Nexus Apartments, Watford

Single-ply overlay of private apartments
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The 600m² single-ply, tapered warm roof system at Nexus Apartments had showed evidence of water ingress from the start. The client were looking for a supplier that could be trusted to find the right flame free solution, that wouldn't require the removal of the existing single-ply membrane and would cause minimum disruption to the residents.
Authorised Contractor
Mulberry GBC Ltd.

The challenge

Nexus apartments before Triflex

Triflex were invited to provide a project specification proposal for a waterproofing solution to roofs 1, 2, 4 and 6 of the Nexus Apartments in Watford. The existing roof areas were over 600m² and consisted of a single-ply tapered warm roof system on a metal deck which had been installed during the construction of the new build apartments 2 years’ prior. The client Careys PLC stated that the existing single-ply waterproofing membrane had never provided sufficient waterproofing and showed evidence of water ingress from the start.

The Triflex Field Technician team conducted core tests to the roofs to establish the build-up and determine whether moisture was present within the existing insulation.

Peel adhesion tests were also undertaken to ensure a strong bond could be achieved between the single-ply and the Triflex. These tests identify whether any pre-treatment or priming is required prior to the application of the Triflex waterproofing resins. Lastly, a single-ply sample was taken to be tested for 6 weeks in the Triflex Laboratory for plasticiser migration.

Two of the roofs contained numerous PV panels. These roofs required particular consideration to ensure that the replacement waterproofing system would be strong enough to withstand the weight of the panels without puncturing the membrane, in these locations a heavy duty finish would be required. The roof also contained areas which would require intricate detailing, including a party wall, upstands, door thresholds, internal gutters, chute outlets and penetrations.

Careys stated that the proposed solution would need to be flame-free and suitable to directly overlay the existing single-ply. By doing so this would reduce the cost and time of removal, the disruption to residents and ensure that any risks associated with the use of hot works would be completely negated.

The solution

Nexus apartments roof renovation

Triflex were the specified solution due to the comprehensive testing that was conducted, the care and attention to detail that was provided and the systems’ ability to directly overlay the existing single-ply membrane.

Testing revealed that the existing build-up was still in good condition apart from the apparent leaks, but the original insulation wasn’t wet or sodden and would not require replacement. Triflex was compatible with the existing single-ply ensuring high levels of adhesion could be achieved, and there were no signs of plasticiser migration.

Authorised Contracting Partners, Mulberry GBC Ltd. were brought onto site to carry out the installation. The specified system, Triflex ProTect provided the main area waterproofing, and Triflex ProDetail was used to waterproof all detailed areas, including upstands, penetrations and gutters.

Both systems are completely cold liquid applied, requiring no use of hot works throughout installation, are rainproof in 30 minutes and fully cured within one hour. They are BBA and ETA certified to provide a durable roof waterproofing service life in excess of 25 years, highly durable and are rapid to install thanks to their simple wet-on-wet installation process.

Triflex ProTect and Triflex ProDetail are hydrolysis resistant, meaning that they won’t be broken down when submerged in standing water, which can be common on flat roofs, they can also be tailored to include a smooth or heavy duty finish. The heavy duty variant of Triflex ProTect which uses an embedment layer of Triflex ProTect with Triflex Quartz followed by a layer of Triflex Cryl Finish 205 was specified for use beneath the PV panels. This ensured that movement and point loading from the weight of the PV panels would not puncture or damage the waterproofing membrane.

Works were conducted during August 2019 and were completed to schedule. The finished roofs should provide a reliable and lasting waterproofing membrane to the Nexus Apartments for many years to come.

Nexus apartments after Triflex