What are our Top Five Tips for creating Biodiverse Green Roofs

1. Design

Design biodiversity in from inception, consider the weight loading of the roof, Biodiverse roofs or Brown roofs typically have an undulating depth of 80mm to 150mm (av 120mm), so they can weigh in at around 250kg per m2 fully saturated. So if you design the biodiverse roof in from the start of a build you can have a variety of options later down the line.  This allows developers to enhance green roofs throughout the seasons.

Guidance from the Green Roof Organisation guide of best practice states:

BIODIVERSE ROOFS

Light weight (typically less than 250kg per
m2 saturated density),
Low maintenance (1-3 visits per year),
Shallow substrates (up to 150mm),
Inclusion of natural features to support
insect and bird life,
Not designed for public access.

If you are considering a retrofit of a biodiverse roof, then it is essential to  check with a structural engineer to make sure the building can take the weight of your plans.

Use a range of plug plants from the London wildflower mix and wildflower seeds, then if it’s in the warmer months make sure to water it in so plants can get well established.

Horticultural variety is key to create rich biodiversity on green roofs.  Native hardy species will provide invaluable forage for birds, bugs and bees.

Try adding sand piles for solitary and mason bees, install bat and bird boxes as well as a range of log piles at various degrees of degradation to encourage invertebrates.

Many clients gravitate towards smart bug hotels when roofs are overlooked from other buildings and to optimise nesting for a variety of birds and insects.