The refurbishment of Flat Holm Island’s Foghorn Station demonstrates the unmatched advantages of specifying the Polyroof Protec System in extreme coastal and heritage-sensitive environments. Its cold-applied, fully bonded membrane enabled precise waterproofing of complex architectural features—including the iconic foghorn drum, trumpet plinth, and parapets—without mechanical fixings or hot works, preserving the building’s Grade II listed fabric. RapidCure technology allowed installation during brief weather windows, while the lightweight resin packs simplified transportation and handling on the remote island. The system’s seamless, durable, and weather-resistant finish delivers long-term protection against high winds, driving rain, salt spray, and wildlife exposure, ensuring the continued functionality and heritage preservation of one of Wales’s most significant maritime structures.
The Challenge
The refurbishment of the Foghorn Station on Flat Holm Island combined intense environmental constraints with significant heritage responsibilities. Originally constructed in 1906 by Trinity House to accompany the island’s 18th-century lighthouse, the building housed one of the region’s most powerful compressed-air fog signals. Its siren, once powered by an 11 kW (15 hp) engine, was capable of sounding blasts at two-minute intervals that could be heard from both sides of the Bristol Channel. The structure remains a vital part of Wales’s maritime safety network and a rare example of early 20th-century foghorn architecture. As a Grade II listed building, it required a refurbishment that protected its historical integrity while ensuring continued operational reliability.
Located six miles offshore, the site is exposed to constant high winds, salt spray, and driving rain, with access limited to pre-arranged boat transfers. All materials, tools, and personnel needed to be transported by sea and then manually hauled up steep, uneven terrain—creating major logistical barriers and requiring a system with lightweight, easy-to-handle components.
The roof had deteriorated significantly after decades of exposure. Surveys revealed a complex and unstable build-up: a concrete deck overlaid with an aged bituminous system and a defective 18 mm GRP membrane. Due to the poor condition of these layers, a full strip-back and remedial preparation was essential. At the same time, the works needed to protect numerous historic features, including the iconic foghorn drum, trumpet plinth, and original parapet walls. Conventional felt or single-ply membranes were unsuitable, as they would require mechanical fixings, visible laps, or hot works—posing risks to both the heritage fabric and the safety of the isolated worksite.
The Solution
To meet the technical and heritage requirements, the Polyroof Protec System was selected as the most appropriate waterproofing solution. Its cold-applied, fully bonded nature enabled installers to achieve a continuous, seamless membrane across the roof’s irregular geometry—something sheet-based systems could not achieve. The liquid application allowed Haran Roofing to fully encapsulate complex architectural features such as the foghorn drum and trumpet plinth, which were temporarily removed and reinstated to ensure absolute substrate contact and preservation of original detailing.
Before waterproofing, the team undertook essential remedial works to stabilise the concrete deck and remove defective layers. The compromised bituminous material was isolated using a Polyroof SA Foil-Faced Carrier Layer, providing a secure base for the Protec build-up while maintaining the integrity of the listed structure.
Protec’s RapidCure technology was a crucial factor in the island’s harsh climate, allowing work to progress reliably within short weather windows and providing instant, early-stage weatherproofing that protected the roof even before full cure. This capability prevented water ingress during sudden downpours and enabled phased installation that aligned with environmental conditions.
The tins of resin offered a practical advantage during transportation, avoiding the need to haul heavy rolls of felt or single-ply material across difficult terrain. The membrane’s resistance to ponding water, wind uplift, and long-term salt exposure ensured suitability for the severe maritime environment. All terminations, upstands, and outlets were dressed with the liquid membrane and finished into chases or lead flashings in line with BS 6229 requirements, whilst ensuring conformity with heritage requirements.
The Result
The completed refurbishment re-established the Foghorn Station’s watertight integrity while preserving the building’s historic character and ensuring its long-term resilience against the harsh coastal environment. The seamless Protec membrane created a visually sympathetic finish that complements the station’s white façade, retaining its original architectural identity without introducing visible fixings or interruptions. The light-grey waterproofing integrates discreetly with the industrial metalwork and restored foghorn components, enhancing the building’s crisp, heritage appearance.
The system’s monolithic nature ensured that every junction, penetration, and irregular surface was fully encapsulated—critical for a structure required to withstand high winds, salt-laden spray, and frequent weather changes. Its durability also helps protect against damage from seagulls and marine wildlife, an important consideration for exposed island sites.
Despite the logistical obstacles and unpredictable weather, the project was completed in just 20 days, demonstrating both Haran Roofing’s exceptional workmanship and the installation efficiency enabled by the Protec System. Waste was managed responsibly and transported off the island, and all detailing was completed in full accordance with heritage and environmental standards.
Today, the Foghorn Station continues to stand as a remarkable piece of Welsh coastal heritage. From its original construction in 1906, to its restoration by volunteers in the 1960s, to the celebratory reopening in 2000 with the first sounding of the horn since 1988, the refurbishment of the Foghorn Station is the latest development in this landmark’s rich heritage. The new Protec waterproofing system now safeguards this historic asset for the future, ensuring it remains both structurally protected and culturally significant for generations to come.
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