Plan a green roof that suits the building
A green roof can provide habitat and retain some rainfall. Long-term performance depends on coordinating plants, roof construction and maintenance. Start with what you want the roof to do and what the existing structure can support.
Extensive, intensive or combined with solar?
The type of green roof determines more than plant height. It affects weight, construction, water needs and use. A roof needing limited care is not automatically a roof garden suitable for people to spend time on.
| Option | What matters |
|---|---|
| Extensive planting | Low vegetation adapted to roof conditions, primarily for greening rather than regular recreational access. |
| Intensive roof garden | Perennials, shrubs or usable areas, with greater demands on structure, care and safe access. |
| Biosolar roof | Plan vegetation and panels together, including plant height, shading, water and maintenance routes. |
| Improving an existing roof | Assess vegetation and layers, then establish why areas have failed before adding material. |
What needs checking before installation?
On an existing roof, the initial assessment includes structure, waterproofing, junctions and drainage. The saturated weight matters alongside other loads and roof installations. A product weight in a brochure is not a structural assessment of your building.
Establish whether the waterproofing is suitable and has adequate resistance or protection against roots. Avoid investing in planting over a membrane likely to need replacement soon. If there are leaks, investigate their cause first.
Each part of the build-up has a purpose
Protection, water storage, drainage, filtration and the growing layer must work as a system. Ordinary garden soil is not an interchangeable substitute. Suitable materials and depths depend on the roof, planting goals and local requirements.
Outlets, inspection points, junctions and necessary clear perimeter areas must remain accessible. Sloping roofs may need particular measures against slipping and erosion. Even a small garage roof requires a suitable construction system.
Choose plants for the site and purpose
Sun, shade, wind and available growing depth influence what will thrive. Site-adapted low vegetation suits many extensive roofs. Ecological value does not come simply from ordering the greatest number of species.
Seed, young plants and pre-grown mats differ in initial appearance, labour and establishment. Mats give cover quickly but still need to root. Seeding requires time and suitable weather. Agree who provides establishment care and any necessary remedial planting.
Coordinate planting and solar panels
Plants and panels can share a roof when the layout serves both. Vegetation must not continually shade the modules, while the modules themselves alter light and water distribution.
Coordinate greening, solar installation and roofing work early. Additional loads, panel height, access and responsibility for vegetation between and beneath panels need agreement. Panels added later should not block previously planned maintenance routes.
Compare green roof costs on the same basis
Compare the actual planted area and equivalent work. A materials-only price does not necessarily include roof assessment, lifting materials, labour, fall protection or waterproofing repairs.
In October 2026, one sedum materials kit was advertised at around CHF 63/m² including tax. Delivery, installation, protection layer and perimeter gravel were extra. This is a materials example, not a completed-roof price.
Small roofs can cost more per square metre because access and site setup still have to be arranged. Separate greening, preparatory roofing work and ongoing care in the quote. Local grants have their own conditions, which should be checked before placing an order.
- Area and construction. Which net area, layers, vegetation and perimeter details are included?
- Site and delivery. Does the price cover lifting, protection, travel and waste removal?
- Handover and care. Who checks establishment, and what follow-up work is agreed?
Access and responsibilities belong in the quote
Building height and existing roof access affect material handling. Describe the current situation; the contractor determines a safe working method. Do not climb onto an unprotected roof to take measurements for your enquiry.
Check local requirements and agree who coordinates roofing, vegetation and any solar installation. A rule in one municipality is not automatically a requirement throughout Switzerland.
Low maintenance does not mean no maintenance
Extensive roofs still need checks. Unwanted woody growth, problem plants, blocked outlets and shaded solar panels need to be spotted early. Plant care and technical roof maintenance are distinct tasks, so responsibilities should be clear.
Inspection frequency, watering and nutrition depend on the system, establishment stage and location. A newly planted roof may need different care from established vegetation. Permanent irrigation or routine fertilising is not appropriate for every extensive roof.
Frequently asked questions
Can any flat roof be planted?
No. Load capacity, waterproofing condition and suitability, drainage and intended use must be compatible. Have these checked on an existing building before ordering materials.
Can a sloping roof be greened?
In some cases, with a suitable system. Pitch, resistance to sliding and erosion, and safe installation require specific planning.
Do I need to choose the layers and growing depth myself?
No. Your goal, known area and existing roof condition are enough for an initial enquiry. The appropriate build-up is established during technical design.
Can I renew just the existing vegetation?
Yes, for example where there are bare patches, unwanted plants or a change of use. If drainage or waterproofing is faulty, adding growing material alone is not enough.
Are green roofs compatible with solar panels?
Yes, when both systems are coordinated. Plant height, loads, water distribution and room for maintenance are particularly important.
