Tag: greenroofs

Built-in-Place and Modular Vegetated Systems

Traditionally, vegetation has been established on roofs using plugs, cuttings or seeds. These are called built-in-place vegetated systems. The initial vegetation coverage typically ranges 5-15% and it takes regular TLC (water, weed and feed) and patience (1-3 years) for the young plants to mature and establish.

Increasingly, vegetation is first pre-grown in modules on the ground for quicker establishment on the roof. These are called modular vegetated systems. These pre-vegetated modules contain mature plants with 80+% vegetation coverage at delivery, and typically takes only one growing season to establish on the roof.

If we could use an analogy comparing establishing a green roof to starting a front lawn, built-in-place systems would be akin to sowing seeds. Modular systems would be equivalent to laying sod. Instant green, ease of installation, reduced establishment time and maintenance efforts are some attributes that make modular vegetated systems such as mats and trays popular in North America.

Modular Pre-Vegetated Mat and Tray Systems

Modular pre-vegetated green roof systems are similar to laying sod.

Pre-vegetated mats contain vegetation planted in a shallow growing medium (2-3 cm) on a vegetation carrier. Natural carriers made of coir fibre matting decompose over time and integrate into the media. Synthetic carriers consisting of 3D entangled mesh provide enhanced root anchorage and mat integrity, which are suited for sloped roofs. They are durable and can be readily rolled back, even many years later, for membrane access. Pre-vegetated mat systems are loose laid, yet highly wind resistant.

Pre-vegetated trays contain vegetation planted in containers resembling shallow planter boxes. They are made of plastics or metals and come in different sizes, typically containing 5–20 cm of growing medium. Some trays are designed to be fastened or interlocked together for stability and wind resistance. There are also trays that are made of natural materials that decompose and integrate into the media over time.

Green roof market share in North America by planting types according to GRHC, 2016.

Why Vegetated Mat Systems Dominate

Green Roofs for Healthy Cities, a North American green roof industry association, conducted a detailed market survey in 2016. They showed that mats topped the North American market at 47% followed by trays at 39%. The difference is even higher when it comes to extensive systems 56% for mats vs. 29% for trays.

Lighter weight: 60-150 kg/m2 for mat systems vs. 200-300 kg/m2 for trays
More economical: $150-200/m2 for mat systems vs. $250-350/m2 for trays
No membrane puncture hazards: mat systems are flexible and do not contain any sharp edges or corners
Pre-vegetated mats are easy to cut and conform around drains, penetrations and curved and organic landscapes.

Easy to cut and conform: mat systems are easier and less messy to cut around drains and penetrations, they fit curved and organic landscape design without looking “pixelated” and conform well to 3D contours such as dome or wavy shaped rooftops
Quicker installation: a typical mat is about 10X the size of a typical tray. Mats and baselayers are flexible and much easier to cut than the hard trays. These save as much as 25% labour on large roofs
Easy membrane access: mat systems, especially soilless, can be readily rolled back or cut for membrane access. It is more difficult with trays as they are either interlocked or “jammed” tight over time.

Biodiversity in Trays and Mats

Trays, especially deeper ones (10–20 cm), can accommodate larger plants. Extensive mat systems can also incorporate larger plants with the BioBerm™.

Supplier of more than 2.5 M SQFT Coast-to-Coast

Canada’s leading supplier of pre-vegetated roofs, NLSM customizes to local requirements, offers warranty & maintenance support, provides stormwater calculations specific to location and building/roof type, stormwater test data & related innovative hydrologic modeling. Click here to get started on your next green roof.

More than 85 Years Experience

Next Level Stormwater Management (NLSM) is Canada’s leading supplier of pre-vegetated roofs such as LiteN’Less™ and StormCap™ systems. NLSM’s team has more than 85 years of combined green roof industry experience: helping with stormwater calculations and technical advice, design, planning and maintenance support, assisting with required documentation, issuing P.Eng-stamped wind reports and supplying and delivering the complete system package.

Enjoy this rare bird’s eye view of NLSM green roofs!

Supplier of more than 2.5 M SQFT Coast-to-Coast

Reinventing the Traditional Green Roof for Detention by Sasha Aguilera and Brad Garner in Construction Canada January 2019 Vol. 61 No. 7.

Reinventing the Traditional Green Roof for Detention discusses how detention green roof systems are a reliable and quantifiable rooftop stormwater management tool. The article examines how to use detention technology in dense urban areas to help owners achieve ROI by saving valuable real estate while meeting municipal requirements.

Supplier of More Than 2.5 M SQFT Coast to Coast

NLSM is Canada’s leading supplier of pre-vegetated roofs such as LiteN’Less™, Xeroflor® and StormCap™ systems. We customize to local requirements. Email or call (416) 637-5772 Ext 1.

Read Designing Extensive and Semi-Extensive Vegetated Roofs for Long-term Performance by Sasha Aguilera and Kees Govers in Construction Canada July 2016 Vol. 58 No. 5.

Awarded the 2017 F. Ross Browne Award for “Article of the Year”, this article co-authored by Sasha Aguilera and Kees Govers encourages consultants and contractors to think about their designs and implementations related to vegetated roofs in such a way that systems can perform as long as the building is in use. The article discusses everything from budgeting and design, to access, irrigation, wind uplift, designing for problem areas, care during construction, post-installation, maintenance, vegetation and overburden warranties. To ensure excellence in performance, it’s important the details in design and installation are considered as critically as the systems themselves.

More Than 2.5 Million Square Feet Coast-to-Coast

NLSM is Canada’s leading supplier of pre-vegetated roofs such as Xeroflor, LiteN’Less™ and StormCap™ systems. We are your one-stop-shop. We customize to local requirements, provide wind and stormwater calculations specific to location and building/roof type, P.Eng letters, and other documentation. We offer various products & services including warranty & maintenance support. Click here to start your design.

Read Waterproofing Considerations for Green Roofs by Dr. Karen Liu in Construction Canada March 2012 Vol. 54 No. 2

The article discusses the necessity of a robust and durable roofing system to provide a solid foundation for green roofs and tries to help answer, “What is the best roofing/waterproofing system for green roofs?