Most homeowners never really get up close to their roof and try to understand the inner workings of it. So for many, a roof is just a roof, and it keeps the weather out of homes as well as keeping away any animals from flying or crawling into our homes. If we notice anything about a roof, we only notice how well it blends into the neighborhood, or when a branch has fallen on the roof and needs to be removed. The fact of the matter is that the roof above your head is possibly the most expensive thing you’ll ever have to replace on your home. Therefore, the question is do you ever wonder about the parts of a roof and what is installed underneath the shingles?
Aren’t Shingles Enough?
When your local roofing contractor installs shingles, the new roof installation should always be done in accordance with local building codes and regulations. However, another factor that plays a part in how the shingles are installed is the weather conditions in your area. Your local roofing contractors will often have to take a different installation approach depending on whether it is summer or winter. There are different precautionary steps that need to be taken in different weather conditions in order to ensure no damage is done during the installation.
Another thing you should know is that asphalt shingles are most commonly available in strips of 36 inches long by 12 inches wide. Therefore, each strip has a set of three tabs, which provides the visual shingle effect when installed correctly. Each 3 tab strip has a layer of adhesive just above the tabs. The heat of the sun activates the adhesive, which binds to the layer below and creates a seal that augments the nails when installed.
So, shouldn’t the shingles be enough? The shingles cover the largest area of the roof. However, the shingles hide a lot of essential roofing components that protect your roof against the weather, and keep you warm and dry. In other words, your roof shingles are not always a perfect seal from the rain. Especially as shingles age and curl, rain can be blown underneath them. So what’s going to protect your roof when this happens?
What’s Under the Shingles?
On the surface, your average roof may just look like simple layers of asphalt roofing shingles, however, it’s a lot more complex than the average homeowner may realize. The residential roofing system is composed of layers of different components. These components have different attributes when it comes to restricting wind from entering your home as well as resisting other weather hazards such as rain or hail. The most consistent components that you’ll find installed on your roof are the roof decking, underlayment, drip edge, and flashing.
What are the Parts of a Roof?
Roof Decking (Wood Sheathing)
Roof Decking or roof sheathing is a key roofing component that sits on top of the roof trusses. The roof decking is basically the section on the roof that everything is placed on. Since the roof deck holds everything that’s placed on your roof, expect for the material to be strong enough to hold the weight required and continue to be durable. Just like any other roofing component, the roof deck has many different types of materials. The different types of roof decking materials include steel, concrete, cement, and wood. The way that professional roofing contractors determine the type of roof decking material to use is based on how much weight it needs to carry, which further depends on the roofing components and materials selected. When you consider a residential building, the most common type of roof deck is plywood or groove wood systems. Wood generally stands up to the weight of almost any type of roofing component or material placed on top, although tile may require extra reinforcement.
Roof Underlayment
After the roof deck is installed, we move on to the underlayment for the roof. The underlayment is installed on to the decking, and before the installation of the asphalt shingles. The most common underlayment material is felt. The reason is because it has a durable paper material that is saturated with asphalt. The purpose of the underlayment is for it to provide a temporary barrier against rain and wind before the shingles are installed. It also provides an extra layer of protection in the case of broken or torn shingles. When the underlayment is being installed, it is installed by rolling the material onto the roof horizontally. The underlayment is being installed not only to provide that extra barrier from water or wind, but it also helps the water to shed downward off the roof without seeping through the seams. Most professional roofing contractors will have options for traditional roofing felt underlayment or a more modern synthetic roof underlayment.
What is Synthetic Underlayment?
Synthetic roof underlayment is a high tech, high performance layer of material made with a highly sturdy polypropylene fabric, which is installed the same as a traditional felt underlayment. This new synthetic roof underlayment is known to be a lighter and stronger alternative to a felt roof underlayment. Of course, this new high tech underlayment will cost more than the traditional underlayment, but it will last much longer. Ask your local roofing contractors the differences in price as well as features of all their underlayment options to ensure the best quality for the underlayment of your roof.
What is the Purpose of Roof Flashing?
Moisture is a roof’s worst enemy. The purpose of roof flashing is to prevent any water from leaking as well as to extend the overall life of the roof. Next to chimneys, skylights, or valleys on your roof, a professional roofing contractor will install metal flashing to ensure that there is proper drainage on your roof. You want the water to run down into the shingles and off the roof, rather than pool around whatever might be poking out your roof. Roof flashing is nothing more than a piece of sheet metal that is usually made from aluminum or galvanized steel. In order to prevent water from entering the home, the flashing is placed over the joints in the roof and wall construction. This is important for the reason that most of the causes of roof leaks is due to the fault of poor roof flashing installation.
Roof flashing can endure extreme stresses from extreme weather conditions. Therefore, when installing the roof flashing material there should be extra care taken so that it would be capable of withstanding these extremes. Many local roofing contractors would cut and shape the roof flashing materials from sheet metal. However, homeowners can also choose to have the flashing pre-formed. It is very important to use roof flashing materials that aren’t prone to rust, such as stainless steel, to maintain the integrity of the roof flashing.
In order to see an effective use of roof flashing, the material used should be weather resistant, highly durable, low maintenance and sturdy. The latter quality is very important for the fact that many roofing materials regularly expand and contract on a daily basis. Especially during the dramatic seasonal weather. An interesting thing that you should know is that during the day, the sunlight can raise the surface temperature of the roof, which ends up making the roof expand. However, keep in mind that at night the temperature drops significantly, which ends in a contraction of your home’s roofing materials. More significant expansions and contractions during seasonal changes can have an effect on the framing lumber, which means that your roof flashing material must withstand all these changes to prevent leaks and remain effective.
What are the different types of Roof Flashing?
The 5 types of roof flashing are Drip Edge, Valley Flashing, Vent Pipe Flashing, Step Flashing and Continuous Flashing.
What is the Purpose of Drip Edge?
Drip edge is a metal flashing or piece of aluminum that protects the edges of your roof. It is designed to prevent water from flowing into the fascia so that the underlying roofing components are protected. With that being said, included in the drip edge is a tiny metal projection that is angled away from the fascia. Because of its angled lip, any water coming down the roof would be obstructed from getting into the house. It’s like something of a middle-man between your shingles and your gutter.
Now as a homeowner, you may be questioning does drip edge prevent water damage? The answer is yes. The drip edge’s purpose is to prevent any water damage that can occur under the roofing shingles. Having water enter underneath your shingles can create temporary or even permanent staining. This can also lead to long-term roof deck deterioration, as well as damage to the fascia board.
When water sits on your roof for a long period of time, it can cause damage and the ends of your roof joists and trusses can be compromised. This could eventually lead to structural damage, or leaks getting into your home and causing interior damage becoming an extremely expensive repair.
What is Valley Flashing?
Valley Flashing protects the point on your roof where two slopes come together to form a valley. Valley Flashing is designed to channel run-off water down the roof into the gutter.
What is Vent Pipe Flashing?
This is the metal or rubber flashing around plumbing vent pipes on your roof. As these vent pipes penetrate through the roof, they are common places to find roof leaks. Over time the thin rubber collar on these boots starts to crack or will become damaged and there’s typically no additional seal to keep water from infiltrating around the vent pipe. The roofing cement holding them in place can also fail, creating another pathway for roof leaks.
What is Step Flashing for?
Step flashing protects the seam between a roof and a wall from water penetration and leaks. Small L-shape flashing pieces are woven into the shingles as you work your way up the roof. The flashing fastens the roof cladding into the wall cladding to help keep water out.
For more information on Step Flashing, please visit our step flashing page:
Everything you Need to Know about Step Flashing on Shingle Roofs
What is Continuous Flashing?
Continuous flashing is considered somewhat controversial as there can be issues with it. Most professional roofing companies would recommend the installation of step flashing instead. Continuous flashing was only fairly recently approved by the National Roofing Contractors Association (NRCA). L-shaped lengths of metal that are a few of inches longer than the shingle overlap are installed on top of each shingle adjacent to the sidewall. The flashing is then laced into each shingle course.
What is the Fascia on a Roof?
The fascia board is the panel mounted at the point where the roof meets the outer walls of the house and is often called the roofline. However, most professional roofing contractors refer to it by the name of the main board that carries the gutter, which is the fascia or fascias. The fascia board is the long, straight board that runs along the lower edge of the roof. The fascia is fixed directly to the lower ends of the roof trusses and usually does all the work of supporting the lower edge of the bottom row of tiles. Any guttering will be attached to the fascia boards.
Soffit and Fascia Boards
A soffit is a board that bridges the gap between a home’s siding and its roofline. It’s located under the horizontal fascia board, which holds the gutters. Soffits help provide ventilation for your attic space. The fascia is attached to the edge of the roof and stretches horizontally from one end of the rafters to the other.
The purpose of the fascia board is to prevent water and wind from damaging the interior of the house and the roof. It also supports the gutters and drainage pipes as well as to help enhance the appearance of the house. Failing to clean gutters on a regular basis can cause water to pool, which can damage the fascia and soffit.
Roof Insulation
Roof insulation can take many forms. The most commonly used material is felt or plastic sheeting; sometimes with a reflective surface. These materials are installed directly underneath the other roofing material. Synthetic foam batting or material from recycled paper products can also be positioned or sprayed into roofing cavities to enhance the roof’s insulating properties.
Without proper insulation or ventilation, roofs can begin to experience weather-related problems like ice forming near overhanging eaves. When the ice melts, it can be absorbed into roofing material, causing issues. Called ice dams, these pockets of ice form when heat escapes through the top of the roof, melting snow at the uppermost point. The water then begins to refreeze as it flows down the roof and collects under shingles and other low points. Over time, this can destabilize your shingles, add stress to the roof and destroy drainage systems and gutters.
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