THE BARGATE, SOUTHAMPTON
Project Overview
IKO, in partnership with James Roofing Limited, delivered a heritage waterproofing solution for The Bargate, a Grade I-listed gatehouse and part of Southampton’s medieval city wall. Built in 1180 as the original entrance to the city, it is widely regarded as ‘the finest and most complex town gateway in Britain’ and attracts thousands of visitors each year.
Adjoining the gatehouse are the Southampton Walls, constructed in the 1360s in response to a devastating pirate attack. These fortifications are believed to be the first in Britain designed to incorporate the emerging defensive technologies of gunpowder and cannon, marking a pivotal point in the evolution of British military architecture.
A defining landmark of Southampton’s heritage, The Bargate required expert restoration that could uphold its historical integrity while delivering a durable, modern waterproofing solution. With strict oversight from English Heritage, the conservation brief presented a complex and highly sensitive challenge.
Challenges
The Bargate project presented several unique and complex challenges, primarily due to the historical significance and physical condition of the structure. As a monument dating back to the 10th and 14th centuries, every aspect of the restoration required careful planning, specialist knowledge and exceptional craftsmanship.
One of the primary challenges was the need to remove the 50-year old asphalt without causing any damage to the underlying medieval stonework. The structure’s age and fragility demanded specific techniques and a delicate, manual approach. Any impact to the original fabric of the structure could have jeopardised both the conservation objectives and compliance with strict English Heritage requirements.
Weather was another critical factor. Mastic asphalt requires specific environmental conditions for correct application. Intermittent rainfall and fluctuating temperatures meant the installation team had to monitor conditions closely and adapt their schedule daily. Work was paused during unsuitable weather and protective measures were implemented to safeguard quality and ensure the long-term performance of the system.
The complexity of the structure itself added further difficulty. The Bargate features uneven surfaces, intricate detailing and varying gradients, all of which required a highly flexible, seamless waterproofing solution.
Coordination among stakeholders was also crucial to success. With multiple parties involved, James Roofing Ltd, principal contractor Payestone, the Southampton Heritage Department and IKO, regular communication and close collaboration were essential.
Solution
The existing asphalt structure, first laid in 1973, had reached the end of its service life. James Roofing Limited was appointed to upgrade the waterproofing system in line with stringent heritage preservation standards. Working alongside principal contractor Payestone and the Southampton Heritage Department, the team removed the original asphalt with precision and installed a new IKO Permaphalt mastic asphalt roofing system with 10–15% added grit to improve durability and aesthetics in keeping with the site’s historic character.
IKO Permaphalt was chosen as the ideal solution for this restoration due to its temperature stability, flexibility and fatigue resistance – attributes achieved through advanced polymer technology. Designed to meet modern technological standards, IKO Permaphalt delivers seamless waterproofing that can adapt to the complex contours often found in historic masonry. Crucially, it maintains the visual integrity required by conservation authorities while significantly enhancing long-term performance.
In addition to its technical merits, IKO Permaphalt supports sustainability objectives vital to public sector and heritage-funded projects. With complete supply chain control, locally sourced raw materials and UK-based manufacturing, the system’s environmental credentials strengthened its suitability for a sensitive restoration such as The Bargate. When delivered in blocks, it comes packaged in the UK’s first waste free wrapper, helping to minimise on-site waste packaging disposal and contribute to responsible roofing practices.
Despite these challenges, the project was delivered on time and to the highest standard. The result is a waterproofing system that not only protects this historic landmark, but also respects its architectural integrity, demonstrating how modern materials like IKO Permaphalt can be successfully integrated into heritage conservation with the right expertise and sympathetic oversight.
Project name and location:
The Bargate, Southampton
Project sector:
Heritage
Contractors: