Plas Gwyn is a Grade II listed building in the Gwynedd local planning authority area, Wales. First listed on 29 May 1968. House. 4 related planning applications.

Plas Gwyn

WRENN ID
grim-grate-jet
Grade
II
Local Planning Authority
Gwynedd
Constituency
Dwyfor Meirionnydd MP: Liz Saville Roberts (PC)
Country
Wales
Date first listed
29 May 1968
Type
House
Address
Plas Gwyn, Llanrug, Caernarfon, LL55 2AQ
OS grid reference
SH 521 631
Coordinates
53.14472, -4.21159
Source
Cadw listing

Also on this page: sale history · EPC · related consents · flood risk · radon risk · weather exposure · detailed attributes ↓

Description

Plas Gwyn is a house dating from the 18th century, with a 3-window front and a gable-lit attic. It has single-storey and 2-storey extensions to the rear, one connecting with a single-storey outbuilding, and another single-storey gabled range attached to the left gable end of the main house. The main house is built of rendered rubble stone, with slate hanging to the right gable end. It has slate roofs, slate coping, and end stacks that are built into the structure. The windows are mostly 12-pane sashes with louvred shutters on the first floor. The ground floor has original tripartite sashes set within shallow segmental-headed recesses. A central 6-panel door, also within a similar recess, has a rectangular overlight and side lights with decorative glazing bars. The ground floor is sheltered by a slate slab-roofed verandah, which projects to the corners and is supported by 4 pairs of cast-iron columns, closely spaced in the centre and more widely spaced at the ends. There is a 16-pane sash window on the ground floor of the left gable end, and a brick roundel in the end wall of the single-storey gabled range. The outbuilding features a substantial ridge stack with a tall brick shaft.

The interior of the house remains relatively unaltered. A dogleg staircase with a cut string, a plain circular newel post, stick balusters, and a moulded handrail rises from the central hall to the attic. One room on the ground floor has an elliptical arch with two half-columns towards the back of the room, and a recessed cupboard to the end wall. The name "Jane Williams/Ty Gwyn" is scratched into the original glass of a front window. While the fireplaces are 20th century additions, original panelled window shutters and plain ceiling cornices are present, along with 6-panel doors throughout the ground and first floors. The attic has boarded doors.

Local climate

Plas Gwyn sits in one of the wettest parts of the UK, with an average of 1,380 mm of rain a year. This makes it wetter than 97% of listed buildings in the UK. Its exposure to wind-driven rain is greater than that of 98% of listed buildings.

It experiences an average of 25 freeze-thaw cycles a year, fewer than 73% of listed buildings. Of these, 12 follow at least 1 mm of rain in the preceding 48 hours. Average temperatures at this location have risen by 0.3°C per decade since 1991.

Averages for 1991–2020; temperature trend 1991–2025. Figures describe the wider area (a grid cell of roughly 10 km), not the individual site. Contains modified Copernicus Climate Change Service information 2026.

More on this building

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  • Full EPC report — heating system, energy costs, size, glazing, construction etc.
  • Sale history — 2 transactions since 1997
  • Related listed building consents — 4 applications
  • Detailed attributes — period, style, materials, features
  • Flood risk assessment
  • Radon risk assessment
  • Weather exposure and heating demand — rain and frost month by month and year by year, wind direction, solar and humidity
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