What is torch down roofing material? How is it made?

What Is Torch Down Roofing Material? How Is It Made?

Roofs can be made from any number of materials: asphalt shingles, metal panels, concrete tiles – and the list goes on. Each roof material has its own benefits, and every material is made and installed in a different way. One less-familiar roofing material you may not know a lot about is called torch-down roofing. Sometimes, it is referred to as modified bitumen roofing. Keep reading for a closer look at this roofing material, how it is made, and how it is installed on a roof.

Torch Down Roofing: Explained

The name “torch down roofing” comes from the fact that the roof material is sealed down with a torch. The heat from the torch not only seals the roof material to itself, but also to the roof deck below. 

So, what is the material which is being torched down? Essentially, it is made from an asphalt product called bitumen. Every company uses a slightly different formula to make their torch-down roofing. Some add additional polymers to increase durability or toughen it up. Torch-down roofing comes in rolls, which the roofer will unroll onto the roof surface

How Torch Down Roofing Is Installed

Torch-down roofs are multi-layer roofs. First, your roofer will install a layer of insulation on the roof deck. Depending on the material chosen, this insulation may be screwed down or attached with an adhesive. Next, they’ll install a vapor barrier, which protects the insulation and roof deck from moisture. Then comes the overlay board, which is the surface to which the asphalt material will be attached.

Once the overlay boards are in place, your roofers will unroll the first layer of modified bitumen, which is known as the base sheet. They’ll use heat to adhere it to the overlay board. Next, they will add the second sheet of bitumen, which is known as the cap sheet. This layer is thicker and sturdier.

As the roofers unroll the cap sheet onto the roof, they will use a torch to seal it to the underlying base layer. Once they’ve worked their way across the whole roof, the roof will essentially be complete. They’ll finish up by adding some flashing around chimneys and vents. Two layers are usually used to flash a torch down roof. The first will be a layer of tough bitumen material. The second will be metal – usually steel.

Torch-down roofing is a relatively affordable roofing option. The material itself tends to be affordably priced. Plus, the installation process is fairly seamless, so you won’t pay as much for labor as you would with other roof materials.

The Advantages of Torch Down Roofing

One big advantage of torch-down roofing is its high level of water resistance. As long as it is applied properly, it forms one consistent, waterproof barrier over your entire roof. Compare this to a shingle or tile roof, which has many little seams that water is sometimes able to penetrate.

Torch-down roofing also works well in many different climates. As the temperature changes, it stretches and contracts, which allows it to resist tearing. This flexibility makes torch-down roofing a rather damage-resistant roofing option in climates that see a lot of fluctuations in temperature.

Torch-down roof material is UV-resistant, so it won’t break down easily when exposed to the sun. It is also quite reflective, which keeps the interior of the building cooler and may result in lower AC bills.

Repairing a torch down roof is quite simple. The roofer can just put a patch of the cap sheet material over the damaged area and adhere it with a torch. As such, repairs are generally affordable.

The Disadvantages of Torch Down Roofing

While torch-down roofing is a great choice for many buildings, it is not perfect. One small downside is this: the installation process, which requires a propane torch, does come with some risk. If you decide on a torch-down roof, make sure you hire a company with plenty of installation experience. The torch needs to be handled with skill to prevent fires and heat damage.

Another disadvantage is the potential for separation between the base layer and cap layer if the two are not adhered properly. Again, this should not be an issue if you hire an experienced installer – but it is a big reason never to DIY a torch-down roof installation. 

Torch-down roofing tends to work really well on low-slope roofs, flat roofs, and roofs in wetter climates. It’s relatively affordable, easy to repair, and energy-efficient. If you think a torch-down roof may be a good choice for your building, contact S&S Roofing in the Pacific Northwest. We’re experienced, professional roofing contractors, and we promise to treat your home like it’s our own.