Know the Anatomy of your Roof Before Repairing
Entry #2514, June 12, 2013
If you own a home for long enough, odds are that it will eventually require some type of roof repair, or even roof replacement. Although someone with home improvement or construction skills might choose to give it a shot themselves, the vast majority will hire a roofing company, to ensure that it’s done correctly. However, if you don’t know a thing about roofing, it can be quite difficult to make sense of some of the terms you might come across.
Image via: Johnston Architects
Here’s a list of the major components of a roof, along with a brief description of each one:
Decking or Sheathing
Sheathing (also called decking) is a layer of panels that goes over the rafters, usually made of some type of wood materials. This is the layer that the shingles and other layers will be nailed to, while also providing an additional layer of protection.
A dormer is a type of structure that protrudes from a sloped roof. Dormers have a roof of their own and are typically used to surround attic windows, porches and garages. In homes with attics, they can actually add a bit more interior space to an otherwise cramped upstairs room. They can also be used as a means of letting in more natural sunlight and ventilation from above, without the window being at the same angle as the roof.
As its name implies, a drip edge is installed early in roof construction to direct water straight off the roof, rather than down the edges. Without one, water that runs down the edges can warp and rot the wood, leading to otherwise unnecessary and expensive repairs. Most drip edges today are made from aluminum, although they can also be made from a wide range of materials, including plastic and vinyl.
The fascia is simply a trim piece used to cover the ends of the rafters. It’s installed horizontally below the roofline and is the piece to which the gutters are typically attached. Because it’s visible, the fascia is usually painted to match the rest of the house.
Image via: Dan Nelson, Designs Northwest Architects
Flashing includes pieces of metal that act as molding in areas that are prone to heavy water runoff. The idea is to keep water from penetrating the intersecting areas around protruding objects like chimneys and dormers, as well as any vulnerable joints and valleys.
A gable is a roof-style where the walls at each end of the house come up in a triangular shape above the main living area, supporting two identical roof surfaces that meet in a ridge at the top. This type of design is typically less-expensive to build and quite popular, however it may require extra bracing at each end, in areas that are prone to high winds.
A hip is an area where two sloping sections of the roof meet at an outward angle. There are several varieties of hipped roofs that can be created, from simple pyramid-like roofs with equal sides to cross hipped varieties, that resemble two hipped buildings assembled at an angle, as well as some more aesthetically-appealing variations on these designs.
These are the individual beams that make up the roof truss. There are various types of rafters with different names such as “common rafters” and “valley rafters.” These terms describe their particular function or location, within the larger framework.
The ridge is simply the top edge of a roof, where the two main sloped sides meet, that extends the full length of the structure. Ridges are often ventilated and usually covered with shingles, to protect against any type of buildup that might result in a costly leak.
This is the skeletal framework around which the roof is constructed. Most roof trusses are made of wood and because there’s so much flexibility in how a truss is put together, a wide variety of roof-shapes can be created from it.
While some roofs are constructed with the ends hanging off the edge and uncovered, a horizontal piece called a soffit is used on others, primarily for cosmetic reasons, to cover the open area beneath the overhang. Some soffits are ventilated, which can extend the life of the roof by keeping it cooler in hot weather.
Image via: Simpson Design Group Architects
A starter strip is made of shingle material in a full row, adhered to the edge of the overhanging
portion of the roof. Its purpose is to keep the underside of the next layer of shingles from being lifted up by a strong gust of wind, which could potentially pull the above layers of shingles up with them.
Also known as tar paper or felt paper, underlayment is applied directly over the sheathing to keep the wood dry, while the rest of the layers are added. Once the shingles are in place, it simply serves as an additional protective layer. The name “tar paper” is used because traditional underlayment (still widely in use today) is basically a paper-like product coated with liquid asphalt, although there are several alternative materials today that are commonly used for the same purpose.
Image via: Paul Moon Design
A valley is an area where two sloping sections of the roof meet, creating an inward angle. They’re a common area for leakage because of a tendency for branches, leaves and other debris to accumulate there, impeding proper drainage.
Although there are other terms you might encounter when dealing with a roofing company, these are the most important ones, because they give you a better idea of what’s involved in repairing or replacing a roof. It goes without saying that a well-informed customer can make better decisions and avoid paying for something they don’t really need, especially with something that’s already quite involved and expensive.
Michael M. Bazile is a retired roofer who has lots of free time. A passionate blogger, he now loves to help others by sharing his home improvement wisdom on various blog sites.
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