Green Roof Drainage Board
The drainage board sits between the protection fleece and the filter fleece and does two jobs at once. Cuspated (or dimpled) HDPE cups hold a reservoir of rainwater for the vegetation to draw on between dry spells, while the gaps between cups carry surplus water across the roof to the outlets. We supply 25 mm and 40 mm cuspated drainage boards for nationwide pallet delivery, sized to suit the substrate depth and rainfall design of every extensive build-up.
HDPE cuspated drainage boards for green roofs. 25 mm and 40 mm profiles with water reservoir cups. Trade and DIY supply nationwide on pallet courier.
Frequently asked questions
What does a drainage board do on a green roof?
The drainage board holds a small reservoir of water for the vegetation to draw on between rainfall events, while moving surplus water across the roof to the outlets. Without it the substrate either dries out in summer or waterlogs in winter.
What depth of drainage board do I need?
25 mm cuspated drainage suits most extensive sedum roofs up to 80 mm substrate. 40 mm is used for biodiverse build-ups with 100 mm plus substrate, deep roofs, or longer drainage runs where more reservoir and faster flow are needed.
Is HDPE drainage board recyclable?
Yes. Our drainage boards are manufactured from recycled HDPE and are themselves recyclable at the end of the roof's service life.
About The Green Roofer
The Green Roofer designs, supplies and installs green roofs for homes, developers and commercial buildings across the UK, with strong coverage in Essex, Southend-on-Sea, Chelmsford and London. We work on everything from a single garden shed or extension to large commercial flat roofs. See our residential green roof services or our commercial roofing services.
Our systems include sedum roofs, biodiverse and wildflower roofs, intensive roof gardens, blue roofs for stormwater attenuation and bio-solar roofs that combine planting with solar panels. Smaller projects are welcome too, including a green roof for your shed. We also supply green roof materials UK-wide for trade customers and DIY projects: complete systems such as the certified sedum green roof system, traditional green roof system, biodiverse green roof system and lightweight biodiverse system, plus individual components including sedum mats, wildflower mats, green roof substrate, drainage board, filter fleece, protection fleece and decorative cobbles.
Every project starts with a free site survey and a clear, no-obligation quote. We check roof structure, load capacity, waterproofing and drainage before recommending a system, and we offer ongoing green roof maintenance so the planting stays healthy year after year. Green roofs help manage rainwater, improve insulation, extend the life of the waterproofing beneath them and support biodiversity, including Biodiversity Net Gain requirements on new developments.
Planning a project? Read our guide to green roof planning permission. For commercial buildings we also supply and fit rainwater hoppers and roof flashings and trims.
Call 01702 964002 or email hello@thegreenroofer.co.uk for a free, no-obligation quote.