Boughton Biodiverse Green Roof Substrate

The greater amount of sand particles in this substrate allows it to hold onto a greater volume of water compared to EX1, but still allow rapid drainage when required. Due to the greater sand content, this substrate is not suitable for very lightweight applications and is more suited for green roofs which are designed to support a more in-depth plant community such as wildflower meadows or intentionally sporadic biodiverse planting.

Designed specifically for semi-intensive green roofs, this substrate should be installed at a depth of 120–180 mm. It is perfectly suited for biodiverse roofs, which require substrate to be installed at varied depths across the structure in order to increase variability. 

Due to its relatively free draining nature, temporary irrigation may be required to assist plant establishment. However, permanent irrigation systems are generally not installed on semi-intensive roofs as this will cause excessive plant growth and encourage weed development in the long term.

Features and benefits:

• Substrate density:
• Bulk density when oven dried: 0.99 g/cm³.
• Bulk density at 10% VMC: 1.08 g/cm³.
• Bulk density at field capacity: 1.4 g/cm³.
• Particle density: 1.38 g/cm³.
• Water and air:
• Field capacity: 40.0% v/v.
• Total porosity: 71.9%.
• Porosity at field capacity: 39.5%.
• Effective porosity: 32.3%.
• Saturated hydraulic conductivity: 151 mm/min.
• Chemical:
• Organic matter: 3.7%.
• pH value: 8.2.
• EC: 2.8 mS/cm.
• Plant available nutrients:
• Nitrogen: 12.3 mg/L.
• Phosphate: >165 mg/L.
• Potassium: >241 mg/L.
• Particle size distribution:
• Stones (>8 mm): 1.7%.
• Coarse gravel (8–4 mm): 16%.
• Fine gravel (4–2 mm): 2.6%.
• Very coarse sand (2–1 mm): 7.4%.
• Coarse sand (1.0–0.5 mm): 21.0%.
• Medium sand (0.5–0.25 mm): 33.9%.
• Fine sand (0.250–0.125 mm): 13.2%.
• Very fine sand (0.125–0.050 mm): 0.6%.
• Silt (0.050–0.002 mm): 2.3%.
• Clay (<0.002 mm): 1.4%.