Extensive

Extensive Green Roof are designed to be low maintenance and lightweight, they require only a shallow layer of substrate (typically 6 to 10 cm) for the vegetation layer to grow in. Once established the vegetation such as sedums, grasses and herbs will require no permanent irrigation, although initial watering is needed. The vegetation will require minimum or no maintenance so access to the roof is not necessary. Extensive roofs are easier and less costly to install than an Intensive roof Garden.

Technical Details

Sedum

Growing in a strong coconut fibre mat Sedum Mats are supplied as a pre-grown instant vegetation layer. It is sown with an exceptional blend of ten to twelve stunning sedum plants to provide extended interest and colour throughout the flowering period.

Matting Depth: 25mm

Matting Size: 1.2m x 1m

Required Substrate Depth: 50mm

Required Drainage Layer: Roofdrain 20

Total System Depth: 97mm

Total Saturated Weight: 82.5kg per m2

Wildflower

A mixture of wildflowers, herbs and flowering perennials sustainably grown in the UK. Attractive to pollinators, it provides a biodiverse and colourful range that will flourish in the conditions created on many types of green roofs.

Matting Depth: 25mm

Matting Size: 1.2m x 1m

Required Substrate Depth: 75mm

Required Drainage Layer: Roofdrain 20

Total System Depth: 122mm

Total Saturated Weight: 107.5kg per m2

Grass

The mat comprises of an established mixture of slow growing and drought tolerant grasses with low maintenance requirements, growing in a felt mat. Left unmown, the turf will flower in late May to early June producing decorative seed heads.

Matting Depth: 25mm

Matting Size: 1.64 x 0.62

Required Substrate Depth: 100mm

Required Drainage Layer: Roofdrain 20

Total System Depth: 147mm

Total Saturated Weight: 132.5kg per m2

Substrate

Our substrate is a blend of lightweight manufactured topsoil and lightweight aggregate.

The topsoil is manufactured from reclaimed sand and PAS 100 green waste compost and is certified to BS3882:2015 standards. The specially matured and graded recycled green waste compost provides optimal stability and minimal leaching for organic matter and nutrients. The topsoil is blended with carefully selected and graded lightweight expanded clay aggregate, sourced from the UK.

Our substrate provides good aeration and water holding properties and controlled fertility levels. It is simple to work with, lightweight, and offers guaranteed consistency throughout the green roof installation.

Roofdrain 20

Our drainage layer, Roofdrain 20, is ideal for extensive green roofs as it provides a lightweight drainage layer with a water reservoir to sustain plant growth. Roofdrain attenuates rainfall making it an important element of SUDS system. Roofdrain consists of a perforated cuspated recycled HDPE (high density polyethylene) core with selected geotextiles thermally bonded on each side.

The core acts as a water reservoir holding 4.5-5.5 litres per square metre for plants to access in dry periods. The core is perforated to allow excess rainwater to flow into the underside and away to drainage outlets. The upper geotextile also has a ‘zero’ breakthrough head to prevent over-saturation of the substrate. The lower geotextile has two key functions: it offers additional protection to the waterproof membrane and acts as an extra moisture retentive layer, holding an additional 1.0 litres per square metre.

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