Britannia Bridge is a Grade II listed building in the Gwynedd local planning authority area, Wales. First listed on 26 September 2005. Bridge.
Britannia Bridge
- WRENN ID
- plain-mantel-heath
- Grade
- II
- Local Planning Authority
- Gwynedd
- Constituency
- Dwyfor Meirionnydd MP: Liz Saville Roberts (PC)
- Country
- Wales
- Date first listed
- 26 September 2005
- Type
- Bridge
- Address
- Britannia Bridge, Porthmadog
- OS grid reference
- SH 570 384
- Coordinates
- 52.92473, -4.12748
- Source
- Cadw listing
Description
The Britannia Bridge is a double-carriageway bridge built with large blocks of squared local stone arranged in regular courses. The original construction is most visible on the north side, featuring segmental arches made of freestone voussoirs with recessed keystones. The bridge has prominent rounded cutwaters that include slots for tidal gates, and above these are shallow buttresses that rise to a raised band at the base of the parapet. The parapet over the river, which dates from the 20th century, is made of coursed slate-stone. The original parapet, which is lower and curves out to round terminal piers, has survived above the abutments; on the east side, it abuts Bridge Cottage. On the south side, facing the harbour, the bridge has been extended by widening the deck to create a footway supported by the cutwaters, which also retain slots for tidal gates. The 20th-century parapet on this side is similar to that on the north side.
Local climate
Britannia Bridge 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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- 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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