Background 

Picture this: a plethora of dynamic texture and colour sprawling across a 1,120m² roof, sits an abundance of luscious green roof sedum, bountifully accented with carefully placed pebbles. Situated against the backdrop of rural Blackwood, Caerphilly in the Ebbw River valley, this vast green roof integrates seamlessly with the surrounding foliage, contributing to the aesthetical appeal of the neighbouring Welsh valleys. However, what lies beneath this picturesque scene is a highly complex roofing project, which required consistently high levels of communication and collaboration between all stakeholders to ensure the Client’s needs were met in an efficient yet effective manner.

The Challenge

Operating from the Penyfan Industrial Estate in Newport, Wales, KPMF is a premium quality manufacturer of self-adhesive vinyl films, having been long-standing contenders in the production of vehicle marking films since 1991. Due to exponential growth in recent years, KPMF was ultimately burdened with the restrictions of too small a warehouse, subsequently requiring significant expansion to cater to their vast manufacturing operations. Polyroof Approved Contractor, Haran Roofing Ltd were approached in relation to the construction of a bespoke green roof system, who in turn collaborated with Polyroof to find the most appropriate solution, utilising their advanced liquid roofing technology. Polyroof subsequently looked towards Wallbarn, who supply innovative green roof technology for use in the construction industry, ultimately utilising their M-Tray System, which consists of specially-designed modular trays containing superior, engineered substrate and fully established flowering sedum.

Polyroof’s range of liquid waterproofing systems are renowned for being the ideal green roof base, owing to their seamless, lightweight, maintenance-free, and long-lasting properties. Being highly root resistant when installed as part of a green roof system, this negates the need for additional root barrier layers, thus keeping the weight of the solution to a minimum. The membranes are also flexible enough to easily accommodate structural movement, therefore, further enhancing their suitability for installation in conjunction with green roof systems. This made Polyroof’s advanced liquid roofing technology the ideal choice for the KPMF project, due to the size of the green roof that would subsequently be installed atop of the membrane, providing a durable, robust base that would protect the integrity of the roof structure.

The Solution

Taking into account the client’s complex requirements for a thermally efficient roof structure to sit below the intricately designed yet significantly sized green roof, Haran Roofing specified a full Polyroof Built Up Roof (BUR) solution for the new build project at KPMF, owing to their strong relationship with Polyroof and their system compatibility with green roof systems. A steel hard edge was fitted to all exposed perimeter edges of the roof at 300-400mm centres into the roof’s metal deck, secured to the structure using screw fixings, which would ultimately ensure the roof’s insulation would not move.

Following the application of the Polyroof SA Primer, the SA Vapour Barrier was installed to encapsulate the insulation boards at all abutments, penetrations, and exposed edges, preparing the surface for the Polyroof Tissue-Therm Insulation. This is a high-performance tissue-faced PIR insulation with square edge joints that is ideal for use with the Polyroof SA Carrier Layer, which was subsequently applied on top of the insulation. The insulation within the Protec Warm Roof’s build up played a key role in the KPMF project to help meet the Client’s sustainability goals, as it worked in harmony with the waterproofing membrane and ancillaries to provide a thermally efficient, roofing solution that can ultimately contribute to lowering energy bills and subsequently reduce carbon footprint.

The Protec System was specified by Haran Roofing as the waterproofing membrane for the roof, to achieve long-lasting protection for the KPMF storage facility. Protec is a highly versatile, fast curing, fully reinforced, cold liquid-applied membrane system, ideal for a wide range of flat roofing and waterproofing applications. Complete with RapidCure technology for extremely fast installation, boasting cure times of as little as 30 minutes, this ensures minimal downtime and disruption to commercial operations. Due to the client’s tight turnaround requirements, this was a key consideration for Haran Roofing when specifying the BUR system, as it solved the challenge of what could otherwise have been a much longer installation timeframe. Compatible with Polyroof’s summer inhibitor technology, this enabled the Protec System to be installed throughout the warmer summer period, allowing for greater control over the speed of cure depending on the outdoor temperature.

The primary challenge in relation to the roofing project at KPMF’s new storage facility was the intricate detail designs that were required as a result of the specified green roof. This was eased by the installation of the modular green roof as opposed to a rollout system, which consists of specially designed modular trays containing superior, engineered substrate with fully established sedum that easily click together to form a seamless green roof. The modular nature of the system helped to mitigate the complex nature of the project, enabling a much faster, cleaner, and easier installation process for the installers. Additionally, as the sedum was pre-grown, it also presented significant benefits over a rollout green roof system as the plants were already fully established and mature, being fully rooted into the substrate. This ultimately enabled an instant green roof to be achieved, perfectly suiting the Client’s strict timeframe. The suitability of the modular system was further heightened by its ease of removal without causing damage to the green roof, ensuring sufficient accessibility to the waterproofing membrane below should any future inspection or maintenance be required.

The green roof system installed contained 12 different species of flowering and Northern European sedum to provide a variety of leaf structures and colours. The increased diversity of plants will subsequently attract a greater number of birds and insects, thus providing a natural habitat in which for them to reside and contributing to increased biodiversity. As well as absorbing approximately 50% of water during rainfall, by having to pass through the substrate the passage of rainwater into the drainage system is delayed for up to one hour, meaning far less pressure is placed onto the drainage system. Another benefit of incorporating the modular green roof system into the KPMF storage facility roof, is the low maintenance required. The sedum is extremely robust and drought tolerant, therefore, it remains green during winter and generally does not require an irrigation system during the summer. This will benefit the Client significantly over the course of the roof’s lifetime, mitigating the need for maintenance procedures to the sedum.

Originally, 4,237 trays of green roof sedum were specified for the installation, however, the total was later decreased to 4,185 trays, due to requiring the addition of a fire break. Each green roof sedum tray measured 500 (length) x 500 (width) x 100 (depth). This presented a significant task for the contractors, as each tray had to be manually installed on top of the waterproofing system. Due to the roof’s 10-degree pitch and significant weight of the green roof system, Haran Roofing had to take these implications into consideration, therefore, realising that sufficient support measures would need to be implemented to ensure the roof remains structurally sound throughout its service life. To provide adequate support to the roof, in particular to the aluminium green roof edging trims, a series of bespoke 75x50mm timber battens were installed 150mm from the perimeter of the roof, mechanically fixed into the steel substrate and fully encapsulated within the Protec System. This was due to concerns raised around the angle of the pitched roof, as this posed risks in relation to movement of the green roof system and pebbles. The sheer complexity of this challenge was combatted through bespoke designs created by the Polyroof technical team, which outlined in a highly detailed format how the battens would support the weight of the modular green roof.

Another challenge that remained constant throughout the roofing project was the live operational environment in which the installation took place. This required a high level of organisation from Haran Roofing and the relevant third parties to ensure the project didn’t have a detrimental effect on KPMF’s operations. By remaining in constant communication with the site representatives along with assistance from the Polyroof technical and field teams, this resulted in a seamless installation of the Protec Warm Roof System and accompanying modular green roof system.

Health and safety were a priority throughout the duration of the project, necessitated further by the pitched angle of the roof. Therefore, following the appropriate risk assessment to identify any potential risks and to ensure safety for those working at height during installation, a number of measures were enacted to provide adequate protection, including temporary barriers and relevant PPE. A collaborative approach was maintained by Polyroof, Haran Roofing, and KPMF at each stage of the project, going above and beyond to ensure the wellbeing of the installers was maintained and that all work met the specified standards for the Client.

The Result

Despite the technical and logistical challenges encountered during the installation, the result of the KPMF project was an outstanding success. All challenges were managed effectively by the project team, with the collaboration between Polyroof, Haran Roofing, and Wallbarn ensuring that the system installation was completed according to specification, exceeding the client’s requirements for an efficient yet robust waterproofing solution that resulted in very little downtime. The application of the Protec Warm Roof System has provided thermally efficient, waterproof protection that will service the KPMF storage facility for many years to come. Complete with a BBA durability rating of at least 30 years, KPMF can rest assured that their operations can continue safe in knowledge that the roof above the new facility is robust and long-lasting.  Accompanied by the modular green roof, the finished result exudes an air of architectural modernity, enhancing the aesthetical appeal to the structure and blending seamlessly with the building’s surroundings.