Smart solutions for green roof longevity

By SMT Research.

Advanced monitoring systems are changing the game for green roof sustainability.

Green roofs have become synonymous with sustainable architecture, offering a blend of aesthetic appeal, energy efficiency and environmental benefits. But beneath the lush greenery lies a crucial yet vulnerable component — the waterproof membrane. When leaks occur, the cost of detection and repair can skyrocket, threatening both the integrity of the building and the longevity of the roof itself. The solution? A cutting-edge approach from SMT Research that combines technology and real-time monitoring to safeguard these rooftop assets from hidden risks.

The risk  

In nearly 20 years of structure monitoring, we have found common issues that risk the integrity of large low-slope roofing. The majority of these issues occur as damages to the waterproof membrane during construction. The roof deck is used as a walkway, a staging area for materials and equipment and is open to damages from above.  

We have seen:

• Nails and other building materials embedded in the waterproof membrane.  
• Chemical burns as adhesives used on walls and planters drip onto the membrane.  
• Heavy equipment and scaffolding stored on wooden blocks digging into the protective waterproof barrier.  

All these damages allow water into the roof deck where it can cause structural damage, disrupting the operation of the building and costing owners thousands, if not more, in repairs.  

Above: Damages found in waterproof membranes during construction (Credit: SMT)

What is a leak detection system?  

A leak detection system monitors the health of the waterproof membrane which covers the structural roof deck on a large low-slope roof. Advanced low-profile sensor elements are permanently installed directly on top of the waterproof membrane and connected to monitoring electronics. This system can monitor the health of the membrane from the moment it is installed, through construction as layers of insulation and vegetation are placed on top.  

Above: FutureCast Leak detection system installed within the layers of an inverted/protected roof assembly (Credit: SMT, Go2Productions)

The value of a leak detection system on a green roof is that the now-hidden waterproof barrier can be actively monitored for potential leaks, generating reports that guide building owners on when and where to perform maintenance. Any repairs are significantly less costly due to only removing targeted sections of vegetation, minimizing disruption to the building occupants.  

Case study: Passive leak detection system finds leak

Installing a leak detection system on a green roof begins with architectural drawings. SMT was contracted to install a leak detection system on a mid-rise building in downtown Vancouver featuring an extensive green roof plaza deck.  

Above: Architectural drawings with leak detection system mapped out

Once the waterproof membrane was complete, SMT installed an extensive grid of sensors laying flat on top of the membrane. On this project, the sensors were left installed in a passive state i.e. not actively taking readings of the roof environment.  

Above: Leak detection sensors covering the roof deck, directly on the waterproof membrane (Credit: SMT)

A leak detection scan was performed using a handheld DigiScan device, pinpointing damages to the membrane so they could be repaired before the membrane is covered.  

Above: DigiScan device locates a penetration in the waterproof membrane (Credit: SMT)

The leak detection system becomes part of the roof assembly, covered with a root barrier, drainage mat, insulation and green overburden.  

Above: Green roof installed on top of an inverted roof assembly (Credit: SMT)

The green roof system was completed, with planters placed around the perimeter.  

Above: Completed Green Roof (Credit: SMT)  

When a leak was discovered by a tenant, we returned to site to activate the system and take readings of the membrane environment. Multiple readings with varying levels of rooftop saturation were taken and analyzed.

Above: Portable Leak Detection System Electronics (Credit: SMT)

Data from the leak detection system was used to generate a “heat map” of the waterproof membrane, narrowing a search area for the source of the leak.

Above: CAD drawing illustrating the likely area of the leak (Credit: SMT Analytics)

A small area of green roof was removed, allowing tenants to enjoy the majority of the roof and saving a lot of time and cost.

Above: small area of exposed membrane for leak investigation (Credit: SMT) 

The exposed membrane was scanned with a DigiScan device to pinpoint the leak.  

Above: DigiScan 360 device scans waterproof membrane, giving  a vector towards the leak source (Credit: SMT)  

A damaged pipe was located, with the system also indicating that the pipe was damaged further down on a different level - allowing for a comprehensive repair.  

Above: Damaged pipe located (Credit: SMT)

The roof was re-covered, with the leak detection system used periodically to check for the health of the membrane and the success of the repairs.  

Above: Fully Covered Green Roof (Credit: SMT)

Fully automated monitoring

The best protection for a green roof is a fully automated leak detection system. SMT have now  installed 100’s of fully automated leak detection systems active across Canada and the United States, offering near-live performance data for the waterproof membranes protecting structures with green roofs.  

On one such project, our FutureCast automated leak detection system triggered an alarm for a membrane breach. The system data highlighted a small area of the green roof for removal so that the breach could be found.  

In this instance, the membrane breach had been caused during the installation of the green roof, specifically landscaping stone placed as a walkway and barrier around the perimeter of the extensive green roof. Stones from this barrier were kicked underneath the drainage mat, allowing the full weight of the overburden to press the stone into the waterproof membrane.  

This kind of damage has been seen on multiple sites and is especially pronounced where new details such as lampposts, electrical outlets or benches have been added to the roof.  

A green roof is installed with the mindset of longevity and resilience, yet at its foundation is a waterproof membrane at risk from all the daily activities of a construction site, with damages occurring that may not be obvious until well after construction is complete. Taking great care during installation of green roof elements is a good way to reduce the occurrences of these damages, but a fully automated monitoring system that lasts as long as the roof is the best long-term solution to protecting the roof.

Original article and photo source: SMT Research