Blue Roofs
Overview
Blue roofs provide an engineered rainwater attenuation solution for inverted roofs and conventional warm roofs. They can help designers to meet requirements for sustainable urban drainage systems (SUDS). A blue roof system does not store water, but is designed to hold a certain capacity of water (based on the expected severity of storm events) and discharge it over a 24-hour period.
In the case of inverted flat roofs, systems are compatible with typical ballast solutions, including gravel, paving slabs and green roof elements. Extruded polystyrene (XPS) therefore remains the preferred insulation option.
How do blue roof systems perform?
At Polyfoam XPS, we work closely with leading blue roof manufacturers to ensure we understand how their systems work.
The void formers that create the water attenuation zone are generally designed to provide self-contained, temporary storage sufficient to cope with a 1 in 100-year storm. They do not rely on the inverted roof build-up (insulation and water flow reducing layer, such as Slimline Zero Membrane) to provide extra drainage capacity.
The flat roofing industry is still refining guidance on the use of, and best practice associated with, blue roofs, which remain a relatively new approach. Advice is available from industry bodies about correct design and specification, and that advice is reviewed and updated on an ongoing basis.
Product Benefits
- 15mm lap joint.
- Excellent thermal performance.
- High compressive strength.
- Highly resistant to water absorption.
- Able to resist repeated freeze/thaw cycles.
- Lightweight and easy to install.
- Tough and durable, not easily damaged.
- Dimensionally stable.
- Thermal performance of an inverted roof is improved when used in conjunction with Polyfoam Slimline Zero Membrane.
- Environmental product declaration (EPD).
- BES 6001: Responsible Sourcing of Construction Products.
- ISO 9001, 14001, 45001 and 50001 management systems.
What Polyfoam XPS products are suitable for a blue roof?
Polyfoam XPS Ltd is a leading manufacturer of closed cell, extruded polystyrene insulation. The Polyfoam range is lightweight, strong, moisture resistant and easy to cut and shape, providing thermal performance and strength for the lifetime of the building.
An important part of flat roof design is the detailing and construction of suitable upstands around the roof edge, and Polyfoam Upstand Board limits heat loss due to thermal bridging at the junction of the flat roof with the external wall.
Polyfoam Roofboard Extra provides all the necessary performance characteristics to achieve a durable, high performance inverted roof construction in any UK location.