Once a popular honeymoon destination after it was acquired, repaired and re-opened by holiday camp pioneer, Billy Butlin in 1953, it is now the central building from which a development of luxury apartments takes its name along with four new build apartment blocks constructed within the grounds.
Every attention has been taken to preserve the original structure in line with its listed status and to design the new blocks in-keeping. However, problems with the integrity of the waterproofing system originally specified became apparent even before the scheme was completed, leading to a change of both roofing contractor and, eventually, roofing system.
Integrity issues
Both the existing hotel building and the new builds have flat roofs and architect, Rolfe Judd, had specified a liquid waterproofing membrane. Unfortunately, the system selected was not robust enough to adhere seamlessly to the roof substrate. The development’s coastal location required a more durable and flexible membrane that could withstand a moist and salty atmosphere, high UV levels and, most importantly, would adhere permanently to both the roof and all upstands and outlets.
When the integrity of the waterproofing membrane on the four new build structures was first compromised, however, the assumption was made that the issue lay with the quality of installation rather than the suitability of the membrane.
A new roofing contractor, Cawston Roofing, was brought in to carry out repairs to the membrane but, as the existing roof build up was still under warranty, Cawston Roofing was required to carry out repairs using the same product.
The majority of the problems with the roofing material were around the upstands. While repairs using the same membrane seemed to address the issue briefly, the same issues recurred following the repairs.
Kevin Cawston from Cawston Roofing comments: “It became clear that using the same system to repair the defects simply wasn’t going to work.
“At the same time, the project to refurbish the main hotel building was nearing completion and the main contractor was keen to find a solution for the four new build blocks that would also offer a permanent solution for the roof of the main building.”
Overlay strategy
Having used Kemper Systems’ Kemperol membranes on a wide variety of construction projects in the past, Cawston Roofing was confident in recommending Kemperol V210 cold liquid-applied waterproofing membrane. Rather than carry out additional repairs using Kemperol V210, the Kemperol V210 roof was installed as an overlay onto the existing failed membrane wherever possible and the existing was stripped out and replaced with Kemperol V210 where this was not viable.
The existing inverted roof build up for the new build apartment blocks had the originally specified membrane installed beneath the insulation. Cawston Roofing removed the paving slabs and green roof medium along with the insulation and, where possible, this was stored for re-use.
The company then prepared and cleaned the roof surface and, in the areas around the upstands where the failed membrane had not bonded, the team pulled off the damaged membrane.
The existing insulation, slabs and green roof medium were then reinstated to complete the roof.
As Kevin comments: “By the time we were carrying out the overlay of the failed membrane with the Kemperol V210 system the apartments in the four new blocks were already occupied.
“This meant that ease and speed of installation were essential to prevent any water ingress during the works and ensure that we completed each building with as little disruption to residents as possible.”
Cawston Roofing used the same process and materials for each of the new build terraces, but the damage caused by the failed waterproofing membrane on the roof and balconies of the former hotel building was even more significant because the original roof build-up was not inverted.
The balconies were tackled first, with strip out of the entire roof build-up. Here, not only had the originally specified membrane failed but the insulation below it had begun to rot too.
Having completed the strip out, Cawston Roofing allowed the concrete substrate to dry on each balcony and the decision was taken to reinstate the build-up for each balcony as an inverted warm roof.
Kevin explains: “New insulation had to be cut to size and shape. We were able to do this while the Kemperol V210 membrane was being installed so that we could complete the balconies as quickly as possible.”
Cawston roofing used the same primer, resin and fleece for the balconies of the refurbished hotel, allowing the system to cure before completing each balcony with new insulation and paving slabs or decking.
The team then moved onto the 8500m² former hotel roof, which comprises five ‘fingers’ with a central core. Water ingress around the roof outlets meant that the recently installed warm roof insulation was already sodden and the roof had to be stripped back to the vapour barrier.
To aid water run-off in the future, Kemper System designed a tapered Kempertherm insulation scheme, introducing a slight pitch to each section of roof. Cawston Roofing pre-primed each piece of board in an on-site workshop during the winter months to aid faster installation once the weather improved.
When weather conditions did improve, the Kempertherm sections were fixed to the substrate and joint sealed before application of the Kemperol V210 membrane began.
Holiday heritage
Thanks to the replacement of the originally specified waterproofing system with Kemperol V210, the building not only provides a stylish address on the coast that is warm and dry for residents but also protects a slice of the UK’s holidaymaking heritage.
