Standardising success: How Onduline’s ISOLINE LOW LINE is supporting Aldi’s nationwide re-roofing programme
12 August 2025When Aldi decided to centralise its approach to roof refurbishments, it marked a significant change in the way the supermarket chain manages its growing property estate. Previously, re-roofing had been handled on a store-by-store basis, resulting in mixed materials, varying specifications and inconsistent performance across the UK. Aldi sought a standardised specification that would deliver consistent quality, reliability and visual appeal across its national portfolio.
To make this happen, Aldi turned to its appointed design team, including The Harris Partnership as architects and Edge as quantity surveyors, both of whom have extensive experience supporting the brand’s refurbishment and new-build programmes. A collaborative design meeting was held to explore the most effective approach to roof replacement across the estate, with input from key stakeholders helping to shape a robust and repeatable specification for future refurbishments.
Aiden Salmons - Senior Costs Manager at Edge
“Aldi needed a solution that would provide consistent performance and appearance across all sites, but also one that could adapt to the practical realities of refurbishing existing buildings,” explains Aiden Salmons, Senior Costs Manager at Edge.
“That meant accommodating a variety of roof types and conditions, from long rafter spans and ageing materials to ensuring the stores could stay open while the work was carried out. The specification had to be flexible, reliable, and robust enough to meet all of those demands.”
ISOLINE LOW LINE
During initial discussions between specifiers, architects and contractors, Burton Roofing introduced Onduline’s ISOLINE® LOW LINE as a potential solution. While already recognised for its ability to support waterproofing at pitches as low as 10 degrees, ISOLINE® LOW LINE offered much more than just a pitch-based advantage.
As a sub-roof system, it provided a secondary waterproofing layer that could accommodate a range of technical challenges, making it particularly suitable for re-roofing schemes where existing tiles needed to be reused or where long rafter lengths created vulnerability to water ingress.
Aldi integration
With these benefits in mind, ISOLINE® LOW LINE was integrated into the proposed specification and trialled at three Aldi stores, Gainsborough, Barnsley, and Shirebrook. These pilot sites allowed the project team to assess the system’s performance in real-world conditions. Following overwhelmingly positive results, Aldi approved the ISOLINE-based specification for full-scale national rollout.
Since the first trials, 16 re-roofing projects have now been completed using the specification, with further schemes in the pipeline. The feedback from site teams and delivery partners has been consistently positive.
“One of the major advantages of ISOLINE is its ability to keep the roof watertight independently of the tiles,” adds Aiden. “This means stores can stay open throughout the works while keeping noise, dust and other disturbances to a minimum, which is critical for retail clients. It also creates a safer environment for contractors and customers alike, as the risk of falling debris is reduced while work is in progress.”
Northstone Materials
A key element of the programme’s success has been the collaboration between Onduline and Northstone Tiles. Previously, Northstone’s tiles weren’t suitable for use on Aldi’s roofs due to pitch and waterproofing constraints.
However, by integrating ISOLINE® LOW LINE into the specification, Aldi was able to retain the aesthetic and performance benefits of Northstone’s UK-manufactured tiles, even on stores with challenging roof designs. This has helped ensure consistency across the retailer’s estate while maintaining installation efficiency for delivery teams.
Ken Anderson - National Sales Manager at Northstone
“Working with Onduline has enabled us to meet Aldi’s brief with confidence,” says Ken Anderson, National Sales Manager at Northstone Tiles.
“Thanks to the ISOLINE® LOW LINE system acting as the primary waterproofing layer, we’ve been able to supply our tiles to multiple Aldi stores, overcoming pitch and waterproofing issues that would otherwise have made this impossible. It’s helped deliver a durable, watertight, and visually consistent result that supports the goals of the wider re-roofing programme."
Alongside its technical performance, ISOLINE® LOW LINE has also been praised for its ease of installation, with contractors noting how the lightweight panels and familiar fixing method help speed up project delivery. Onduline’s technical team has remained actively involved throughout, providing site support, training and guidance to ensure the system is applied correctly and consistently.
Paul Duffy - Managing Director at Onduline Building Products
For Paul Duffy, Managing Director at Onduline Building Products, the Aldi programme is a strong example of how sub-roof solutions are evolving to meet complex refurbishment needs.
“This programme is a great example of what can be achieved through early collaboration and shared ambition,” says Paul. “By working closely with Edge, Northstone Tiles, and the wider Aldi team, we’ve supported the development of a robust and adaptable roofing specification. The ISOLINE® LOW LINE system helps tackle modern-day challenges we’re seeing more often in refurbishment projects, whether it’s complex roof structures, tile reuse, or keeping buildings operational during works. It’s a privilege to see our system specified as part of such a prestigious and forward-thinking rollout.”
As Aldi continues to invest in the quality and consistency of its store environments, the ISOLINE® LOW LINE system remains central to a specification that balances performance, safety and business continuity, all while extending the lifecycle of one of the most critical elements of the building envelope.
Project Information
Companies involved in Aldi’s national re-roofing rollout programme:
| Architect: | The Harris Partnership |
| Project Management: | Edge Property and construction consultancy |
| Main Contractors: | |
| Sub-Contractors: | Martin Brooks Ltd Complete Roofing Systems Nationwide Specialist Services Ltd Jennings Roofing Ltd Lovetts Roofing Ltd Fosters Roofing Ltd |
| Building Merchant: | Burton Roofing Merchants Ltd |
| Product Manufacturers: | Onduline Building Products Northstone Materials |
Get In Touch
Do you often come across situations where the chosen tile for your project restricts your design and overall aesthetic due to pitch limitations?
ISOLINE LOW LINE is the solution.
- Any tile can be used on your project as low as 10 degrees
- Easy and fast installation
- Eco-responsible
- Cost-effective
- Guaranteed waterproofing
Get in touch today. Our team of experts are available to assist you, email: [email protected] or call 0207 727 0533.
RIBA CPD
Our RIBA accredited CPD is available to give architects and building professionals a greater understanding of the benefits low pitched roofs and sub-roof systems can offer.
‘Understanding low pitched roofs and the benefits of sub-roof systems’ is the latest addition to Onduline’s extensive training programme and provides an overview of the importance of roof pitches and how to ensure the right pitch for a building.
