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INTENSIVE ROOFS – MIXED PLANTING AND TURF
Intensive green roofs are built to feel like a real garden, similar to what you’d see at ground level. They can include plants like grasses, flowers, shrubs, bulbs and, in some cases, small trees – such as the roof at the Stella McCartney store in central London.
Because these plants are larger and heavier, intensive roofs need a strong roof structure, a deep growing layer of at least 200mm, and regular irrigation, feeding, and maintenance.
Turf roofs are also classed as intensive roofs, as they need high levels of water, nutrients, and ongoing care.
Many intensive roofs are designed as usable spaces, with features like paving, lawns, and planters. When combined with biosolar systems, these roofs can support plant life and generate renewable energy, making them a powerful option for sustainable buildings.
SEMI-INTENSIVE ROOF
Semi-intensive green roofs sit between extensive and intensive systems. They use plants that need less care than intensive roofs, such as wildflowers, perennials (including herbs like those shown on this City of London roof), grasses, bulbs, and small shrubs.
Wildflower meadow roofs are a common example of a semi-intensive system.
These roofs are heavier than extensive roofs, but lighter than intensive roofs, making them a good middle-ground option.
Plants on semi-intensive roofs need a growing layer between 100mm and 200mm, along with more irrigation, feeding, and maintenance than a typical sedum or extensive roof.
When paired with biosolar systems, semi-intensive roofs allow space for healthy plant growth while still supporting solar panels, helping buildings boost biodiversity and produce clean energy at the same time.
EXTENSIVE ROOF
Extensive green roofs are designed to be low maintenance and mostly look after themselves. They use low-growing plants that can handle cold weather and long dry periods, such as mosses, succulents, herbs, grasses, and some bulbs.
The most common plants used on extensive roofs are sedums, like the ones shown on the roofs pictured.
Studies of the oldest green roofs show that sedum is one of the longest-lasting and most reliable plant types for roof environments.
Extensive roofs are especially well suited to biosolar systems, as sedum grows well around solar panels, needs very little care, and helps improve panel performance while supporting biodiversity.
BIODIVERSE GREEN ROOF
Biodiverse green roofs are designed to recreate natural habitats and support local wildlife. They use a wide mix of native plants, wildflowers, grasses, and varied substrates to encourage insects, birds, and pollinators to thrive.
These roofs are built to mimic natural ground conditions, often including features like logs, stones, sand areas, and varied soil depths to increase habitat value.
Biodiverse roofs can vary in weight depending on design, but they are typically planned around ecological goals rather than just appearance. This makes them ideal for developments that need to meet biodiversity net gain or planning requirements.
Growing depths usually range from 80mm to over 200mm depending on the habitat being created. Maintenance is generally low but focused on protecting the ecological balance rather than keeping a neat “garden” look.
When combined with solar systems, biodiverse roofs create a powerful dual-purpose solution — generating clean energy while actively improving biodiversity and supporting long-term environmental resilience.
BLUE ROOF
Blue roofs are designed to manage and control rainwater at roof level. Instead of immediately draining water away, they temporarily store it and release it slowly to reduce pressure on drainage systems.
These roofs are especially useful in urban areas where heavy rainfall can overwhelm sewers and cause flooding. By holding water back, blue roofs help manage stormwater more effectively.
Blue roofs can be installed on flat or low-pitched buildings and are often integrated beneath green roof systems to provide both water management and environmental benefits.
They require careful structural design to handle the weight of stored water and must include flow control systems to regulate discharge rates.
When paired with solar panels or green roofs, blue roofs become part of a smart, multi-functional roofing system — supporting flood prevention, improving sustainability, and helping buildings adapt to changing weather patterns.
BROWN ROOF
Brown roofs are designed to recreate the natural conditions of previously developed land, supporting local and often rare species. They typically use recycled materials such as crushed concrete, rubble, and subsoil to form a varied, low-nutrient growing medium that encourages native plants and invertebrates to colonise naturally.
These roofs are built to mimic brownfield habitats, often including features like stones, logs, sand patches, and uneven surfaces to provide shelter and nesting opportunities for insects and birds. Rather than being planted for appearance, brown roofs are left to develop over time, creating a more authentic and resilient ecosystem.
Brown roofs can vary in depth and weight depending on the design, but are usually planned around ecological targets rather than aesthetics. This makes them particularly valuable for developments needing to meet biodiversity net gain requirements or replace habitats lost during construction.
Maintenance is generally minimal, focusing on preserving habitat conditions rather than managing plant growth. Over time, vegetation will establish naturally, resulting in a unique and ever-changing roof landscape.
When combined with solar systems, brown roofs form a highly effective biosolar solution — supporting biodiversity while generating renewable energy, and helping buildings deliver long-term environmental value.
WHERE TO GO NEXT
To understand how biosolar compares with other combined roof systems, continue to Biosolar vs Green Roof Solar.
If you’d like to explore what a biosolar roof can achieve in terms of energy performance, biodiversity value, and planning outcomes, visit Key Benefits.
For policy drivers and regulatory context, the Biosolar and Planning / Policy page provides a concise overview of current UK guidance.
If you’re seeking a specialist contractor to deliver a biosolar roof system visit PV Plus
