Green roof & planters

Green roof

Last updated: 26 October 2026

Root-barrier waterproofing, Nophadrain drainage and FLL-compliant substrate: the system that ensures a green roof lasts 40 years instead of 10.

The system at a glance

Solutions & Applications · Green Flat Roof

A green roof is a long-term investment — and its lifespan is determined by layers which, once installed, are never touched again. The correct solution does not compromise on these layers: ESHAGUM ANTIROOT root-resistant waterproofing, high-performance composite drainage system Nophadrain and a carefully designed water drainage system, so that the green flat roof performs for decades, even in intensive planting schemes and accessible gardens.

Why a green roof?

Beyond its aesthetic appeal, a green roof acts as an additional layer of thermal insulation (reducing cooling and heating loads), retains rainwater, thereby relieving the pressure on the urban drainage system during storms, acts as a noise barrier, reduces the ‘urban heat island’ effect and protects the underlying insulation from thermal stress caused by the sun — thereby increasing its lifespan and the value of the property.

Why the ‘invisible’ layers make or break a project

The two main threats to a green flat roof are always the same: standing water and roots penetrating the waterproofing. Because flat roof refurbishment is costly and time-consuming, it is the quality of the ‘invisible’ layers that makes the difference between a solution that lasts 10 years and one that lasts 40+ years. That is where the real difference lies.

Layering, step by step

From the load-bearing structure to planting:

Anti-root waterproofing — ESHAGUM ANTIROOT B5: 2-in-1 bituminous membrane (waterproofing + strong anti-root action with Preventol B5 additive), polyester reinforcement, flexible down to −10 °C. A continuous barrier that prevents roots from reaching the slab for the entire lifetime of the system.
Protective membrane — EshaProtect (HDPE 1.0 mm): protects the root-resistant waterproofing from mechanical stress during construction and enhances the system’s root-resistant performance.
Drainage + filtration + protection (3-in-1) — Nophadrain ND 4+1h: composite drainage sheet with a 17 mm thick perforated HIPS core and PP geotextiles bonded on both sides. It combines filtration, drainage, water storage and protection in a single layer, with a water storage capacity of 4.3 l/m² (water-saving) and a compressive strength of 600 kPa (≈60 t/m²). Part of the EshaOxygen system.
Drainage system — GEODRAIN PLUS perimeter: a perforated pipe with integrated geotextile, which does not become blocked by silt.
Nutrient substrate — EshaOxygen GM planting substrate, in accordance with the FLL 2018 guidelines (controlled particle size distribution, pH 6.0–8.5, water-holding capacity, saturated bulk density ≤ 1,300 kg/m³). In intensive planting schemes, WSM-50 stone wool is added (water storage ≈40 kg/m² via capillary rise, plus a garden soil filter).
Planting: extensive (soil depth 7–20 cm, ~50 kg/m², gradients up to 30°) or intensive (soil depth >21 cm, ≥280 kg/m², shrubs, trees, walkable garden) — depending on the static load and intended use.

The slab gradients are set at >1.8 per cent to ensure proper drainage.

Thermal insulation: two perspectives

	Beneath the waterproofing — warm flat roof	Beyond waterproofing — inverted roof
Series	Slab → vapour barrier → FIBRANxps 300 → root-resistant waterproofing → rest of the system	Slab → root-resistant waterproofing → FIBRANxps 300 → drainage → rest of the system
Please note	The first layer on top of the XPS is applied to the insulation without the use of a flame — either self-adhesive or via a vapour pressure release layer	XPS performs reliably in a damp environment — which is why only XPS is used
Advantage	The vapour barrier protects the insulation from moisture within the building	The waterproofing remains at a constant temperature, protected by the insulation

Why Nophadrain: ‘the heart of the system’

Unlike gravel (unstable drainage capacity, heavy, minimum depth 100 mm, risk of damage to the waterproofing), Nophadrain composite sheets provide consistent, predictable drainage over time, with minimal weight (~1 kg/m²) and integrated filters. The choice of type is based on the planting and the gradients:

Type ND	Compressive strength	Water storage	Height	Main application
ND 4+1h	600 kPa (60 t/m²)	4.3 l/m²	17 mm	Extensive planting
ND 4+1	700 kPa (70 t/m²)	3.6 l/m²	13.5 mm	Intensive planting
ND 5+1	500 kPa (50 t/m²)	5.8 l/m²	27.5 mm	Elongation, shrinkage <1.8%
ND 200	700 kPa (70 t/m²)	—	12.5 mm	Extensive, sloping

The key advantages of ND technology: uniform wall thickness of cones (long-term compressive strength), an HIPS core instead of HDPE (guaranteed, long-term drainage capacity — HDPE ‘settles’ over time under load), uniformly bonded filters that do not become compressed in the voids, and recycled HIPS for sustainability. No memory effect, ready for immediate use.

ARGYNET Note

The most common fault with green flat roofs is not the waterproofing but the drainage system, which becomes blocked over time. The system resolves this with a dual-layer filtration system (the double-sided geotextiles of Nophadrain + the geotextile of GEODRAIN PLUS) — and the drainage network remains clear for decades, provided the inspection chambers are checked.

The choice between an extensive or intensive flat roof alters the static load and the substrate depth. For intensive planting and accessible roof gardens, the ND 4+1 with a compressive strength of 700 kPa provides the compressive strength reserve that simple drainage systems lack; the ND 4+1h, with greater water storage capacity, is the choice for extensive flat roofs.

At ARGYNET, we calculate loads and quantities for each project and specify the entire system — root-resistant waterproofing, drainage, water discharge, sub-base and planting.