Off-membrane blue roof systems are being recognised as a vital part of the UK’s sustainable future, but what does true integration mean for designers, specifiers and contractors❓
With ACO’s method, off-membrane storage integration means modular tanks positioned above the roof build-up keep rainwater storage separate from the waterproofing layer, protecting the membrane while enabling controlled irrigation, hard landscaping and biosolar interfaces 💧
Keeping the storage away from the waterproof layer stops the repeated wetting and drying that concentrates moisture at joints and roof openings. Reducing that strain on the waterproofing helps preserve manufacturer warranties and avoids the extensive work a membrane replacement would otherwise require on multi-use roofs 👷
For inverted and hard-landscaped roofs, keeping stored water off the insulation also removes the need for heavy ballast and the risk of insulation lifting 👍
Passive irrigation using wicking mats connected to the stored water delivers moisture to planting soil and planters in paved areas without surface ponding or mechanical sprinklers. The result is reliable plant establishment, biosolar edge planting and lower energy and maintenance needs — crucial where access and solar-panel maintenance corridors must be kept clear 🌞
Early, joined-up design is essential: consider tank locations, wicking layout and outlet positions during concept stages to meet the London Plan Urban Greening Factor and avoid late-stage structural clashes. ACO’s method works with wicking networks and PV layouts, offers simpler installation than ballast systems, and delivers predictable weights on the roof, making multifunctional roofscapes coherent, maintainable and compliant ✅
Explore blue roofs in greater detail with our free guide, available here ⬇️