Torch-on membrane roofing is one of the most durable waterproofing systems available in New Zealand. Used extensively for commercial buildings and high-traffic areas, it provides heavy-duty protection against water ingress.

This guide explains how torch-on membrane systems work, their advantages and when repairs or replacement may be needed.

What Is Torch-On Waterproofing

Torch-on waterproofing uses modified bitumen membranes that are applied using an open flame gas torch. The flame heats the underside of the membrane as it is unrolled across the roof surface, causing the bitumen to melt and bond directly to the substrate.

This creates a fully bonded, seamless waterproofing layer with no adhesive joints. The overlapping seams are also torched together, providing continuous waterproof protection across the entire roof surface.

Torch-on systems typically use SBS (Styrene-Butadiene-Styrene) modified bitumen, which gives the membrane excellent flexibility, elasticity and resistance to thermal movement. The membrane is reinforced with polyester or fibreglass for added strength.

Advantages of Torch-On Membranes

Fully Bonded Installation

The flame-applied process creates a continuous bond between the membrane and substrate. There are no adhesive joints that can fail over time — the membrane is fused directly to the surface.

Exceptional Durability

Torch-on membranes are among the most durable waterproofing systems available. They can withstand heavy foot traffic, UV exposure and mechanical stress without degrading.

Multi-Layer Application

Torch-on can be installed in multiple layers for added protection. Two-layer systems provide redundancy — if the top layer is damaged, the base layer continues to waterproof.

Excellent Thermal Performance

The thick profile of torch-on membranes provides natural insulation and noise dampening. The dark surface also helps with snow and ice melt in cooler climates.

Strong Repair Capability

Torch-on repairs involve torching new membrane material directly over the damaged area, creating a permanent bond. This makes repairs reliable and long-lasting.

Proven Commercial System

Torch-on has been the standard for commercial and industrial waterproofing worldwide for decades. It is trusted for large roof areas, plant rooms and high-traffic zones.

Where Torch-On Is Used

Torch-on membranes are used across a wide range of applications in Auckland and throughout New Zealand:

Commercial buildings with large flat roof areas
Industrial warehouses and factories
Multi-level apartment complexes
Plant rooms and areas with heavy foot traffic
Residential flat roofs requiring heavy-duty protection
Parapets, upstands and complex roof detailing
Internal gutter linings requiring long-term durability

Torch-on is particularly well-suited for areas that need to withstand regular foot traffic, mechanical equipment, and heavy rainfall.

Torch-On Repairs

Torch-on membranes are designed to last 20–30+ years, but like all roofing systems, they can develop issues over time. Common torch-on repairs include:

Blister Repair

Air pockets trapped during installation can form blisters over time. These are cut open, dried, and patched with new torch-on material.

Split and Crack Repair

Structural movement or impact damage can cause splits. Torch-on patches are applied over the damaged area to restore waterproofing.

Seam Re-Torching

If seams start to lift or separate, they can be re-heated and re-bonded using the original torch-on process.

Flashing Renewal

Flashings around walls, parapets and penetrations are common failure points. These can be re-torched or replaced without disturbing the main membrane.

If your torch-on roof is leaking or showing signs of wear, our team can assess the issue and carry out professional repairs. Contact us for roof repairs in Auckland.

Torch-On Membrane Roofing