2ply Torch oN Roofing
Let's TalkWhat is 2-ply torch-on roofing?
2-ply torch-on roofing is a two-layer SBS modified-bitumen membrane system for flat and low-slope roofs. A reinforced base sheet is fastened or torched to the deck, then a granulated cap sheet is heat-welded over it with a propane torch, forming one continuous waterproof skin with no open seams. In Metro Vancouver it is the most common flat-roof system, and a properly installed 2-ply torch-on roof lasts 25 to 30 years. Pro Torch Roofing has installed torch-on membrane across Vancouver, Burnaby and the North Shore for over 25 years — it is the only flat-roof system we specialise in.
Why torch-on is the right flat roof for Vancouver
Vancouver receives roughly 1,150 mm of rain a year and flat roofs hold standing water for days at a time. Torch-on performs well here for four measurable reasons:
- Fully bonded plies. The cap sheet is heat-welded to the base sheet across its entire surface, so there are no open laps for wind-driven rain to work through.
- Cold flexibility. SBS-modified bitumen stays flexible to about -30°C, so it survives the coastal freeze-thaw cycle without cracking.
- UV resistance. The mineral-granule cap sheet does not soften or break down in summer sun.
- No hot tar. There is no odour or fumes, so occupants do not need to leave the building during installation.
Skylights, HVAC curbs and drains can be added later and flashed into the membrane. Compared with single-ply TPO or EPDM, torch-on is heavier, more puncture resistant, and far easier to repair locally because most Lower Mainland roofers carry SBS material.
What a torch-on roof costs in Vancouver (2026)
A new 2-ply torch-on roof in Metro Vancouver typically costs $10 to $20 per square foot installed, so a 1,500 sq ft flat roof usually lands between $15,000 and $30,000. The main variables are whether the old roof can be overlaid or must be torn off, the number of drains, curbs and parapets to flash, any insulation or tapered-slope package, and roof access. Overlays sit at the low end; full tear-off with new insulation sits at the high end.
For a number specific to your roof, use our flat roof cost calculator or book a free on-site measure. We quote in writing, with the membrane manufacturer and warranty term named on the estimate.
How a 2-ply torch-on roof is installed
A typical 1,500 sq ft residential torch-on roof takes two to four working days, weather permitting. These are the five stages we follow on every job.
- 01Inspection and tear-off decisionWe check the deck, drains and existing membrane. If the old roof is dry and sound it can be overlaid; if the deck is wet or soft it comes off.
- 02Deck prep and insulationRotten plywood is replaced, drains are cleared and any insulation or tapered-slope package is laid so water runs to the drains.
- 03Base sheetA reinforced SBS base sheet is mechanically fastened or torch-adhered to the deck with overlapped, sealed side laps.
- 04Cap sheetThe granulated cap sheet is rolled out and heat-welded to the base sheet across its full surface, producing one continuous membrane.
- 05Flashing, primer and inspectionEvery drain, curb, parapet and wall is flashed with custom sheet metal and two-ply membrane detailing, then the whole roof is walked and documented.
Torch-on vs TPO vs EPDM for Vancouver flat roofs
All three are used in BC. For most residential and strata roofs under about 10,000 sq ft, 2-ply torch-on is the most durable and the easiest to repair.
2-ply torch-on (SBS)
- Layers
- 2 bonded plies
- Lifespan
- 25 to 30 years
- Installed cost
- $10 to $20 / sq ft
- Best for
- Homes, strata, small commercial; roofs with many penetrations
TPO
- Layers
- Single ply
- Lifespan
- 15 to 25 years
- Installed cost
- $9 to $15 / sq ft
- Best for
- Large open commercial roofs where reflectivity matters
EPDM
- Layers
- Single ply
- Lifespan
- 15 to 25 years
- Installed cost
- $8 to $14 / sq ft
- Best for
- Budget commercial roofs with few penetrations
Torch-on roofing questions, answered
How long does a torch-on roof last in Vancouver?
A properly installed 2-ply torch-on roof lasts 25 to 30 years in the Vancouver climate. Lifespan drops sharply if drains are left blocked or if the roof was installed as a single ply.
How much does torch-on roofing cost per square foot?
In Metro Vancouver, 2-ply torch-on runs $10 to $20 per square foot installed in 2026. Overlays and simple rectangular roofs are at the low end; tear-offs with insulation and many penetrations are at the high end.
What is the difference between 2-ply and 3-ply torch-on?
2-ply uses a base sheet and a cap sheet and is the standard for BC flat roofs. 3-ply adds a second base sheet for extra thickness on high-traffic or high-risk roofs; it costs roughly 15 to 20 percent more and is rarely necessary on residential roofs.
Can torch-on be installed over an existing roof?
Yes, if the existing roof is dry and the deck is sound. A moisture scan or core cut during the free inspection tells us which. Wet insulation must be removed or it will rot the new deck from underneath.
Is torch-on roofing safe? Does it use an open flame?
It does. That is why torch-on should only be installed by crews trained in hot-work procedures, with fire watch and extinguishers on the roof, and by a contractor whose liability insurance specifically covers torch application. Pro Torch Roofing carries $5 million in liability coverage that includes hot-work roofing.
Does torch-on roofing smell during installation?
No. Torch-on uses no hot tar, so there is no strong odour and occupants do not need to leave the building.
Can a torch-on roof be done in winter in Vancouver?
Yes, on dry days above about 5°C. The membrane cannot be applied to a wet deck, so winter jobs are scheduled around the forecast and tarped between work days.
What warranty comes with a torch-on roof?
Pro Torch Roofing provides a written workmanship warranty and installs manufacturer-backed SBS membrane systems such as SOPREMA, whose material warranties are registered in the owner's name. The exact term is stated on every estimate.
Torch-on roofing across the Lower Mainland
We install torch-on membrane roofs throughout Greater Vancouver from our base in Burnaby. Pick your city for local details, or browse completed torch-on projects.
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