subject: The Basics Of Roof Replacement [print this page] At this point in history, we have yet to develop a roofing system that will last forever. Therefore, at some point each of us will more than likely have to deal with a roof replacement.
The roof is the most important structural component of any building. Without a quality, weather-tight roof, all other components of a building will be destroyed in short order. Paint, drywall, framing, and flooring are just not engineered to withstand Mother Nature. Interior spaces need protection from he elements.
Here are some roofing terms that will be helpful during the decision making process:
Square - Unit of measure commonly used in roofing and siding that equals 10 feet by 10 feet or 100 square feet. Roofing material is generally sold per square, and roofers generally calculate costs and price based on the total number of squares.
Decking or Sheeting - The flat layer of material attached to the roof joists. A lot of older homes and buildings have wood planks. Most modern residential buildings have plywood or orient strand board (OSB) decking that is manufactured in 4 x 8 sheets (sometimes called sheeting). The most common thickness of roof decking used today is 7/16. Underlayment and shingles are attached to the roof decking.
Asphalt shingles Organic based shingles discontinued in 2006 due to poor performance. The term asphalt shingle is still used today often times as a misstatement. Many roofers refer to post 2006 shingles as asphalt shingles where the technical term is really composition shingle.
Composition Shingle - Modern shingles manufactured with an asphalt/fiberglass mixture. The asphalt/fiberglass body of the shingle is covered with a protective granular layer.
Granular Layer The ceramic top coating of a composition shingle that provides UV/impact/weather protection and also provides the color.
Architectural / Laminated / Dimensional Shingle - All terms refer to the modern popular shingle manufactured with several layers (laminated) of asphalt/fiberglass material that provide added strength, longevity, and a shake-like appearance.
Underlayment - The layer of material applied to the roof decking prior to installing shingles. The most common underlayment is felt (tar) paper in 15 or 30 pound variety. Although, there are many new synthetic products available that waterproof/breathable material (similar to house wrap) that has been tested to have advantages in longevity and performance over traditional roofing felt.
Ice and Water or Weather Barrier - Adhesive on one side underlayment used to protect roof eaves and valleys from ice dams and water back ups. Installing ice and water barrier is a critical step in preventing damage to roof decking by water and/or ice backing up from the gutters and going underneath the shingles. Most municipal building code requires a minimum of the first three feet of roof eaves to be covered by ice and water barrier.
Roof Vent - The outflow space left open on the highest portion of roof to provide for proper ventilation and release of hot air. The inflow vents are normally located in lower portions of the roof, such as soffit vents or gable vents, and allow for the intake of cooler, outside air. Roof vents can be either the older style box type, or a modern ridge vent system. The structure and style of your roof will determine which style of vent will work best.
Make sure you do your homework prior to discussing your project with a roofer or roofing company. There are a dizzying amount of choices for shingles, underlayment, vents, and decking, and a huge variation in cost for each type of material. Each component is critical, as each piece should work together as a system once installed properly.
