Green roofs can be built in two different ways. Built-in-place green roofs involve installing a growing medium and vegetation directly on the roof surface. This approach allows for more customization and flexibility in terms of the shape, size, and vegetation, but it takes more time and money to install. These types of roofs are better for larger and more complex structures where a specific plant selection or design is important.
Modular green roofs are pre-made panels put together on the roof. They are faster and easier to install, can save money, and are a better fit for buildings with limited access to the roof. However, it may be more limited in terms of customization options, and may not be suitable for large roofs with complex shapes or slopes.