Grisiau Mawr (steps between Pencei (Cornhill) and Ffordd Garth) is a Grade II listed building in the Gwynedd local planning authority area, Wales. First listed on 30 March 1951. Steps. 2 related planning applications.

Grisiau Mawr (steps between Pencei (Cornhill) and Ffordd Garth)

WRENN ID
over-tin-grain
Grade
II
Local Planning Authority
Gwynedd
Constituency
Dwyfor Meirionnydd MP: Liz Saville Roberts (PC)
Country
Wales
Date first listed
30 March 1951
Type
Steps
Address
Grisiau Mawr (steps between Pencei (Cornhill) and Ffordd Garth), Porthmadog, LL49 9BH
OS grid reference
SH 568 383
Coordinates
52.92339, -4.13094
Source
Cadw listing

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

Description

Grisiau Mawr consists of three steep flights of steps connecting Pencei (Cornhill) to Ffordd Garth. The steps are built between garden walls and the end walls of adjacent buildings. Originally constructed with slate treads, these have been renewed in concrete. An iron handrail is present only at the base of the steps.

Local climate

Grisiau Mawr (steps between Pencei (Cornhill) and Ffordd Garth) sits in one of the wettest parts of the UK, with an average of 1,490 mm of rain a year. This makes it wetter than 98% of listed buildings in the UK. Its exposure to wind-driven rain is greater than that of 97% of listed buildings.

It experiences an average of 32 freeze-thaw cycles a year, fewer than 60% of listed buildings. Of these, 15 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 2005
  • Related listed building consents — 2 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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Nearby listed buildings

  1. Ty Toronto Grade II 15 m
  2. 7 Pencei (Cornhill) Grade II 20 m
  3. 8 Pencei (Cornhill) Grade II 22 m
  4. 9 Pencei (Cornhill) Grade II 25 m
  5. Caffi y Morwr Madog (The Mariner Café) and house Grade II 28 m
  6. Harbourside Clinic and apartments Grade II 30 m
  7. 11 Pencei (Cornhill) Grade II 32 m
  8. 3 Pencei (Cornhill) Grade II 36 m
  9. 12 Pencei (Cornhill) Grade II 36 m
  10. Cornhill Wharf Grade II 37 m