There are four main asphalt roofing methods for flat and low slope roofs. Which one you choose depends in part on your budget, as well as the basic design of your roof and a few other factors. Learn more about the available methods so you can choose the one that is best for your building.
Hot Mopped Asphalt
With hot mopped asphalt, the asphalt shingling itself comes in a roll. The rolled asphalt is laid over the roofing substrate. Then asphalt chunks are melted down and the hot, liquid asphalt is mopped over the asphalt roll to fully adhere it to the roof while also creating the waterproof barrier.
Hot mopping is one of the earliest methods of installing an asphalt flat or low slope roof, and it is still in use today because it is both effective and less expensive compared to other options. Keep in mind that installation of hot mopped asphalt can be smelly and time consuming, as well.
Torched Asphalt
Torched asphalt roofing is also sometimes called welded asphalt. This method also uses a roll of asphalt shingling, but the side of the roll that is in contact with the roofing substrate is impregnated with a thicker layer of asphalt. As the shingling is rolled out, the installer uses a torch to heat this layer of asphalt so that it adheres to the substrate.
Although less time consuming than hot mopping, it does still take time to install this style of roof. There will also be seams between the asphalt rolls, which are more prone to leaks.
Adhesive Applied Asphalt
With cold adhesive application, your installer begins by coating the roof with a special adhesive. Then the asphalt is rolled out over the top and smoothed into place. There isn't a lot of odor involved since the asphalt isn't heated. Installation is also relatively quick.
One major benefit of adhesive application is that it can be applied over the old roofing material so there is no need to tear down the roof to the substrate. You can also upgrade from rolled asphalt to single-ply asphalt, which is a wider shingling that results in few if any seams. Fewer seams mean less chance for leaks.
Self-Adhered Asphalt
Similar to adhesive applied, self-adhered systems have the adhesive built into one side of the asphalt roll so there is no need to spread the adhesive on the roof first. Self-adhered can cost a bit more, but the main benefit is an even quicker installation.
Much like adhesive applied systems, you can upgrade to single-ply rolls that have fewer seams.
Contact a roofing contractor in your area to learn more about asphalt shingle roofing and single-ply roofing systems.