Sandown Court, Preston

A new warm roof waterproofing system for a flat roof
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A high-rise block of apartments in the centre of Preston was in urgent need of a new warm roof waterproofing system for its flat roof.
September 2020
Authorised Contractor
Permicoat Ltd


A high-rise block of apartments in the centre of Preston was in urgent need of a new warm roof waterproofing system for its flat roof as the existing waterproofing system had comprehensively failed, resulting in the penthouse suite experiencing localised flooding.

The Challenge

Triflex Authorised Contractors, Permicoat Ltd were tasked to provide an in-depth specification for replacing the failing waterproofing system and improving the thermal performance of the build-up. Considering the logistics of installing a new system on a high-rise tower block where access was challenging, Permicoat Ltd needed materials that were lightweight and easy to transport from ground level. The removal and disposal of the old waterproofing system could also prove difficult on such a tall building. Limiting the risk of exposure to water ingress during the works was also a prime consideration.

Following thorough investigations from Permicoat Ltd and Triflex, the build-up of the current system was established. This consisted of a structural concrete deck, mastic asphalt, an unknown liquid coating, 80mm thick PIR insulation and a further unknown liquid coating. As part of the condition survey and core testing, the existing roof build up was found to be delaminating and blistering was evident in several areas. With an indicative U-value of 0.24 W/m²K, the existing warm roof did not meet current Building Regulations, and due to its poor state, needed to be replaced.

James, Commercial Director from Permicoat Ltd says, “After the initial site visit and roof survey of Sandown court it was clear that the roof was in desperate need of some major works. The existing roof was installed around 6 years ago and was possibly in the worst state I or my colleagues had seen a roof.

The complete roofing membrane and underlying insulation had de-bonded in its entirety from the concrete slab deck with other areas where the membrane was peeling away.”

The Solution

Sustainable option to reduce wastage and improve thermal performance

A Triflex ProTect warm roof was specified to meet the requirements of the current Building Regulations for Existing Dwellings: Approved Document L1B; i.e. a U-value of 0.18 W/m2K. Because the Triflex ProTect system was compatible with all of the existing substrates, different options were possible to provide a seamless, reliable waterproofing membrane. Whilst one option was to remove all the existing build up to the underlying concrete, and then apply the Triflex ProTect warm roof system, an alternative was also proposed. The second option was based on reducing costs, reducing waste to landfill and minimising the risks of water ingress during the works. Here, the existing asphalt layer could be used as a robust vapour control layer providing a more sustainable and cost-effective choice, whilst protecting the structure from water ingress during the works. This was under the proviso that once exposed, the in-situ mastic asphalt was in suitable condition to receive the new Triflex warm roof build-up and would be repaired where this was not the case.

As the programme of works commenced, Permicoat Ltd removed the existing coating and insulation. In conjunction with Triflex, it was confirmed that the majority of the existing asphalt was in a sound condition and as a result would provide a suitable vapour control layer. In the limited areas where the asphalt was defective, this was removed. Here, a self-adhesive Triflex Vapour Control Layer was installed to ensure a continuous layer of protection to the fabric of the building. New insulation to provide a warm roof to meet current building regulations was then installed using Triflex Insulation Adhesive. The insulation was then rapidly protected and made watertight using a self-adhesive Triflex Carrier Membrane. Lastly, Triflex ProTect, a wet-on-wet applied, fleece fabric reinforced waterproofing was installed quickly and efficiently thanks to the exceptionally rapid curing capability of the PMMA-based system.

Details and penetrations easily accommodated

Detailing including upstands and penetrations required a tailored specialist solution. Triflex ProDetail and Triflex ProFibre were specified to provide to deal with these issues. Triflex ProDetail is also a fleece fabric reinforced, wet-on-wet application system. Its thixotropic formula allows it to be installed onto vertical and even inverted surfaces without fear of ‘slumping’ or product loss. For more complex details and those with restricted access, Triflex ProFibre was proposed as it contains individual re-enforcement fibres within its resin body, making it easier to apply with a brush. The individual fibres interlock to provide additional tensile strength and re-enforcement to the elastomeric resin.

Maximising efficiency and weather windows 

All Triflex resins are contained in tins, enabling them to be easily and safely transported to roof level. The systems specified are all cold applied and rapid curing which allows works to be completed in tight programmes. Permicoat Ltd were able to apply the waterproofing within weather windows as Triflex ProTect is rainproof in as little as 30 minutes. During the project, Permicoat Ltd also showcased their skills and demonstrated the products’ capabilities by adding a Triflex Logo to the installation for visual effect.

Works were completed to programme by September 2020 with a high level of workmanship. The finished high-rise warm roof system providing a reliable and long lasting waterproofing to the Sandown Court Apartments for many years to come.

“Our client expressed their disappointment in the way that the original product manufacturer and installing contractor had failed to offer any form of support. Naturally, our client requested an alternative solution to that previously installed. Triflex was the chosen product because we know of the superb back-up that we can expect to receive from Triflex and that the Triflex ProTect system is one that we believe to be one of the best in the market.”
Triflex and Permicoat met together with the Sandown Court Management committee to talk them through the entire process, from the initial findings during the site survey, proposed specification, technical support and how the works would be monitored by both Permicoat management and Triflex. We thoroughly enjoyed working on this project with Triflex and think that the finished project looks fantastic.”

James, Commercial Director, Permicoat Ltd


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