  Permission · South Dublin County Council, SD26B/0371W

• 12 Jun 2026Request additional information

  Repair of part of storm damaged boundary wall and fence.

  Declaration of exemption sect. 5 · South Dublin County Council, ED26/0057

• 9 Apr 2026Grant permission

  Proposed build-up of existing hip in roof to side of roof into Dutch hip at attic level, with window in proposed gable wall, dormer roof window on rear slope of roof all at attic level.

  Permission · South Dublin County Council, SD26B/0165W

• 8 Apr 2026Refuse ext. of duration of permission

  Construction of a two storey extension at the side and a single storey extension to the rear of existing semi-detached house; canopy at the front of the house above the main entrance and continuing over a new single storey bay window; 3 no. west facing roof lights to the rear of the house; 3 no. new west-facing roof-lights to the single storey extension to the rear of the house; 3 no. windows to the new end wall and gable; connection into existing public mains; internal reconfiguration; all with a total floor area of approx.. 49sq.m and associated site works.

  Extension of duration of permission · South Dublin County Council, SD21B/0201/EP

• 3 Apr 2026Grant permission

  Amendmetns to the first floor extension previously granted planning permission Reg Ref: SD21B/0021

  Permission · South Dublin County Council, SD26B/0156W

• 23 Jan 2026Grant permission

  Conversion of existing attic space comprising of modification of existing roof structure, raising of existing gable c/w window, new access stairs, 2no. roof windows to the front and flat roof dormer to the rear.

  Permission · South Dublin County Council, SD26B/0027W

• 24 Nov 2025Grant permission

  Construction of a single-storey flat-roof front extension.

  Permission · South Dublin County Council, SD25B/0658W

• 21 Nov 2025Grant permission

  The development will consist of amendments to previously approved planning permission reg. Ref. SD25B/0436W comprising of modifications to the existing hipped roof structure including raising of existing gable wall to form gable roof, demolition of existing chimney to facilitate raising of gable wall, provision of 1no. additional rooflight to front of dwelling.

  Permission · South Dublin County Council, SD25B/0655W

• 6 Nov 2025Grant permission

  Variation to the previously granted planning permission Pl. Ref SD22A/0287. The development consists of a two storey detached house. Variations to internal layouts, elevations, vehicular access, and all associated site works below and above ground.

  Permission · South Dublin County Council, SD25A/0200W

• 21 Aug 2025Grant permission

  Planning permission for (1) Demolition of single storey front porch and garage extension (2) For a new first floor extension over existing side garage and a new single storey porch and garage extension to the front (3) 2 new velux windows in main roof to front (4) All associated ancillary site works

  Permission · South Dublin County Council, SD25B/0505

• 31 Jul 2025Grant permission

  The development consists of converting a carport, construction of a single-storey front extension, and all ancillary works necessary to facilitate the development.

  Permission · South Dublin County Council, SD25B/0474W

• 25 Jul 2025Grant permission

  To remove the existing to store to side of the existing two storey semi-detached dwelling and replace with a new single storey extension to the front and side with a tiled roof to match existing with a ventilated rooflight: internal alterations & associate site works

  Permission · South Dublin County Council, SD25B/0468

• 9 Jul 2025Grant permission

  The construction of a new attic level conversion and dormer extension to include alterations to rear elevation of existing dwelling, with internal alterations to facilitate the proposed attic conversion, and the provision of 1no. new rooflight to front of existing dwelling.

  Permission · South Dublin County Council, SD25B/0436W

• 7 Jul 2025Grant permission

  alterations to previously approved planning application Reg Ref No. SD24A/0034. The proposed alterations affect House B (5A Knocklyon Ave) of the previous application to include a 1st floor extension to the side (circa 6 Sq/M) & a single storey extension to the rear (circa 3 Sq/M) & all associated works

  Permission · South Dublin County Council, SD25B/0433W

• 17 Jun 2025Grant permission

  Conversion of existing attic space comprising of modification of existing roof structure, raising of existing gable c/w window, new access stairs, 2no. roof windows to the front and flat roof dormer to the rear.

  Permission · South Dublin County Council, SD25B/0399W

• 29 May 2025Invalid - site notice

  (i) construction of a new attic level conversion and dormer extension to include alterations to rear elevation of existing dwelling, (ii) internal alterations to facilitate the proposed attic conversion, and (iii) provision of 1no. new rooflight to front of existing dwelling.

  Permission · South Dublin County Council, SD25B/0304W

• 5 May 2025Grant permission for retention

  Planning Permission for Retention for the construction of a 2.5m high side boundary wall / timber fence facing onto no 37 Coolamber Park, and the construction of a 2.9m high rear boundary timber fence facing onto the side elevation of 36 Idrone Close, Dublin 16, D16 A2R7

  Retention · South Dublin County Council, SD25B/0253W

• 1 Apr 2025Declared exempt

  Removal of exisitng timber shed to be replaced by new flat roof garden room / store to the rear of the property.

  Declaration of exemption sect. 5 · South Dublin County Council, ED25/0031

• 12 Mar 2025Grant permission

  Dormer to rear of existing converted attic space, single storey extensions to rear and side of existing dwelling and all associated site works

  Permission · South Dublin County Council, SD25B/0133W

• 10 Mar 2025Invalid - site notice

  Conversion of existing attic space to non-habitable storage/office area with new revised roof profile (from hipped roof to gable end roof) to side/rear, 2 rooflights to front elevation, Dormer to rear, ground floor extension to rear, new porch area to front with internal modification and associated site works.

  Permission · South Dublin County Council, SD25B/0114W

• 7 Mar 2025Grant permission

  Detached Two storey Three bedroom house with shared entrance to side.

  Permission, 1 home · South Dublin County Council, SD25A/0050

• 24 Feb 2025Invalid - site notice

  Conversion of existing attic space to non-habitable storage/office area with new revised roof profile (from hipped roof to gable end roof) to side/rear, 2 rooflights to front elevation, Dormer to rear, ground floor extension to rear, new porch area to front with internal modification and associated site works.

  Permission · South Dublin County Council, SD25B/0084W

• 6 Feb 2025Grant permission

  Single storey front extension.

  Permission · South Dublin County Council, SD25B/0045W

The 25 most recent of over 100 applications.

Source: National Planning Applications, Department of Housing, Local Government and Heritage, CC BY 4.0. Applicants are not shown.

Designated sites

No designated site (Special Area of Conservation, Special Protection Area, Natural Heritage Area or proposed one) touches the townland of Knocklyon.

Recorded monuments

• DU022-019 Castle - tower house
  Description

  Located at the foot of the Dublin Mountains off a by road that leads to Castlefield Manor housing estate. Knocklyon Castle was associated with Walter de Ridelesford in the medieval period. In the 16th century the castle was said to be ruinous but was, nevertheless, occupied in the 17th century by Piers Archbold, son of Richard Archbold of Kilmacud (Ball 1905, III, 29). It was subsequently converted into a dwelling house. The tower house rises to three storeys with a slated, hipped roof. The exterior has been pebble-dashed. It has a rectangular ground plan (int. dims. L 8.7m; Wth 5.6m) with angle towers in NE and SW angles that have plain slit opes. There is a spiral stairs in the SW tower. A fireplace has been inserted into the E wall at this level. Two-light windows have been inserted into the main floors. The towerhouse can also be entered through a modern opening in the SW tower. A cone-shaped roof has recently been added to the later (Handcock 1899, 95-6; Healy 1975, 1-19). Compilde by Geraldine Stout Date of upload: 25th April 2012

• DU022-111 Fulacht fia
  Description

  Monitoring of topsoil removal in 1998 revealed, a spread of burnt material containing black silt, burnt stone and charcoal fragments. A rectilinear pit 1.1m wide and 0.48m deep had been cut by a subcircular pit 2m long, 1.4m wide and 0.6m deep. Beside this were the remains of a hearth and two linear concentrations of stake-holes-94 in total. The linear arrangement of stake-holes ran on either side of the rectilinear pit, and a number were clearly angled to form a tent-like structure over the pit (Gracie 2000, 35, ).

Architectural heritage

• Knocklyon Cross, monument, 1865–1870 · Regional interest
  Description

  Monolithic square-section rough dressed granite cross, erected in 1867, approximately 2.5 metres high, thirty centimetres in section. Equal-armed cross head, worn incised date to south face. Irregularly shaped granite sub-circular base.

• Prospect House, demesne walls/gates/railings, 1790–1800 · Regional interest
  Description

  Remains of former Georgian estate, c.1795, comprising entrance gate with carved name plaques to gate posts, some walls and outbuildings. Outbuilding converted to private dwelling. Main house demolished, c.1987.

• House, 1800–1840 · Regional interest
  Description

  Terraced two-bay two-storey house on corner site, c.1820. uPVC casement windows in roughcast walls with parapet wall to eaves and cornice to street. Glazed timber door forming main entrance to rear. Pitched slate roof with rendered chimney stacks. Single-storey modern extension to east.

• House, 1800–1840 · Regional interest
  Description

  Terraced three-bay two-storey house, c.1820. Former main four-bay façade to east with lower single-bay infill extension, timber sash windows and projecting single-storey modern extension. Present main façade to west with roughcast walls. Rendered chimney stacks and pitched slate roof. Roughcast rendered boundary wall, sheet metal gates.

• House, 1800–1840 · Regional interest
  Description

  End-of-terrace three-bay two-storey house, c.1820. Rere four-bay façade now main entrance facade. Metal framed leaded casement windows to east. Glazed timber door, timber leaded casement windows to west. Roughcast rendered walls, pitched slate roof.

• Knocklyon Castle, castle/fortified house, 1820–1850 · Regional interest
  Description

  Detached country house c. 1840 incorporating three-storey tower house, c.1435, with two diagonally set corner towers. Rebuilt, c.1620. Roughcast rendered walls with brick eaves course. Square-headed window openings with paired sash windows, elaborate doorcase with timber door, all below drip mouldings, c.1840. Hipped slate roof with large rere chimney. Two-bay two-storey wing to south, c.1780, with timber sash windows and pitched slate roof. Flat-roofed extension to rere. Farm buildings adjacent.

• Knocklyon House, country house, 1830–1860 · Regional interest
  Description

  Detached four-bay two-storey over basement former country house, c.1845. Smooth rendered walls with parallel render quoins. Rusticated ashlar limestone basement. Timber sash windows with architrave surrounds. Pediments and balustraded balconettes to ground floor windows. Timber panelled door set back within flat-roofed, open-fronted porch with elaborately carved limestone frieze, inner walls and opening surrounds. Stained glass windows to side walls. Approached by flight of steps with similarly carved stone balustrades. Hipped slate roof with rendered chimney stacks. Large wing to side, with further ancillary buildings around formal garden.

• Idrone, country house, 1770–1820 · Regional interest
  Description

  Detached five-bay two-storey former country house, c.1790. Full height bow to south end. Roughcast rendered walls. Timber sash windows. Replacement glazed timber door with timber surround and sidelights, all under radial depressed-arched fanlight. Channelled render surround. Hipped slate roof behind parapet. Rendered chimney stacks. Extensions and outbuildings to rere.

• Charleville House, country house, 1820–1860 · Regional interest
  Description

  Detached five-bay two-storey former house, c.1840, now in use as school. Smooth rendered walls with raised quoins and continuous first floor sill course. Timber sash windows with architrave surrounds. Timber panelled door with overlight in off-set two-storey porch with quoins. Hipped slate roof with projecting eaves and three chimney stacks. Wing to west with three-centred arch. Curved screen walls of snecked rock-faced granite with monolithic granite piers to entrance.

Designated sites: National Parks and Wildlife Service. Recorded monuments: Sites and Monuments Record, National Monuments Service. Buildings: National Inventory of Architectural Heritage. Department of Housing, Local Government and Heritage, CC BY 4.0. Works at or in relation to a recorded monument need two months' written notice to the National Monuments Service (National Monuments (Amendment) Act 1994, section 12).

Radon

At the centre of the townland of Knocklyon, about 1 in 20 homes in this area is likely to have high radon levels. Testing a home

Landslides

The 1:50,000 map rates the landslide susceptibility here as moderately low, low, partly inferred.

Terrain model

LiDAR of the Office of Public Works, flown in 2011, at 2 m: tile OPW_3153 (ZIP).

Flooding

The Office of Public Works publishes its flood maps on floodinfo.ie.

Radon Risk Map of Ireland, Environmental Protection Agency, and Landslide Susceptibility Classification, Geological Survey Ireland, both under CC BY 4.0. LiDAR: contains Irish Public Sector Data (Geological Survey Ireland & the Office of Public Works) licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence.

• Knocklyon, Dublin 165 sales

Name

Knocklyon · Cnoc Lín

Area

1,753,179 m² (175.32 ha, 433.22 acres)

Civil parish

Tallaght, and its townlands

Barony

Uppercross

Electoral division

Firhouse-Knocklyon, the unit of the census

Census 2022

3,510 people lived in 1,288 households in the Firhouse-Knocklyon electoral division. 95% of households owned their home. 6% of homes were built since 2001. 3% of dwellings stood vacant on census night, and 0% were holiday homes.

Neighbouring townlands

Ballycragh, Ballycullen, Ballyroan, Butterfield, Oldcourt, Scholarstown, Templeogue, Tymon South

Placenames

Knocklyon on logainm.ie, the Placenames Database of Ireland

Townlands, civil parishes, baronies and electoral divisions, National Statutory Boundaries, Tailte Éireann, CC BY 4.0. Census 2022, Small Area Population Statistics by electoral division, Central Statistics Office, CC BY 4.0. A townland is the smallest land division of Ireland, and the unit of a rural address. Old registers such as the 1901 and 1911 censuses file it under its civil parish and barony.