Are you considering using torch-down roofing as an alternative to the more conventional, and often more expensive forms of roofing material? If so, you may find the following information very useful. In this article we will give a brief description of torch-down roofing, as well as step-by-step instructions for installing one of these types of roofs.
What is Torch-Down Roofing?
You may think that torch-down roofing is a rather new form of roofing material, but actually torch-down roofing has been used commercially for about 40 years now, although only recently has this type of roof been used in residential applications. Experts in the roofing trade often refer to torch-down roofing as “modified-bitumen roofing,” a name given to the material because of what it primarily consists of, and the process for installing this type of roof is actually fairly simple. In fact, torch-down roofing often takes less time to install than conventional composition shingles, gravel roofing or built-up tar roofs.
Torch-down roofing consists of a modified polymer-based bitumen membrane which in essence is asphalt combined with a very strong fabric, usually fiberglass, polyester or a combination of the two, and the end result is a very durable roofing material that can last, in some cases, upwards of 20 years.
Torch-Down Roofing Installation Instructions
The first thing you’ll need to accomplish, especially if this is a re-roofing project, is to establish what the local building code says about re-roofing over existing roofs. In some areas there are regulations prohibiting the practice of re-roofing over more than two layers of roof. This information can usually be obtained online by visiting the city code section associated with your area. If this is a first-time roof, naturally you can skip this step.
Before you even begin laying any material, you’ll first want to thoroughly inspect the top of the roof to make sure it is structurally sound. Also the roof must be completely smooth, free of any sharp objects, rocks, blisters and low spots. Once the surface area of the roof is completely smooth and free of dirt and debris, you’re ready to begin.
The first step is to secure the metal flashing along the edges of the roof. Once the flashing is secure, apply a good coat of primer to the metal. Primer will help the roofing material completely adhere to the flashing.
For a roof to have the longest life-span, roofing experts suggest a three-ply roofing system, which is what we’ll explain here. You can start by applying a 43-pound fiberglass base sheet to the surface of the roof, securing the sheet with cap nails at about every four to six inches. Make sure the base sheet lays out nice and smooth with no noticeable high or low spots.
Now you’re ready to install the first layer of the bitumen membrane. Beginning at the low end of the roof and working parallel to the slope, place the membrane carefully over the base sheet, extending it at least 3 inches over the edges of the roof. After you have completely installed the membrane on the surface of the roof, use your roofing knife to cut the membrane even with the edges of the roof. Make sure that the layer you’ve applied is tight by stretching it to remove any wrinkles.
Next you’ll want to roll the sheet halfway back in preparation for the torching process. Make sure it is rolled tight and even so that it can be moved back into place as it is heated.
With your torch in hand, position it about one foot in front of the roof and between the membrane and the base sheet. Fire the torch using an “L-shaped” movement across the material. As the membrane, which is largely asphalt, gets hot, it will begin to liquefy. At this point push the membrane forward using your foot to allow the heated membrane to successfully bond with the fiberglass base sheet.
When you reach the end of the membrane sheets, use a tool to gently raise the material, and apply heat to fully melt the bitumen in the membrane. If you need to, press the material evenly into place using either a tool or your foot.
To install a second and third layer of membrane, repeat the process, making sure to overlap the sheets by six inches for the second row and three inches for the third row. Apply the roofing material over the metal flashing, and if need be, installed the modified bitumen sheets to create a ridge at the top.