What Is Torch-On Roof Waterproofing?
Torch-on roof waterproofing is a membrane system applied using heat to bond bitumen sheets directly to the substrate. The underside of the membrane is heated with a gas torch, allowing it to adhere securely and form a seamless, watertight layer.
This system is especially effective for low-pitch or flat roofs where water drainage is slower and waterproofing performance is critical.
Key Benefits of Torch-On Roofing
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Durability: Designed to last 15–25+ years with proper installation and maintenance
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Waterproof reliability: Seam-welded joins reduce the risk of leaks
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UV resistance: Suitable for exposed roofing areas without additional coatings
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Flexibility: Handles structural movement and thermal expansion
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Cost-effective: Strong long-term value compared to liquid membranes
Compared to liquid-applied systems, torch-on membranes provide consistent thickness and fewer application variables, which reduces failure risk on larger commercial roofs.
Where Torch-On Systems Are Used
Torch-on waterproofing is commonly installed on:
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Flat and low-slope residential roofs
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Apartment and commercial buildings
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Roof decks and balconies (as a base system)
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Concrete gutters and box gutters
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Parapet walls and detailing areas
In Auckland’s climate—with frequent rain and humidity—these systems perform reliably when installed correctly.
The Installation Process
Proper installation is key to achieving long-term performance:
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Surface preparation: Cleaning, drying, and priming the substrate
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Base layer installation: Often a primer and base sheet for adhesion
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Membrane application: Torch bonding the waterproofing layer
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Detailing: Flashings, upstands, penetrations, and edges sealed carefully
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Inspection: Ensuring full adhesion and watertight integrity
The most common failure points are penetrations, internal corners, and poorly prepared substrates—not the membrane itself. Skilled detailing is what separates a 5-year system from a 20-year system.
Compliance and NZ Standards
Torch-on systems in New Zealand must comply with:
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NZBC E2/AS1 (External Moisture)
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Manufacturer specifications (e.g. ARDEX, Nuraply, Viking)
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Approved installation methods and warranties
Working with qualified installers ensures compliance and eligibility for product warranties.
Maintenance and Lifespan
To maximise lifespan:
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Schedule annual inspections
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Clear debris and ensure drainage outlets are free-flowing
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Repair minor damage early to prevent water ingress
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Avoid unnecessary foot traffic without protection
A well-installed and maintained torch-on roof can last decades with minimal issues.
Why Choose A Plus Group NZ
At A Plus Group NZ, we specialise in professional torch-on waterproofing systems tailored to Auckland conditions. Our focus is on:
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High-quality materials from trusted NZ suppliers
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Precision installation and detailing
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Long-term performance and durability
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Clear communication and reliable service
Whether it’s a new build or a re-roofing project, we deliver waterproofing solutions that protect your property.
