Responsible rainwater management for flat roofs
A blue roof is a flat roofing system specifically designed to temporarily store rainwater and release it in a controlled manner.
Single ply waterproofing of blue roof systems
Unlike traditional drainage systems that immediately channel water away, blue roofs help mitigate flood risk by easing the burden on urban drainage infrastructure during heavy rainfall events. The system is composed of multiple technical layers that:
- Retain rainwater on the roof surface for a defined period.
- Discharge water gradually through flow-restricting outlets or control devices.
- Prevent stormwater surges that can overwhelm drainage networks.
Blue roofs can be installed on new buildings or retrofitted to existing flat roofs and are fully compatible with green roofs or biosolar systems.
RENOLIT ALKORPLAN Classic
Cost-effective synthetic single ply membrane of plasticised PVC-P.
See product
Adhered system
| For concrete support. |
| For when the vapour control layer cannot be perforated. |
| Compatible with old bituminous membrane. |
Benefits of choosing our blue roof system for your project
Reduction water flooding
Supports SUDs
Combination with Green Roofs
Improved insulation
Most used accessories for the installation of this product
RENOLIT ALKORPLAN Blue roof FAQs
Because it not only protects your building but also plays a vital role in urban climate adaptation. Blue Roof is a forward-thinking investment in sustainability, efficiency, and environmental responsibility.
Blue Roof is designed to temporarily store rainwater on the roof surface and release it gradually through flow-restricting outlets. In contrast, traditional systems aim to discharge water immediately. This controlled release helps prevent localised flooding and reduces pressure on urban drainage infrastructure.
Yes, Blue Roofs can be retrofitted to existing flat roofs, provided the structure can support the temporary water load. A structural assessment is recommended to ensure compliance with building regulations and safety standards.
Yes, Blue Roofs can be integrated with green roofs (creating a Blue-Green Roof) or with biosolar systems, offering a multifunctional solution that combines stormwater management, biodiversity, and renewable energy generation.
Blue Roofs are ideal for:
- Urban developments with limited green space.
- Commercial and public buildings such as schools, hospitals, and offices.
- Residential blocks in flood-prone areas. They are particularly valuable in SuDS-compliant projects and developments seeking BREEAM or LEED certification.
The retention capacity depends on the design specification, but typical systems can hold 20–100 litres per square metre. The exact volume is calculated based on rainfall intensity, roof area, and discharge rate requirements.
