Single-ply membrane
Single-ply membrane has become one of the most widely specified flat roof waterproofing systems in the UK, favoured for its speed of installation, lightweight profile, and long-term weather resistance. Available in a range of materials — including TPO, PVC, and EPDM — single-ply systems are highly versatile, suited to large commercial roofs, complex geometries, and projects where minimising load on the structure is a priority.
The performance of any single-ply installation, however, depends on more than the membrane alone. The insulation beneath it plays a critical role in determining the roof's thermal efficiency, structural stability, and the long-term integrity of the waterproofing layer above. Gradient's PIR insulation boards are designed to meet the specific demands of single-ply build-ups, supporting reliable installation across both mechanically fixed and fully adhered systems
Insulation requirements for single-ply systems
Single-ply membranes are thin by nature, which means any irregularity or weakness in the insulation substrate is more likely to be reflected in — or to compromise — the membrane above. Boards must offer a consistent, flat surface with sufficient compressive strength to resist the point loads imposed by mechanical fixings, foot traffic, and ballast where applicable.
In mechanically fixed systems, the insulation must also resist wind uplift forces transferred through the fixings, making compressive strength and pull-through resistance key specification criteria. In fully adhered systems, surface uniformity is paramount: any variation in the board surface can result in uneven adhesive coverage and weak bond lines in the membrane.
Key benefits of Gradient insulation for single-ply membrane
High compressive strength — Gradient PIR boards offer compressive strength of ≥150 kPa, providing the firm, stable base that single-ply systems require under both mechanical fixings and pedestrian traffic.
Flat, consistent surface — Precise manufacturing tolerances ensure even board surfaces across the entire roof area, supporting uniform adhesive coverage in bonded systems and reducing membrane stress at joints.
Dimensional stability — Minimal movement under thermal cycling keeps the membrane free from stress concentrations, reducing the risk of splitting or pull-away at laps and details.
Compatible with mechanically fixed and bonded build-ups — Gradient boards are suitable for use with both principal installation methods used in single-ply roofing, giving specifiers flexibility across different project types.
Tapered insulation options — Gradient's bespoke tapered insulation service allows drainage falls to be incorporated directly into the insulation layer, working in harmony with the membrane above to deliver effective, long-term roof drainage.
Suitable products for application:
Gradient's Eurothane Eurodeck is specifically engineered for use with mechanically fixed single-ply systems, offering a compressive strength of >150 kPa and the dimensional stability required for demanding commercial applications. Its robust facers and consistent thickness make it a trusted choice for large-format roofing projects.
For fully adhered systems, Powerdeck F provides the flat, stable substrate and strong compressive performance that bonded single-ply installations demand.
Deck-VQ
With a thermal performance of the core of lambda 0.006, it's the ideal solution for your renovation or new build projects with ease. Deck-VQ® offers long-term performance whilst maintaining the...
Eurothane Eurodeck
Eurothane® Eurodeck is compatible with mechanically fixed single-ply systems, benefiting from a compressive strength of >150 kPa as noted in our Technical Datasheet and dimensional stability that...
Plylok
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Powerdeck F
Powerdeck® F is compatible with multiple waterproofing systems, benefiting from a compressive strength of >150 kPa and dimensional stability. This ensures the flat surface finish required for...