Isallt-fawr is a Grade II listed building in the Snowdonia National Park local planning authority area, Wales. First listed on 19 January 1952. House.
Isallt-fawr
- WRENN ID
- night-foundation-plum
- Grade
- II
- Local Planning Authority
- Snowdonia National Park
- Constituency
- Dwyfor Meirionnydd MP: Liz Saville Roberts (PC)
- Country
- Wales
- Date first listed
- 19 January 1952
- Type
- House
- Address
- Isallt-fawr, Dolbenmaen, Gwynedd
- OS grid reference
- SH 534 443
- Coordinates
- 52.97659, -4.18477
- Source
- Cadw listing
Description
Isallt-fawr is a 17th century building located on a downhill site, constructed from long local rubble stonework with some boulders at the lower end. It features a slate roof and is one storey with attics, approximately symmetrical in design, consisting of three bays with deep fire bays at each end. The central entrance has a boarded door topped with a radial slate voussoir lintel and a drip ledge. The ground floor has six-paned windows with slate lintels, and a small fire window on the right; the upper floor contains four-paned windows, each set within a small gable. At the rear, there are two simple gabled dormers flanking a late 20th century rear wing. The lower gable end previously had four small windows on either side of the stack, all with projecting drip ledges, though only two of these windows remain. The building is supported by large boulder footings and has stone stacks with drip courses.
While not accessible during the inspection, it is believed that the main living room is located at the uphill end, featuring a winding stair beside a large gable fireplace, with a central hallway and a parlour at the lower end that has a window beside its large fireplace. The roof has been modernized.
Local climate
Isallt-fawr sits in one of the wettest parts of the UK, with an average of 1,550 mm of rain a year. This makes it wetter than 99% of listed buildings in the UK. Its exposure to wind-driven rain is greater than that of 99% of listed buildings.
It experiences an average of 20 freeze-thaw cycles a year, fewer than 79% of listed buildings. Of these, 8 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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- No EPC on record for this property
- No sale records on file
- No related consent applications matched
- 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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