Hot Mop Roofs Vs. Torch Down Roofs

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Hot mop roofing and torch down roofing are both popular roofing options for flat-roofed structures. Both of these options provide an effective way to waterproof a roof, creating a base that will stand up to weather while keeping the inhabitants of the building dry. The procedure for applying each varies, as do the cost and life span, making an understanding of the two options important before you invest in either one.


Installation Process

To install hot mop roofing, roofers lay a synthetic base layer, top it with a felt layer, then pour liquid tar on the roof and spread this sealing compound with a mop, which gives the process its name. To install torch down roofing, roofers roll out sheets of a bitumen-containing material. As they roll the material out, they hit it with the flames of a torch, melting it and allowing it to adhere to the roof surface, creating a watertight barrier.


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Life Span

Hot mop roofing has a life span of 15 to 20 years, making it a process that you will not soon have to repeat. The life span of torch down roofing is similar, lasting 15 to 20 years with proper installation. With two comparable life spans, those seeking a new roof can't pick a winner on this criterion alone.



Hot mop roofing is generally the cheaper of the two options, although only by a small margin. Though slight, however, the difference is significant enough for those on a tight budget to keep in mind as they make their roofing selections.


Ease of Installation

Neither of these two roof types is particularly easy to install; however, torch down roofing is slightly easier than hot mop roofing. Because installing hot mop roofing involves so many steps and requires the roofers to toil over molten tar, the process is often more difficult than torch down roofing. Torch down roofing, on the other hand, consists of fewer steps and, while roofers will still be exposed to the heat of the torch, they will not have to use liquid tar.


Potential Hazards

Aside from the always present hazard of taking a tumble from the roof, these two roofing processes each provide different hazards for roofers. The primary hazard associated with torch down roofing comes from the use of fire. If roofers aren't careful, they can inadvertently start a fire with the torch they are using as they roof. Hot mop roofing also presents a hazard. Roofers who engage in this process are exposed to fumes of molten asphalt for an extended period. Because these fumes can have negative effects on human health, this repeated exposure can present a problem later in life.