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Michael Cosdon's Blog

By Michael Cosdon | Agent in Doylestown, PA

Ever wonder about your roof?

This info is supplied by Bill Squiteri of A-Stat Home Inspection

Roofing 101


The most basic description for a roof is that it functions as an umbrella for the home. Most roofs are not and can not be water or weather tight. They are designed to simply shed water off of the roof and away from the home. Flashing is the component that helps to bring a roof to its closest weather tight state. Roofing systems are not intended to provide insulation for a home (Flat roof vs. Pitched roof) nor does the roof covering itself have a structural role, although most roofs are installed over sheathing and the sheathing itself becomes a structural component once it is attached to the rafters or pre-engineered trusses. The most common defect that you will come across is missing shingles or a hole in a roof from a falling branch or object from the sky. Most, if not all roofing systems require repairs before they ever need to be replaced. Replacing a system has more to do with water damage to the deck sheathing or the age of the roofing shingles themselves. A new roof with water leaking into the home is most likely the result of a flashing defect and not a result of defective roof shingles. Let's look at some common shingles that are used in the marketplace today:







Types of Shingles Found Today






Fiberglass asphalt - These are the most common types of shingles that you will see on homes today. Fiberglass makes up the base material (organic felt is also used in a small percentage of shingles) with asphalt for the body or coating. Asphalt shingles were first manufactured in 1901 and have been commonly used since 1911. The life expectancy of this style shingle is 12-25 years (depending on the quality and thickness of the shingle).



Slate- Slate is a natural stone roofing product. It can be thought of as metamorphosed shale. The main constituents are mica and quartz, but there are typically many other minerals in slate. Slate is quarried in many areas of the world (France, Spain, Wales, India, China, Canada and right here in this great nation, the U.S.A.) Slate can be extremely durable and is expensive to install. It has a life-span from 35-75 years with some roofs in Europe being known to have lasted over 1,000 years.


Wood Shingles or Shakes - Wood roofs were the most common shedding roof system used prior to the advent of asphalt shingles. In some areas of North America, wood shingles are still among the most common roofing materials. Several types of wood have been used over the years with White Cyprus being the best and Red Cedar being next. Some are now available pressure-treated with preservatives. Wood shingles are typically sawn smooth and wood shakes are typically rougher in texture and thicker. Shakes may be split, sawn or both.




Clay Tiles - Clay tiles have been used since the days of the Greek and Roman empires in Europe, China and the Middle East. Clay roofing tiles are expensive and labor intensive to install. They have an indefinite life expectancy. Clay tiles are like slate in that the fasteners and flashings are more likely to fail than the tiles themselves. Clay tiles are made with fine clays shaped in molds while wet, and then kiln baked. Temperatures of roughly 2,000°F bring the clay to a point of vitrification. This means the chemicals in the clay, such as silicas and aluminums, lose their individual identity and fuse together to form a dense, glass-like nonporous structure. The density of these tiles indicates the quality and is determined by the fineness and purity of the clay as well as the duration and temperature of the firing process.


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