The Dangers of Torch-Down Roofing
Torch Down Roofing Is Playing With Fire
If you have a commercial flat roof, one of many options to consider would be to have it covered with the torch down roofing material known as modified bitumen. If you are considering adding torch down roofing because you believe that it would be better for your roof based on your research or advice from a friend or other commercial roofing contractors, please consider these additional facts beforehand.

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What Is The Torch Down Roofing System?
First, let’s get into what exactly torch down roofing is. Torch down roofing is still one of the most commonly used roofing types for flat commercial roofs. The official name of this type of roofing is modified bitumen. It is a rolled roofing product that consists of a tough waterproof roof membrane embedded in a thick layer of asphalt. The rubbery additives with high-quality resins in the asphalt allow the roofing to expand and contract, whereas some other roofing systems would just crack. This roofing type can bond tightly to metal flashings and move them, while also maintaining the bond. This flexibility is the main benefit of modified bitumen and why it has been a success.
The reason why many property owners and local roofing contractors went with torch down roofing is that it’s impermeable to rainwater and is also resistant to otherwise damaging UV rays. The roofing would not melt or gather any large puddles of rainwater, so it’s already weatherproof to a good extent. Not only that it’s extremely durable because the combination of asphalt and resin makes it resistant to punctures and other damages. While all this is good, we’re going to talk about the negatives of torch down roofing and why it is dangerous.
What Exactly Is A Roofing Gas Torch?
Gas torches are most commonly used in commercial low slope roofing to apply polymer modified bitumen membranes. It is important to understand exactly what the roofing torch components are, including its regulator, to operate it safely. Furthermore, you would need to understand propane and other liquid petroleum fuels and you might see why this is a dangerous process.
Why Do People Use Torch Down Roofing?
One of the biggest reasons people install torch down roofing is due to its strong resistance to leaks. When it is compared to self-adhering single-ply roofing membranes and traditional asphalt roof underlayment, torch down roofing’s heat welding mechanism ensures protection from leaks because of its completely melted torch down surface.
Self-adhering roofing is easy to install. Unfortunately, some adhesive layers in a handful of seams can come loose especially if the roofing material has reached the last 3-5 years of its lifespan. However, polymer modified bitumen torch down roofing does not have these issues until it gets worn down over time.
Another reason people go with torch down roofing is because of its UV protection and insulation. Torch down roofing has an airtight seal and exceptional material density. One distinct advantage of torch down roofing is its UV reflective capability. In turn, torch down roofing provides excellent insulation for any property.
Torch Down Roofing Is A Poor Financial Investment
Torch down’s cost is high and it provides a very poor return on your investment. It is one of the most expensive roofing systems compared to the other alternatives and its life expectancy is quite short. While torch down roofing repair costs and maintenance costs may seem low at first, the frequency of these financial outlays increases exponentially until the whole roof needs to be replaced in a very short period of time.
Consider Alternatives To Torch Down Roofing
Torch down roofing is the application of bitumen to the roof surface. However, the bitumen used in this process needs to have something added to it to stabilize its inability to expand and contract. Originally, the answer was asbestos but this has since been found to be extremely problematic and dangerous, as any professional local roofing contractors can tell you. Afterwards, manufacturers came up with a solution in the form of polymer modified bitumen, though this product also has its own issues. Modified bitumen in torch down roofing uses plastic-type modifiers, not rubber, and it comes with a host of dangers. The largest is its potential to catch fire.
Modified bitumen has several problems of its own in its composition, but any torch down roofing, which utilizes a torch and propane tank, is incredibly dangerous. The risks are very high and the odds aren’t in your favor if you are using flames in this way, for a long period of time. Accidents tend to happen frequently. It’s actually been made illegal for roofers to use torch down roofing at all in a number of states because of how many fires were started as a result.
There are several more modern alternatives to torch down rolled roofing which you should consider if you have a commercial flat roof that you are looking at replacing. EPDM roofing systems, TPO roofing systems and PVC roofing systems are considered by experienced local roofing contractors to be superior options which are far safer to install and maintain.
Sometimes with roofing systems, people feel that they have to replace like-for-like. That is absolutely not the case! When replacing an old roof, usually your old roofing system will be completely removed anyway, as installing a new roofing system over another could compromise the integrity of the new system and also potentially invalidate some warranties. If you are having your old roofing system stripped off anyway, now is the perfect opportunity to consider better alternatives.
Here are a few helpful links to some alternative roofing systems that we would recommend:
Torch Down Roofing Poses Significant Fire Risks
When torching down a roof, it is so easy to make a mistake with the torch that could result in disaster. Consider roofers that are torching down a roof and they accidentally overheat something in the attic insulation, for instance. They end their work for the day, not noticing the smoke coming out of the soffit vents. Before long, that smoldering material in the attic heats up and starts a fire that quickly spreads throughout the dry, hot attic and then to the rest of the structure.
Almost every roofer and commercial roofing contractor you speak to that has experience in torch down roofing has some crazy tale to tell about it. It could be the serious injury of themselves or a colleague, or perhaps it nearly (or actually) caused a serious fire at a property they were working on. The more you talk to roofers about it, the more you realize what an incredible risk you are taking every time you go out on a roof with flaming torches.
The installation of torch down roofing requires the use of powerful propane as mentioned before and this poses substantial fire risks. Fires caused by propane roofing torches is a daily occurrence in today’s world. Most of these fires are immediately extinguished since it is mandatory to have a fire extinguisher present at all times. Some torch down fires, however, are not immediately put out and then the fire department has to be involved. There are a few bigger disasters, such as the following below, which are examples of some very serious fires that were caused by torch-down roofing that attracted significant media coverage.

New Westminster Columbia Torch Down Roofing Fire

East Vancouver Church Torch Down Roofing Fire
Torch Down Fires Can Smolder For Hours Before Erupting
A major issue with torch down caused fires is that when propane torch flames are allowed to go down an attic space, the fire can smolder for hours before erupting. With regard to the above image of the New Westminster fire, flames entered the attic area prior to the crew finishing for the day. The fire then smoked for 10 hours before finally erupting in the middle of the night. A similar case happened to the church.
In New York City, they made propane torches on a roof a felony. In June 1999, the NYC chief fire marshal Louis F. Garcia signed on to make it illegal to use a torch on a wooden roof deck in the city. The reason being NYC experiencing an average of 35 torch-caused fires a year. Therefore, legislation made it a felony to use a propane torch on a roof.
Roofing Liability Insurance Issues
Many local roofing contractors do not carry the appropriate insurance to be working with torch down roofing on commercial properties. Roofing liability insurance with coverage for torch down roofing is very expensive and a lot of local roofing companies will just not bother worrying about it. If you do not check that your preferred roofing contractor is carrying the appropriate insurance coverage, this could leave you in a very difficult position if something were to go wrong with your commercial torch down roofing installation. Be very careful about the local roofing contractor you call in for such a risky process. The cheapest commercial roofing contractors are definitely not always the best option, particularly when it comes to torch roofing.
Prevent Roof Fires During Torch Down Projects
For commercial roof owners who still prefer to have a torch down roof here is how your chosen roofing contractor can prevent any fires. As mentioned before using an open-flame torch to install torch down roofing systems can pose a fire risk. Torch down roofing consists of layers of modified bitumen, most often adhered to layers of fiberglass using a flame torch. Torch down roofing is only used on flat or low-slope roofs.
Because this process is still popular with some roofing contractors, there are a few who would still continue to use this rolled roofing system. They may feel as though this process has an ease of installation and that it has adaptability. So for commercial roofing contractors who believe that torch down roofing is still the best way to go, OSHA has developed standards that can help prevent these types of fires.
Torch Roofing Guidelines
As experienced commercial roofing contractors, the Infinite Roofing team strongly advises against using torch-down roofing but here are some regulations and best practices if you still feel that is the best option. A fire extinguisher is needed within 50 feet of anywhere where more than 5 gallons of flammable or combustible liquids or 5 pounds of flammable gas are being used on the job site. No one on a job site can be more than 100 feet from a fire extinguisher at all times. There must be at least one fire extinguisher for 3,000 square feet of work area.
All flammable or combustible debris must be located well away from flammable liquids or gases. Combustible scrap and debris must be removed regularly during the course of a job. Piles of scrap and debris must be kept at least 10 feet from any building. A fire watch person should be posted to immediately address any possible smolders or flare-ups. The fire watch person should remain on post 30 minutes after the torch-down job is finished for the day. While the precautions spelled out in these construction regulations are mandatory, local roofing companies and other roofing professionals should be aware that these are just the minimum advised requirements and extreme caution should be practiced at all times. You can never be too careful. Local roofing companies should be aware that they could face steep fines for ignoring these regulations.
The OSHA guide to Roof Fire Protection & Fire Prevention can be found here:
https://www.osha.gov/sites/default/files/2019-03/fireprotection.pdf