Division C - Accepted Materials
Group - Vegetated Roof Systems
CGT Extensive Layered Vegetated Roof System
by Columbia Green Technologies LLC
| System/Material Acceptance and Product Details
The information published in the RCABC Roofing Practices Manual and offered below does NOT represent a complete set of the manufacturer’s data or specifications, nor is this system and its various materials recommended or endorsed by the Guarantor. The preparation of a detailed specification is the responsibility of the Design Authority.
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- Vegetated Roof System Manufacturer
- https://columbia-green.com/
- Accepted for the RoofStar Guarantee Program
- June 11, 2026
- Accepted for application in
- Vegetated Roof Systems
- Acceptance Criteria
- Refer to the RGC Standard for Vegetated Roofs
- System Summary
- The Columbia Green Technologies (CGT) Extensive Layered System is a lightweight built-up vegetated roof system that accommodates a variety of layouts. The system’s layers can be easily shaped to fit curves and angles.
- This system is designed by CGT to enhance stormwater management by capturing rainwater and irrigation, which can reduce or eliminating runoff. It is specifically engineered to promote healthy plant root development by ensuring adequate airflow throughout the system.
- Due to the limited depth of the growing media, Extensive Layered Systems are typically planted with low-growing sedum varieties well-suited for rooftop environments. Growing media depths are determined by structural considerations, plant selection, and stormwater retention objectives.
- Manufacturer online resources
- [link page name]
- System Type
- Extensive
- System Depth
- 110 mm (4.38") to 240 mm (9.38")
- Growing Media Depth
- 80 mm (3") to 200 mm (8")
- Vegetation Profile
- Sedum-Herbaceus-Grasses
- Suitable climate zones
- All BC zones, subject to manufacturer's approval
- System Components*
- In the usual order, from top to bottom; click on link for Technical Data Sheet (TDS)
- Roof Assembly by roofing Contractor
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- †Guarantor's Notes
- Systems labeled "Inverted" are designed for a protected membrane roof assembly, also known as an inverted roof assembly.
- While Semi-intensive and Intensive vegetated roof systems are limited to only protected membrane roofs (See the Sentence 1.1.3.2.(5) in the "RGC Standard for Vegetated Roofs"), some vegetated roof system manufacturers offer their systems for conventionally insulated roofs. To request a written Variance to the published limitation, follow the requirements in Article 1.1.3.6..
- *Conditions and Limitations
- Note that system thickness is dependent upon the selection of components, which is determined (in part) by design parameters, including hydrological requirements. Consult with the vegetated roof system manufacturer for options and saturated system weight.
- Also note that vegetation coverage under the RoofStar Vegetated Roof Guarantee applies only to extensive systems planted with mats or trays - see Part 3 of Division A for more about coverage.
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