Thin-layer green roofs with MDP

This is our concept for thin-layer green roofs in dense cities like Hong Kong. Most green roofs need deep soil, heavy drainage layers and a stronger structure, which rules out many existing buildings. It keeps the planted layer shallow and light, and uses MDP to drain it.

Why thin-layer

A shallow bed of hardy sedums and grasses weighs far less than a roof garden, so it can suit roofs that were never designed to carry one. Once established it needs little upkeep and little or no watering.

What MDP adds

MDP drains the planted layer steadily without clogging, so the roof doesn't waterlog and roots stay healthy. Instead of running straight to the downpipes, excess rain is collected, and can be stored and reused for irrigation or flushing.

The benefits

• Cooler roofs and top floors in summer
• Less stormwater runoff in heavy rain
• Rainwater collected for reuse
• More green space and habitat in the city
• Lighter than a conventional green roof

The green roof is at the concept stage. The images on this page are AI-generated concept visuals.