Multiple Bonded Warehouse’s
Replacement Roofing
Bonded Warehouse Roofing Client
Our client’s maturation warehouse operation stores whisky while it matures to the right age, producing many world-famous Scotch whiskies. Maturation is the process of leaving a spirit in a cask for a certain period (minimum three years for Scotch whisky) to extract flavour and colour. Having previously presented our portfolio of commercial construction solutions to the client, Starfish Construction showcased a range of successful commercial roofing projects within the food & drink sector. Our previous experience resonated with their property manager, who invited Starfish Construction to the tender for a project to manage all aspects of the design and installation of a new roof on two bonded warehouses (Warehouse 1 & 2) and the licenced asbestos removal from below the roof. The project was undertaken by our Industrial Roofing Division, supported by our Technical and Design team and working in conjunction with our Scaffolding Division and SEAS, our Licenced Asbestos and Environmental Management Division.
The tender was structured to allow the client to ascertain the type, capacity, associated costs and technical capability of the organisations invited into the process. The client would select the preferred contractor from an evaluation matrix based on their submission.
Commercial Roofing Project - Scope of Works
The warehouse roofs had reached the end of their service life, necessitating a comprehensive replacement project. This project encompassed a series of upgrades, including the roof sheets of Warehouse 1 & 2 to prevent water ingress, condensation, and corrosion and improve the ridge to preserve existing ventilation levels, ensuring at least 1% free air openings. Starfish Construction evaluated the gutters and linings for upgrading or replacement and any necessary redesign. Similarly, internal and external flashings were to be upgraded or replaced and planned improvements to the existing roof access systems to facilitate maintenance access from the ground to all gutters. The roof’s fall protection system was also to be upgraded to improve future maintenance safety.
The project scope included assessing any defective roof support structures and proposing rectification. A maintenance schedule and work instruction risk assessments were also provided, and the upgrades would also extend to the rainwater downpipes. Our Starfish Construction Group sister company, Starfish Environmental and Asbestos Services (SEAS), licensed asbestos contractors, would work as part of the scope of works to remove the Asbestos insulating board (AIB) under roof liner panels before the roof’s upgrade.
Turnkey Construction Divisions Ensure Value and Synergy
To allow for the submission of a vigorous, well-costed tender, Starfish Construction carried out the following components to support our tender submission:
- Structural calculations of existing roof steelwork
- The design of new purlins and spacings required a new composite roof that would allow for maintenance traffic and perform adequately to alleviate the risk of condensation
- Condensation risk analysis of the proposed roof sheet and demonstration that the proposed roof sheet would not permit condensation to form, eliminating potential water damage to the newly installed galvanised roof purlins and the casks stored within the warehouse
- Ventilation calculations and design of an appropriate ridge ventilation system would provide a minimum of 1% airflow based on the volume of the warehouse
- Use rainfall index calculations to ensure the gutters can manage the modern rain intensity—calculations based on a 1 in 50-year event
- The proposed installation of a Fall Protection system to facilitate future maintenance, with a design layout of the proposed system developed as part of the process.
In-house commercial roofing design capability
Starfish Construction’s in-house design team analysed the proposed bonded warehouse roofing solution, including a Condensation Risk Analysis to determine the dew point. They also considered the resilience of our gutter system design by performing capacity calculations to assess its ability to handle a 1 in 50-year CAT 3 rainfall intensity event. In our assessment of rooflight requirements, we made recommendations based on the potential loss of ethanol through the rooflights and the fully racked warehouse setup. Consequently, we proposed that there was no need for rooflights, which ensures cost savings for our client and addresses potential issues.
Furthermore, our evaluation of the existing low and high-level ventilation systems revealed the potential for a ‘stack effect’ within the warehouse. To optimise ventilation, we designed a ridge ventilation system covering 2% of the roof area, well within the recommended range of 1-3%, ensuring proper air circulation and environmental conditions within the warehouse.
Safe To Work Report
We undertook A Safe System of Work Report. Across both warehouses, scenarios requiring different safety systems were simulated to be incorporated. These included:
- Perimeter top lift scaffold to the leading edge of the eaves
- Bolted on roof edge protection to the roof verges
- Fully tensioned walkable safety netting above palletised casks
- Installation of a fully boarded platform on rack & tier cask storage, including the erection of lightweight working platforms built to the underside of the roof, providing a safe working platform for the roof removal
- AIB removal works - Installation of a full scaffold within the palletised cell to facilitate the subsequent licenced enclosure to allow for the asbestos removal
- Scaffolding & Access was carried out by Starfish Access Services Ltd (SAS), our in-house division and National Association of Scaffolding Contractors (NASC) Division members
- Asbestos Removal – Carried out by SEAS (Starfish Environmental & Asbestos).
- Starfish Construction took on the role of Principal Designer and Contractor
- Upgrade or replacement of gutters & linings as required
- Re-design and upgrade of rainwater down pipes
- Upgrade or replacement of internal and external flashings
- Upgrade of current roof fall protection system
- Group licensed asbestos contractor SEAS to undertake the removal of the AIB
- Completed budget and schedule, emphasising safety within a COMAH site
- Positive client feedback led to further AIB Asbestos removal project
12 Months
Duration
12,000 m2
Roof Replacement Area
Importance of Structural Engineering
The initial step in our comprehensive project planning involved appointing a structural engineer to conduct a thorough assessment. Their responsibilities encompassed evaluating the condition of the existing primary and secondary steelwork, which is crucial for ensuring the project’s structural integrity. Additionally, we entrusted the engineer with the critical task of performing snow and point-loading calculations. These calculations were essential in determining the precise spacing required for the purlins to determine the appropriate thickness of the roof sheeting–these critical components would guarantee the roof’s durability and resilience.
Furthermore, we based our decision-making process regarding the thickness of the roof sheets on data from a Scotch Whisky Research Institute report, which provided valuable insights into optimising U-values to minimise ethanol loss. This information was instrumental in guiding our approach to insulation. The report highlighted a delicate balance: no insulation led to increased ethanol loss, while too much insulation proved unnecessary with negligible benefits. By incorporating these findings into our design, we ensured that our roof sheet specifications were both environmentally efficient and economically viable for our client’s needs.
Commercial Roofing Project Success
In addition to the design and engineering challenges, working at height and within a COMAH (Control of Major Accident Hazards) site presents an ambitious undertaking for any company, whereby controlling and managing these additional critical factors is paramount. Starfish Construction was delighted to complete this roofing project without any accidents or incidents, another testament to the robust systems and procedures managed by our in-house HSQE division.
Starfish Construction has been highly encouraged by the client’s interaction on this project, and their involvement in the delivery process and proactive attendance at weekly progress meetings have allowed for excellent communication throughout the project and a successful outcome. We continue to grow our relationship with the client and we were delighted to secure another project carrying out licensed asbestos removal.
To be chosen as the Principal Contractor with the design responsibility to deliver these whisky-bonded warehouse roof upgrades on behalf of the client was the ideal position for Starfish Construction. From the outset, it was a very encouraging project to be involved in, whereby we demonstrated our experience and capability by delivering a fully detailed and designed tender bid showcasing our ability to take on board the client’s requirements, structure a solution, and present additional recommendations for further enhancements.
This roofing project success provided an opportunity for Starfish Construction to demonstrate our experience and expertise and showcase our collective company division’s dedication and commitment to manage the end-to-end process of a project of this magnitude. Having undertaken all the design in-house for the project, we had a clear understanding of the works and, therefore, were able to deliver the works safely, to the client’s expectations and within the programme. We look forward to continuing to build a sustainable, effective and long working relationship with our client.
Kevin McCormack, Director of Business Development at Starfish Construction.
