Overview
Lightweight sedum layer over a water-retention base; optionally add a smart valve to pre-drain before storms.
Medium€€≈60–100 L/m²Structural check required
Materials
- Root barrier membrane
- Drainage/retention panels + filter fleece
- Extensive green roof substrate (≈60–80 mm)
- Sedum mats or plugs
- Edge profiles and gravel border
- Optional: smart drain valve + controller
Tools
- Measuring tape, utility knife, shears
- Broom, wheelbarrow/buckets
- Sealant compatible with roofing membrane
- Fall arrest PPE if roof edge unprotected
Safety & Risks
- Work with fall protection; never alone.
- Protect waterproofing from punctures at all times.
- Do not block roof drains/overflows.
Maintenance
- Irrigate during establishment; weed quarterly.
- Fertilise annually per supplier guidance.
- Test smart valve and overflows seasonally.
Permits / Notes
- Building or fire safety rules may apply; consult local code and insurer.
- VvE/HOA approval for shared roofs.
Steps
- Obtain a structural assessment for load (wet weight).
- Clean roof, fix defects; lay root barrier with sealed overlaps.
- Install drainage/retention panels; cover with filter fleece.
- Install edge profiles; add gravel border for firebreak and drainage.
- Spread substrate evenly; hydrate.
- Lay sedum mats (or plant plugs); water thoroughly.
- Optional: install smart valve and connect to controller/weather pre-drain logic.