3 months ago
I had a great experience with Scarlet Roofing. Their team was extremely knowledgeable, professional, and easy to work with from start to finish. They took the time to answer my questions, explain the work being done,…
Flat Roof / Torch On
Flat Roofs Fail Differently. Here Is How We Build Them to Last.
A flat roof in Surrey or Vancouver lives a harder life than a pitched one. It holds water instead of shedding it, collects leaves and needles, and takes the full force of every winter storm with no slope to help it drain. Built right, with proper falls and a fully welded membrane, it is every bit as reliable as a shingle roof. Built wrong, the problems start quietly and get expensive fast.
We specialize in torch on modified bitumen, the membrane system that suits our climate best for low slope work. On this page you will find a plain language explanation of the system, what it costs around here, how to tell when your flat roof needs attention, and how we install, repair and maintain it. If you already have ponding water or a leak, you can jump to the warning signs below, or just call us and we will come and look.
We are based in Surrey and work across Vancouver and the Lower Mainland, so the pricing and advice below reflect local conditions and local building practice, not generic guidance.
A Fully Welded, Waterproof Membrane
Two and three ply torch on systems for flat and low slope sections, built to shed water for decades.
- Torch on modified bitumen in base and cap sheet layers, heat welded at every seam into one continuous waterproof skin.
- Drainage corrected first. Proper falls to drains or scuppers, with tapered insulation where needed, because no membrane outlives standing water.
- Reinforced flashing at parapets, walls, skylight curbs and roof drains, the details where most flat roof leaks actually begin.
- Open flame work done safely. Fire watch on every torch job, extinguishers on the roof, and heat shields at every penetration.
- Clean handover. Full site cleanup, photos of the finished membrane, and written maintenance guidance.
Torch On Basics
What Torch On Membrane Roofing Is
Torch on roofing is a membrane system made from modified bitumen, which is asphalt refined with rubber like polymers and reinforced with a polyester or fibreglass mat. It arrives in rolls. During installation each roll is heated with a torch as it is unrolled, melting the bitumen so it fuses to the layer below. The result is not shingles that overlap, but a single continuous waterproof skin.
That matters because shingles rely on slope. Water has to run off faster than it can work its way under the laps. On a low slope or flat roof, water lingers, and lingering water finds every weakness. A heat welded membrane does not depend on gravity the same way, which is why it is the right system for flat sections, and why shingles on too flat a slope are a leak waiting to happen.
You will see torch on most often on additions, garages, carports, dormers and commercial buildings around the Lower Mainland. Many homes here are a hybrid: shingles on the main slopes, membrane on the flat garage or addition. We work on both, and we will tell you honestly which system your roof actually needs. If the rest of your home needs shingles, our roof replacement page covers that side in detail.
System Choice
Two Ply or Three Ply: Which System and Why
A torch on roof is built in plies, meaning layers. The two common residential systems are two ply and three ply. Here is how they compare for our climate.
| System | What you get | Typical lifespan | Best fit |
|---|---|---|---|
| Two ply | Base sheet plus granulated cap sheet, fully torch welded | 20 to 25 years | Most residential garages, additions and dormers |
| Three ply | Base sheet, interply sheet, plus granulated cap sheet | 25 to 30 years | Larger flat roofs, roofs with foot traffic, maximum longevity |
The granulated cap sheet is the weathering surface. Its mineral granules shield the bitumen from UV, which is what breaks membranes down over time. Three ply costs more upfront and earns it back in puncture resistance and lifespan. For a typical garage or addition, two ply is the sweet spot. For a full flat roof over living space, we usually recommend three ply, and we will walk through the choice at your quote.
Pricing Guidance
What Flat Roofing Costs in the Lower Mainland
Flat roofing is usually priced by the square foot, because every flat roof is a different size and a different puzzle of drains, parapets and penetrations. These are general market ranges for the Lower Mainland, not a quote for your roof. Your written quote from us will be itemized after we see the roof in person.
| System | Typical installed range per square foot | Notes |
|---|---|---|
| Two ply torch on | $9 to $14 | Most common for residential work |
| Three ply torch on | $12 to $18 | Larger roofs and maximum lifespan |
| Tear off of old membrane | Priced by condition | Disposal included in our quotes |
| Tapered insulation to fix ponding | Quoted per project | Depends on how much fall needs building |
What moves you within or beyond those ranges: roof size, because small roofs cost more per square foot with minimum charges; whether the old membrane comes off or the new system goes over it; how much tapered insulation is needed to correct drainage; access and height; and parapet and flashing complexity. A simple garage rectangle and a parapet wrapped commercial roof are very different jobs.
These are general market figures for installed torch on systems in the Lower Mainland, including labour, materials, flashings and disposal. They are not a binding quote. Every roof is different, which is why our quotes are written and itemized after an on site inspection.
Warning Signs
Signs Your Flat Roof Needs Attention
Flat roofs rarely fail all at once. They send signals first. If you spot any of these, it is worth a look before the next big rain.
Ponding water that lingers
Water still sitting days after rain means the drainage is not working. Occasional shallow puddles that dry out are normal. Lakes that stay are not.
Blisters or bubbles
Raised bubbles in the membrane mean trapped moisture or air underneath. Small ones can be monitored. Large or growing ones need attention.
Cracked or lifting seams
Seams are the most stressed part of any membrane. If you can see gaps or lifting edges, water already has a path in.
Granule loss on the cap sheet
Bare patches where the mineral surface has worn away leave bitumen exposed to UV, which shortens its life quickly.
Stains on ceilings below
Brown rings or drip marks inside almost always trace back to the roof above. The entry point is rarely directly above the stain.
Soft spots underfoot
Areas that feel spongy when walked on suggest wet insulation or decking below. That needs a professional look promptly.
If any of this sounds familiar, our roof inspection will pin down exactly what is going on, with photos you can see for yourself.
Our Process
Our Torch On Installation Process
01
Assessment and moisture survey
We walk the roof, check drainage, and test for trapped moisture in the existing system. What we find decides whether the old roof comes off or the new membrane goes over it.
02
Tear off or overlay decision
If the substrate and insulation are dry and sound, an overlay can work. If moisture is trapped or the deck is damaged, everything comes off. We show you the evidence either way.
03
Substrate preparation
The deck is cleaned, repaired and primed so the membrane bonds fully. This unglamorous step decides how long the roof lasts.
04
Base sheet installation
The base sheet goes down first, fully adhered, creating the foundation layer of the system.
05
Cap sheet torching
The granulated cap sheet is heat welded in overlapping courses. Every seam is fused into one continuous skin, then rolled and checked.
06
Flashings and edge metal
Parapets, walls, drains and penetrations get reinforced flashing and new edge metal. This is where most flat roofs fail, so we spend real time here.
07
Final inspection and water test
We walk every seam, verify drainage, and water test the drains. You receive photos of the finished roof and written maintenance guidance.
Drainage
Flat Roof Drainage: The Detail That Decides Lifespan
Here is the uncomfortable truth about flat roofs: the membrane gets the attention, but drainage decides the lifespan. A perfect membrane under permanent standing water will still fail early, and most manufacturer warranties exclude damage from ponding. When we assess a flat roof, drainage comes first.
That means proper falls to interior drains or scuppers, drains kept clear of leaves and debris, and tapered insulation to build slope where the structure has none. Many of the flat roofs we replace failed not because the membrane was bad, but because water had nowhere to go. Fixing the drainage is often the most valuable part of the job.
After installation, the maintenance is simple: keep drains and scuppers clear, especially each fall when the leaves come down. A five minute check after a windstorm can add years to the roof.
Repairs and Care
Repairs, Maintenance and Recoating
Not every flat roof problem needs a new roof. Seam re welds, patches over damaged areas, flashing repairs and drain reseating are all routine work for us, and we will tell you honestly when a repair is the smart money.
Replacement becomes the right call when blistering is widespread, the insulation below is saturated, or seams are failing in multiple places. At that point patching buys months, not years, and we will say so plainly. Our roof repair and maintenance page explains how we make that call.
On maintenance: an annual inspection, debris and drain clearing each fall, and minimal foot traffic will add years to any membrane. An elastomeric recoating can extend the life of an aging but sound membrane, though it is not a substitute for a failed one. We will give you a straight answer on whether your roof is a candidate.
Further reading: our neutral reference guide Flat Roofing Systems: Materials, Installation, and Maintenance covers every major membrane type, installation methods, and a full maintenance program.
Commercial and Strata
Commercial and Strata Flat Roofing
Offices, retail buildings and strata complexes across the Lower Mainland run on flat roofs, and they cannot shut down for a roofing project. We phase the work and schedule off hours where needed, so tenants and customers are barely affected.
For property managers and strata councils, we offer maintenance plans with scheduled inspections, drain clearing and written condition reports that make budgeting straightforward. Documentation packages for council meetings and reserve planning are part of the service.
If you manage a building with an aging flat roof, a professional assessment now is far cheaper than emergency leak response later. Our roof waterproofing page covers the larger building envelope picture.
Warranty
Warranties on Membrane Systems
Two warranties cover your new membrane. The manufacturer warrants the membrane material against defects, and we register it properly. We separately warrant our own workmanship in writing: if a seam we welded or a flashing we installed fails because of our work, we come back and fix it.
Keeping coverage valid is mostly common sense: keep drains clear, avoid unnecessary foot traffic, and do not let another contractor cut into the membrane without telling us. We explain the terms at handover and leave you with the documents.
Related Services
You May Also Need
Flat Roof / Torch On FAQs
Questions About Flat Roof / Torch On
A properly installed two ply system typically lasts 20 to 25 years here, and three ply 25 to 30 years, with basic maintenance. Annual inspections and keeping drains clear are what get you to the top of those ranges. Our rain is the main factor, which is why drainage matters as much as the membrane.
As general market guidance, two ply systems typically run $9 to $14 per square foot installed in the Lower Mainland, and three ply $12 to $18. Small roofs cost more per square foot, and tear off, tapered insulation and complex flashing add to it. Your written quote from us will be itemized for your specific roof.
For most residential garages, additions and dormers, two ply is the sweet spot of cost and lifespan. Choose three ply for a full flat roof over living space, roofs with regular foot traffic, or when you want maximum longevity. We will recommend one at your quote and explain why.
We schedule torch work for dry conditions and dry in the roof each day, the same rain safe practice we use on every job. A membrane cannot be properly welded to a wet substrate, so we will not pretend otherwise. If weather turns mid project, your roof is protected before we leave.
It depends on how long the water stays. Shallow puddles that dry within a day or two after rain are common and usually fine. Water still sitting after several dry days means the drainage is failing, and that accelerates membrane breakdown. An inspection will tell you which one you have.
Yes. Offices, retail and strata buildings are a regular part of our work. We phase the job to minimize disruption, schedule off hours where needed, and provide the documentation property managers and councils need.
Keep drains and scuppers clear, especially in fall, clear debris a couple of times a year, and have the roof inspected annually. Avoid unnecessary foot traffic and never let anyone cut into the membrane without proper flashing afterwards. That simple routine adds years.
Dealing With A Flat Roof Leak?
Get a free inspection and a clear, written quote.
Client Feedback
What Lower Mainland Homeowners Say About Us
Real, verified reviews from our Google Business Profile, shown exactly as our customers wrote them.