When you glance at a typical asphalt shingle roof, what you mostly see are the shingles. However, the shingles are only one of nine components that make up the entire system that is your roof! If you were asked to name all nine parts of your roofing system, you may not be able to because you’re not familiar with them. Informing you is the purpose of this article and the next one (Part 2). We want to be sure that you are aware of these major components and the role of each one, as they all contribute to the safety of your home and your family. Additionally, if you were to get a complete roof replacement, all nine components would most likely be replaced, and it’s good for you to know the scope of the project in advance. After reading the next two articles, you will not only be familiar with all of your own roof’s components, but you will also have a resource for a professional that can help you if you are looking to have your roof replaced.
Decking is the foundation of your roof. It comprises the wooden plywood boards that cover the trusses or rafters. All other components will be installed on top of the roof decking. If you are getting a roof replacement, your roofing contractor may find that your decking needs to be replaced, but he or she will not know that until the old roof is removed. If there are any rotten boards in your decking, those will need to be replaced before any new components are installed.
Roof flashing is a thin sheet of metal. At every place where your roof’s shingles butt up to another material or projection, such as a chimney or a wall, roof flashing will be installed. Your flashing would need to be replaced if its integrity is compromised—showing signs of rust or damage. If you upgrade your shingles from 3-tab to dimensional asphalt, the flashing will definitely need replacing.
Underlayment is installed on top of roof decking and consists of a felt (15 lb, 30 lb, or synthetic) material. Underlayment must be included in a complete roof replacement as it provides additional protection to decking.
Drip edge (an angled piece of metal flashing) is placed over all edges of the roof, under shingles and over fascia board. This helps protect the fascia by channeling the flow of water away from it. Many homeowners don’t know that drip edge installation is governed by building code. If not installed correctly, code non-compliance will cause your roof to fail an inspection. If your roof currently lacks drip edge, or if it is not installed correctly, you will need to correct the situation before you put your home on the market.
Ice and Water Shield
If you get a complete roof replacement, ice and water shields should be installed around any roof penetrations and valleys. These shields consist of a waterproof membrane that protects roofs from damage caused by ice and water. If ice and water shields are not installed, or are installed incorrectly, water may soak through to the decking, causing leaks, rot, and decay.
The top layer of your roof consists of asphalt shingles–the main roofing component that you see. When homeowners think of roof replacements, most only think of the shingles. Please continue to Part 2 of this article to read about three more components that must be considered in a roof replacement project.