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Captain Cook Square, Middlesbrough

Single ply overlay to a warm roof of a shopping centre
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The existing roof waterproofing at Captain Cook Square shopping centre in Middlesbrough comprised a failing 20 year old single-ply membrane. The client required a long term solution which could be tested for compatibility with the single ply and allow overlay with the minimum of disruption.
Location
Middlesbrough
Completion
2020
Area
6,500m²
Authorised Contractor
Central Roofing & Building Services Ltd

The challenge

Captain Cook Square Before Triflex

In July 2017, Tom Walker of Jones Lang LaSalle invited Triflex to carry out a site survey of the 6,500m² roof at the Captain Cook Square shopping centre in Middlesbrough.

The existing waterproofing comprised of a 20 year old PVC single-ply membrane which was at the end of its service life, deteriorating generally with visible splits at the laps and in detailed areas. These issues can be common in all single-ply roofs that are near the end of their life and particularly common in plasticised membranes. Years of exposure to UV, thermal cycling and weathering can cause shrinkage and tension in the membrane, which will focus on weaknesses in laps, seams and at details. Without a new waterproofing membrane it was clear that further water ingress would occur and likely cause damage to the retail outlets below.

A full and detailed on-site investigation was carried out by the Triflex Field Technician Team. During the investigations a number of tests were conducted to aid the specification process, including core tests, peel adhesion tests and the removal of samples for laboratory plasticiser migration tests.

Core tests involve carefully removing a ‘core’ or section from the roof to establish the existing roofs build-up above the primary substrate. It allows us to reveal whether the build-up is consistent across a number of core locations, whether there are any underlying or undetected issues and allows indicative calculations to determine whether there is a condensation risk and the approximate U-Value of the existing build-up . In this case the build-up consisted of a concrete deck, PIR insulation and the approximately 1.2mm thick single-ply waterproofing membrane. The cores revealed that the insulation was still in a good condition and would not require replacement.

In the majority of instances, and based on testing literally thousands of membranes, Triflex system are fully compatible with single-ply membranes and can be used to overlay them, avoiding the costs, risks and disruption of removal. Experience has confirmed that even if the membrane is known and has been tested previously, differences in formulation of the single ply membrane overtime make it essential to carry out adhesion tests in each and every case. These tests are designed to confirm the required preparation, pre-treatment and priming method, although in many cases all that is required is a simple clean before applying the Triflex waterproofing system. In this case, on-site peel strength adhesion tests which due to the exceptionally rapid curing of our products give results after just one hour, showed that the single ply membrane was suitable for overlay directly after simple cleaning and with no primer.

A small amount of the existing single-ply membrane from various locations was also removed for off-site plasticiser migration tests. These samples were sent to the Triflex Research and Development Centre in Germany for laboratory testing, a process which takes approximately 5 weeks to complete. The tests simulate accelerated ageing of the single ply and determine the level (if any) of plasticiser migration over time both as a control and when in direct contact with the specific Triflex membrane used for the overlay. These tests also include testing the physical properties of the single-ply membrane after ageing and forced plasticiser migration to ensure that the membrane to be overlaid provides a long term, stable substrate. This attention to detail has allowed Triflex to gain the best reputation in the industry for the direct overlay of single ply membranes with our oldest UK PVC overlay project (12,000m2) carried out in 2002 and still performing without issue.

The solution

Captain Cook Square After Triflex

One year after the testing had been completed, Jones Lang LaSalle confirmed that funding for the project had been received. Thanks to the in-depth survey and testing provided, Triflex were invited to present a project specification proposal for the roof overlay based on the findings of our testing. At this point Triflex Authorised Contracting Partners, Central Roofing and Building Services Ltd. were brought on to the project.

Prior to conducting the works, Central Roofing and Building Services Ltd. carried out their own pre-construction drone survey. This coupled with the Triflex project specification proposal provided the client with a thorough understanding of the scope of the project and additional faith in the installation process proposed.

The solvent-free Triflex ProTect system was specified to overlay the single-ply roof. Triflex ProTect is a fully fleece reinforced system based on the most advanced PMMA resins. The BBA and ETA certified system is fully compatible with single-ply membranes and provides a seamless, reliable waterproofing membrane proven to perform on this challenging substrate. The system is totally cold applied, rapid curing, including being rainproof in as little as 30 minutes and can be installed in temperatures down to 0°C allowing works to be completed throughout the cold winter months.

Detailed areas needed a specialist solution. The solvent-free Triflex ProDetail and Triflex ProFibre were specified to waterproof all details and penetrations. Triflex ProDetail is a fleece reinforced system, with a thixotropic formula that allows it to be installed onto vertical surfaces and is ideal for waterproofing upstands, gutters and roof penetrations. Triflex ProFibre is a detailing waterproofing system that contains individual fibres within the resin, when applied they interlock to provide additional tensile strength and resilience. It is ideally suited to extremely complex details and those that are difficult to access.

On-site works commended in late 2019, with the rapid curing of the Triflex materials and suitability to be installed in low temperatures without an extension of cure time helping to keep the project on track. James Bartlett of Central Roofing & Building Services Ltd. commented “The Triflex waterproofing systems were easy to install and this helped to keep the project on track. The support provided by the team at Triflex is exceptional and this added to the smooth running of the job in order to complete it within the time scales and working parameters. This product was very effective for a single ply roof and I look forward to using it again on other projects. I would highly recommend using Triflex in the future.”

Captain Cook Square Triflex ProDetail

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