A green roof installer designs and installs living roof systems on flat or low-pitch roofs. Extensive systems use shallow substrate (60-150mm) planted with drought-tolerant sedum, mosses or wildflowers and require minimal maintenance. Intensive systems use deeper substrate (150mm+) supporting grasses, perennials or even shrubs and need regular maintenance. Both types provide thermal insulation, reduce surface water runoff (SuDS benefit), extend waterproofing membrane life and provide biodiversity net gain habitat credits under the 2024 BNG mandatory requirement.
What they do
- Structural load assessment - green roofs add 60-200kg/m2 when wet
- Waterproofing membrane inspection or installation
- Root barrier and drainage layer installation
- Filter fleece and growing substrate specification and laying
- Planting - sedum mat, wildflower plug or biodiverse brownfield mix
- Irrigation system installation (intensive roofs)
- Edge restraints, parapets and access route detailing
- Maintenance plan and BNG habitat management agreement
When you need one
A green roof installer is needed when you want a living roof on a flat or shallow-pitch surface, need to meet Biodiversity Net Gain requirements or want to manage surface water runoff.
Typical costs (UK, 2025)
| System type | Typical cost per m2 |
|---|---|
| Extensive sedum mat (pre-grown, 60-100mm substrate) | £50 - £90/m2 |
| Extensive wildflower or biodiverse mix (plug planted) | £80 - £130/m2 |
| Semi-intensive mixed planting (100-200mm substrate) | £120 - £200/m2 |
| Intensive amenity roof (200mm+ substrate, perennials) | £180 - £300/m2 |
| Waterproofing membrane if replacement required | £40 - £80/m2 extra |
| Annual maintenance visit (weeding, fertilising) | £3 - £6/m2 |
Minimum area for most installers is 20-50m2. Structural survey and membrane inspection are additional costs to factor in.
Qualifications to look for
The GRO publishes the Green Roof Code of Best Practice for the UK. Members commit to following these standards. Check membership at greenrooforganisation.co.uk.
Chartered Landscape Architects are often involved in the design of biodiverse green roofs where BNG habitat credits and management plans are required.
Major system manufacturers (ZinCo, Bauder, Alumasc, Icopal) offer installer training. Using a certified installer maintains the system warranty and ensures correct substrate and drainage layer specification.
How to find a reputable green roof installer
Frequently asked questions
Do I need planning permission for a green roof?
A sedum or wildflower green roof on a flat roof extension is usually permitted development, provided the roof does not project above the existing roofline. Green roofs on listed buildings, in conservation areas, or that change the height or appearance significantly may need consent. Always check with your local planning authority if in doubt.
How long does a green roof last?
A correctly installed green roof with a quality waterproofing membrane typically lasts 40-60 years - significantly longer than a conventional flat roof (15-25 years). The vegetation layer protects the membrane from UV degradation and temperature extremes. Annual maintenance keeps the system performing correctly.
Can a green roof contribute to Biodiversity Net Gain?
Yes. Under the mandatory BNG requirements introduced in 2024, a well-designed biodiverse green roof (wildflower, brownfield or plug-planted) counts as a habitat unit in the statutory metric. Sedum mats score lower than biodiverse roofs. A green roof specialist or ecologist should advise on the habitat type and management plan needed to maximise the BNG score.