Torch-On SBS vs TPO Roofing — Real-World Comparison & What to Choose
The following text presents the author's perspective as a roofer who performs flat roof work throughout Vancouver.
Flat roofing in Vancouver is unforgiving. The first point of system failure occurs in this area before any product defect becomes apparent because the system fails first when moisture remains constant and debris accumulates and water pools and the system lacks sufficient time to dry out.
The two roofing systems which I receive the most requests to evaluate for residential flat roofs and strata buildings and light commercial projects are Torch-On SBS and TPO. The written documents contain functional information which can be used for their intended purposes. The actual behavior of these elements differs significantly when they are implemented on real roof systems.
The evaluation uses actual operational results for its assessment instead of depending on manufacturer brochures or laboratory test data. The focus is on which roofing systems in Vancouver will maintain their structure throughout the years and what specific failure points occur when systems breakdown and which selection criteria should be used for different exposure levels and usage patterns and ownership objectives.
Why Flat Roof Material Choice Matters in Vancouver
Vancouver is one of the most demanding environments in Canada for flat roofing.
Key realities we deal with every year:
- The soil faces difficulties because wet conditions persist for long periods which prevent the soil from drying out properly.
- The storm brings heavy rain which blows horizontally instead of falling straight down.
- The combination of moss and needles and debris remains on roofs throughout multiple months.
- Ponding water on low-slope and flat roofs
- The system maintains a fixed temperature range which causes materials to expand and contract instead of creating individual freeze-thaw events.
Flat roofs don’t benefit from gravity the way sloped roofs do. Water sits. Debris collects. Seams and transitions do all the work.
The selection of membranes stands as the most critical factor for this area because it outpaces other locations.
Homeowners, strata councils, and builders usually ask:
- Which system leaks less?
- Which lasts longer?
- Which is easier to repair?
- Which gives the best long-term value?
The roof usage and exposure to damage will determine the selection rather than choosing between modern-sounding products.
What Torch-On SBS Roofing Is
The modified bitumen system known as Torch-On SBS roofing has operated in Vancouver since the past century because of its enduring popularity.
What SBS means
The three-letter code SBS stands for Styrene-Butadiene-Styrene which functions as a rubberized asphalt modifier. The membrane structure obtains its elastic properties and its ability to withstand both stretching and cracking when objects move through it.
In simple terms:
The material properties of SBS match rubber characteristics better than those of plastic.
How Torch-On SBS is installed
The Torch-On system consists of two layers which sometimes extend to three layers.
- Base sheet — torched or adhered to the substrate
- The cap sheet receives fire application at its base to create a waterproof layer.
A propane torch melts the underside of the membrane, bonding it directly to the layer below. The correct application method produces a single unbroken waterproof barrier which extends continuously.
The seams of this product use heat fusion instead of adhesive for bonding.
Why SBS has a strong track record in Vancouver
- The system enables users to perform body movements which prevent the system from splitting into different parts.
- The material continues to operate correctly when it stays submerged in water at all times.
- The system operates dependably when it detects all entry points and connection points.
- The system operates without using adhesives which become weak when exposed to water.
- The repair process can be performed without disrupting the current membrane structure.
The proper installation and detailing of SBS roofs in Vancouver enables them to maintain their condition for twenty to thirty years.
What TPO Roofing Is
The single-ply membrane TPO (Thermoplastic Olefin) has become the preferred choice for commercial building projects since its introduction to the market 15 to 20 years ago.
What TPO actually is
- The seams of the product receive heat-welding through the application of hot air.
- The material comes in large sections which users can install.
- The material surface appears white or light in color because it reflects light.
The waterproofing system of TPO operates differently from SBS because it uses a single material instead of asphalt-based layers which need multiple layers for protection.
How TPO is installed
TPO can be installed in three main ways:
- The system depends on mechanically fastened connections which use screws and plates that extend through the membrane.
- The material stays in place through complete adhesion which bonds it to the substrate.
- The system uses ballasted installation which occurs only in specific non-residential areas of Vancouver.
Seams are welded together with hot-air welders. The weld quality is entirely dependent on:
- Proper temperature
- Clean, dry surfaces
- Skilled installer technique
How They Compare in Real Vancouver Performance
Water Resistance & Ponding
Torch-On SBS:
- The system operates through multiple layers which create backup systems.
- Seams are fully heat-fused asphalt to asphalt
- The system allows water to remain stationary for long durations before it will experience any breakdown.
- The surface damage which occurs at a small scale will not trigger any immediate leakage problems.
TPO:
- Single-layer system — no redundancy
- The welds need to be flawless because any imperfection will compromise the water tightness of the seams.
- The ponding water creates ongoing stress on the seams of the roof.
- The weld requires absolute integrity because any form of damage will result in immediate fluid leakage.
Roofer’s Bottom Line
The flat roofing design in Vancouver serves as a method to control risks instead of following any specific material requirements.
The Torch-On SBS system provides users with three essential benefits which include its ability to withstand stress and its capacity to absorb damage and its established track record of enduring for many years.
The right choice depends on:
- The roof will maintain what level of wetness.
- How complex the detailing is
- How long you plan to own the building
- What level of tolerance you maintain when it comes to dealing with equipment breakdowns and repair requirements
Select the roofing option which will provide the best real-world performance for your roof rather than choosing based on appearance.
