Work atop John Lennon Airport’s control tower posed big challenges for the contractor that demanded careful planning and product specification.
Working at height is intrinsic to any roof refurbishment and managing the risk is a crucial part of planning a project.
“With no scaffolding, access to the roof was directly through the air traffic control room via a hatch in the ceiling”
That process starts by understanding the specific challenges of the scheme in terms of height, access, locality and environmental conditions.
That was certainly the case when W Swindells & Son was commissioned to refurbish the air traffic control tower roof at Liverpool John Lennon Airport. The tower is both business and safety-critical, so a major part of the brief was to ensure there was no disruption to its 24/7 operation.
With airside airport restrictions preventing the use of scaffolding and presenting a challenging occupied work environment, the correct specification was essential.
To address this, the team selected Kemper System’s 2K-PUR, a cold liquid waterproofing resin which is odourless, solvent-free and applied wet-on-wet in a single process, backed by a BBA-accredited 25-year service life.
The first working at height advantage of this approach was that it avoided the need for any strip-out and removal of the existing bituminous surface, because the Kemperol 2K-PUR could be installed directly on top as an overlay. This not only avoided disruption from strip-out works but also reduced the programme and, the exposure to working at height.
John Lennon Airport Kemper Control Tower 3
With no scaffolding, access to the roof was directly through the air traffic control room via a hatch in the ceiling. All materials and equipment had to be transported to site in this way, which was another major advantage of using the liquid membrane.
A hot works-based system would have required cumbersome equipment and gas bottles to be brought up to site through the control room with their own associated risks, but the overlay required only the use of tubs of resin, brushes, rollers and rolls of lightweight reinforcement fleece.
It takes two
The small roof area and limited access meant W Swindells & Son assigned just a two-man team to the project, cutting the overall risk. The site was prepared with a bright yellow plastic netting attached to the safety rail around the tower’s perimeter to create a physical and visual boundary for the team and prevent any materials or equipment falling from the exposed rooftop.
”While the roof area was relatively small, there were considerable complexities in terms of detailing and terminations”
Following cleaning of the existing substrate, the team applied a primer and this was allowed to cure. The Kemperol 2K-PUR resin was applied section by section to the roof using rollers. The flexible reinforcement fleece was cut to size and shape on site and laid onto the wet resin.
The installation team then immediately applied more resin on top to fully saturate the fleece, removing air bubbles or creases with the rollers. The resin then cured to form a seamless, durable, UV-stable monolithic membrane.
On this project, while the roof area was relatively small, there were considerable complexities in terms of detailing and terminations. The Kemperol product’s ease of application, plus the various fleece widths and roll sizes available, allowed the team to work easily within the confined space of the walkway without the added risk of having to deal with cumbersome materials.
The control tower roof is a dodecagon shape with a hexagon structure in the centre and the fleece had to be cut to meet its exact angles on both sides, with flashings created by bringing the resin and the fleece up the parapet wall on one side and the central structure on the other.
The waterproofing system also had to accommodate numerous supports for the existing handrail around the roof’s perimeter and six existing ventilation outlets. Accordingly, an easy-to-use system was vital for minimising both the programme and work at height.
John Lennon Airport Kemper Control Tower 2
The solvent-free system also ensured that there were no nuisance odours within the control room during the works that might affect the operational efficiency or concentration of the air traffic controllers.
The project has even reduced the future working-at-height risk for airport maintenance teams after the team installed a central strip of Kemper’s Kemperdur TC anti-slip surfacing on the roof using anthracite-coloured quartz aggregate as the wearing course.
This finish was also applied to the section of the roof where access is gained from the control room, delivering a long-lasting solution for the client.
John Swindells is director of W Swindells & Son Roofing Contractors