Nant Dyar Railway Viaduct is a Grade II listed building in the Brecon Beacons National Park local planning authority area, Wales. First listed on 27 July 2000. Viaduct.

Nant Dyar Railway Viaduct

WRENN ID
plain-thatch-evening
Grade
II
Local Planning Authority
Brecon Beacons National Park
Constituency
Monmouthshire MP: Catherine Fookes (Lab)
Country
Wales
Date first listed
27 July 2000
Type
Viaduct
Address
Nant Dyar Railway Viaduct, Clydach, Llanelly, Monmouthshire
OS grid reference
SO 232 127
Coordinates
51.80818, -3.11484
Source
Cadw listing

Also on this page: flood risk · radon risk · weather exposure · detailed attributes ↓

Description

The Nant Dyar Railway Viaduct is an eight-arch structure that spans a steep gorge of the Nant Dyar. The viaduct gently curves, measuring 312 feet (95 metres) in length and standing 75 feet (23 metres) high. It is built of rock-faced limestone, featuring blue Staffordshire brick arch rings made up of four header courses, with each arch being 30 feet (9 metres) wide. A low parapet sits above a rock-faced stringcourse.

Local climate

Nant Dyar Railway Viaduct sits in a wetter-than-average part of the UK, with an average of 1,040 mm of rain a year. This makes it wetter than 83% of listed buildings in the UK. Its exposure to wind-driven rain is greater than that of 75% of listed buildings.

It experiences an average of 48 freeze-thaw cycles a year, more than 89% of listed buildings. Of these, 24 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

Sign in or create a free account to unlock:

  • 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
Create free account

Matched applications, energy data and sale records are assembled automatically and may contain errors. Flag incorrect data.

Similar buildings

The closest matches to this building from all 493,000 UK listed buildings, by architecture, period and materials.

See all similar buildings →

this building   1 similar   nearby listed buildings

Nearby listed buildings

  1. Limekilns at Clydach Limeworks Grade II 45 m
  2. Smart’s Bridge Grade II* 628 m
  3. Pantglas Bridge Grade II 647 m
  4. Oak House Grade II 699 m
  5. Tramroad Bridge over Sychnant River Grade II 718 m
  6. Three Arch Viaduct of former Merthyr, Tredegar and Abergavenny Railway Grade II 723 m
  7. Clydach Wesleyan Chapel including Sunday School and railed forecourt Grade II 751 m
  8. Tramroad Bridge near junction of A465 and Station Road Grade II 980 m
  9. Railroad Bridge at Maesygwartha Grade II 1.0 km
  10. Limekilns at Llanelly Limeworks Grade II 1.1 km