Waterproofing performance from ARBOFLEX® PU for greener city living

The long-term performance and integrity of any roof covering are essential parts of constructing a sustainable and low maintenance building. But when the waterproofing is installed as a buried system, with finishes included green roofs, solar panels and porcelain terrace areas, installation values and product performance are more important than ever.

That’s why the ARBOFLEX® PU liquid applied waterproofing system from Carlisle Construction Materials was chosen for Park Avenue Place at Neptune Wharf; a residential development comprising nine apartment blocks, surrounding a landscaped podium deck communal area. The prestigious project in Deptford, East London, led by Galliard Homes, features 176 luxury flats and forms part of a wider regeneration programme.

Consistent installation
The roofing project was delivered by T & T Roofing Limited, and leveraged the ease and speed of installation benefits of ARBOFLEX® PU; a single component liquid applied waterproofing system with proven root resistance. For this project, the core 10 year system was completed with the application of a U/V resistant top coat, applied to deliver a 20 year warrantied installation.

The ARBOFLEX® PU system was used as part of a complete roof build-up supplied by Carlisle for the roofs, terraces, and balconies of all the development’s apartment blocks, along with the podium deck and the planters.

The roof build-up for each building included a consistent sequence of layers, beginning with Carlisle’s ALUTRIX® vapour barrier membrane, tapered fire-retardant rockwool Multifix insulation, and the ARBOFLEX® Liquid Carrier Membrane, prior to application of the ARBOFLEX® PU liquid-applied waterproofing.

Working flexibly around the main contractor’s programme and other trades on site, the roofing contractor monitored the deck temperature each day, to ensure optimised performance of the liquid-applied roofing system. The ARBOFLEX® PU system was rollered onto the roof surface, and the system’s glass fibre membrane was laid onto the wet roof covering. A clean roller was then used to draw the liquid through the mesh. This provides a quality assurance check to verify that the correct amount of liquid has been applied. The mesh is submerged by the liquid waterproofing to a minimum thickness of 1.5mm and, once the liquid has cured, the system provides a seamless surface. The U/V resistant top coat can then be applied to achieve the BBA-accredited 20 year warranty.

For the upstands, parapet walls and vertical surfaces of the planters in the communal outdoor areas, the T & T Roofing Limited team added ARBOFLEX® Thickener to the ARBOFLEX® PU system, which provides thixotropic properties to the liquid system, ensuring excellent coverage for vertical surfaces.

Quality assurance
Following completion of each roof area, the T & T Roofing Limited team used leak detection technology to check the integrity of the installation. The equipment passes electrical current into the roof build-up, triggering an alarm if any water ingress is detected. The ARBOFLEX® PU waterproofing system used includes a conductive backing in the form of a foil-faced carrier membrane and vapour control layer. This allowed the installation team to test each installed area for pinholes and porosity using a high-voltage Holliday detector, by passing a high voltage current across the surface using a brush or roller electrode, ensuring the integrity of the roof covering prior to installation of the green roofs, solar panels and terrace finishes.

Further quality assurance for the installation was underpinned by the collaborative relationship between Carlisle and T & T Roofing Limited, with on-site training in the use of the ARBOFLEX® PU system provided by Carlisle, along with regular technical inspections.

Supplier support
To support T & T Roofing Limited in delivering the project on time and on budget across such a complex project, Carlisle worked collaboratively with the contractor to provide both efficient product supply and cost certainty. Carlisle’s operational support involved providing a UK stock holding, allowing for efficient and timely supply of the liquid applied waterproofing, insulation, and ancillary products.

This mitigated the potential impact of price volatility by enabling early procurement, with materials stored securely until they were drawn down for deployment. This approach not only contributed to cost predictability for the project but also demonstrated a proactive effort to manage financial considerations and enhance project efficiency.

Sustainable development
Following the installation of the ARBOFLEX® PU roofing system, the green roofs, comprising a build-up of protection layer, drainage board, fleece layer, biodiverse planting substrate, cobbled borders, and an aluminium trim, was installed on each roof area. Renewable power for the apartments is provided by ballasted solar PV installations. These green areas, along with hard and soft landscaping on the podium deck to create a communal garden, ensures the development offers exceptional build quality, aesthetics and environmental credentials, creating a contemporary and sustainable living environment in East London.