Roofing Basics – Ultimate Guide to Roof Components

Alex KotsyubaRoofing

Roofing Basics - Shingle Roof Components

The roofing system on your home is one one of the most critical parts of your home simply because it keeps all of the other components dry! Knowing how to properly replace your roof will save you from unwanted leaks to the interior of the home and properly divert water, protect from sitting snow and ice, as well as protecting the roof from high winds. Wether you are replacing the shingles on the roof of your home or simply want to know more about the individual components on your roof, we are here to help. Below is a detailed breakdown to help you understand each roof component and all of the materials needed to replace the roof.

1. Roof Decking/ Sheathing

Roof Components - OSB Roof Plywood

OSB Plywood

Roof Components - CDX Real Plywood

CDX Plywood

Roof Components - Zip System Roof Panels

Zip System Roof Panels

Different Types of Plywood on Roofs

There are different types of roof sheathing or decking that may have been installed on your home. If you need to replace the roof decking because it is moldy, soft, or warped, you want to match the same thickness and style that you currently have on the roof. The only exception is if you are completely replacing all of the decking. Keep in mind, the roof decking is not typically replaced during a roof replacement unless it is compromised. The most common types of sheathing are shown below.

OSB (Oriented Strand Board) - The most popular and cost effective roof decking is composed of multiple layers of wood strands or flakes that are compressed together along with wax and resin adhesive. Although OSB has quickly become the favorite choice on the market, it is not always the best option in certain situations. Joists that are 24” on center versus the standard 16” can cause the OSB plywood to sag over time and many municipalities deem it as not “up to code” for 24” on center rafter installation for roof decking.

Real Plywood (CDX) - Much like OSB, plywood comes in 4x8 sheets. Unlike OSB however, instead of wood strands or flakes, it is multiple layers of wood veneer glued and pressed together. Plywood comes in different grades, “A” being the best finish grade plywood, while “D” is the roughest. CDX plywood is typically used on roof decking as it will be covered up by underlayment as well as shingles. One side is “C” graded plywood, while the other side is “D” graded. Hence the “CD” in CDX. The “X” in CDX stands for “exposure” meaning that is can withstand a bit of moisture, but only for a short period of time. Prolonged exposure will cause he plywood to warp significantly, rot and potentially delaminate(the separation of the individual layers of veneer).

Zip Sheathing (A newer option) - Zip System roof sheathing has become a popular option recently, especially in rainier climates. Although a more expensive option, it claims to save you from having to install a waterproofing barrier on top of it. The water resistant barrier helps to aid as a moisture barrier and all of the seams are required to be sealed with the ZIP System flashing tape. Many roofers are using this option, although we would be cautious in using the system without proper ice and water barrier in critical climates as any overdriven nails or improperly installed flashing tape can still cause leaking to occur. Zip Sheathing would only be a good option if you are doing a roof on a new home that is being built or an entire roof section where the sheathing is to be replaced. For more information on Zip Sheathing, you can visit the Huber Engineered Woods website.

2. Drip Edge

Roof Components - Roof Metal Drip Edge

Different Sizes of white drip edge on the roof (1", 1.5", 2")

Importance of installing Drip Edge

The drip edge is an “L” shaped piece of metal that is installed on the perimeter of the roof after the old roofing system is removed and the roof decking is sound. While it is typically made out of galvanized steel, it can also be purchased in aluminum as well as copper. Most times, it comes painted in white or brown but can also be custom ordered in a variety of colors to match the color scheme of your home. The drip edge serves multiple purposes and is now a part of code in most areas. It also comes in different widths, allowing it to be flexible and specific for every type of roof as well as roofing system.

Advantages (Pros) of Drip Edge
1. The drip edge allows water to properly run off of the roof away from the facia.
2. It creates a nice “clean” and finished look.
3. If aluminum facia wrap is installed onto the facia, it helps to hold the wrap to the facia.
4. It protects the roof from wind driven rain which pushes water around on the roof in ways that it would normally not flow.
5.The drip edge, when combined with ice & water barrier, seals the surface and does not allow water beneath the surface, keeping the roof sheathing dry.

3. Roof Underlayments

Roof Components - Roof Felt Paper

Roof Felt Paper

Roof Components - Roof Synthetic Underlayment

Synthetic Underlayment

Roof Components - Roof Ice & Water Shield

Ice & Water Shield

Types of roof underlayment and key characteristics

Once the drip edge is installed around the perimeter, you are ready for the installation of the roof underlayment. There are a wide variety of roof underlayments that are available on the market today and each type of underlayment is meant to serve a specific purpose. Although the underlayment is not visible once the shingles are installed, it serves a critical purpose in ensuring that the surface is waterproofed and protected in the long run. Installing the wrong type of underlayment at critical areas or not installing it at all can cause water to penetrate the surface and cause leaks on the interior of the home.

Felt Paper Underlayment (Asphalt Saturated Felt)

Felt paper comes in #15 and #30 felt with the #30 or 30lb felt paper being the thicker and heavier felt paper of the two. Naturally, the 30lb felt paper is thicker and therefore less prone to ripping. Felt paper is typically installed over the roof decking with staples or cap nails.

Advantages (Pros) of Felt Paper
1. A major advantage of this type of underlayment is that it is the most cost effective option, especially for “tight on the budget” roof installations.
2. It is easy to snap chalk lines on it and the chalk lines themselves are more visible.

Disadvantages (Cons)
1. Rips easily during installation Can absorb water and cause the roof to ripple/wrinkle and shingles will not lay flat.
2. The surface is slippery, therefore extra precaution is needed during installation to ensure safety.
3.Typically weighs more than other underlayments, making it more difficult to handle.

Synthetic Underlayment (Non-Bitumen Synthetic)

Unlike felt paper. synthetic underlayments are stronger, moisture resistant and manufactured from polypropylene or polyethylene. Each roofing manufacturer typically carries their variation of the synthetic underlayment. Synthetic underlayments can be further broken down into “non-breathable” as well as “breathable” underlayments. The breathable style of underlayment is usually installed in areas where the attic space is under-ventilated. If moisture or condensation comes up from the inside, regular synthetic underlayment will trap the moisture causing mold to develop on the decking.

Advantages (Pros) of Synthetic Underlayment
1. Much stronger than felt paper
2. Weighs less for easier handling
3. A better waterproofer
4. Does not warp and wrinkle like felt paper
5. Safer to walk on (holds better to decking)

Disadvantages (Cons)
1. Usually more expensive than felt paper.
2. Some types of synthetic underlayment can get fairly slippery if wet.
3. Since this is a fairly new product on the market compared to felt paper, different brands have different formulations for the product so there is no standardized manufacturing process. This may affect the overall performance in the long run due to lack of regulation.
4. Chalk lines can be easily erased off of the underlayment depending on the texture/ makeup of the specific product.

Ice & Water Underlayment (Rubberized Asphalt)

Just like felt paper and synthetic underlayment, Ice & Water underlayment comes in a roll and is installed in combination with felt paper or synthetic underlayment. The underside of the ice and water underlayment typically has a sticky surface that goes directly onto the decking and comes with a peel off membrane which makes it “self adhering”. Ice & Water underlayment typically comes in two variations; granular and smooth. The granular underlayment has a “sand like” texture that gives it more of a grip. It tends to be thicker than the smooth surface or “film surface” underlayment. Many roofing contractors prefer the granular underlayment with their standard installations as it easily rolls out and seals to the surface.

Many roofers like to use smooth surface underlayment such as Grace Ice Shield on problematic areas like valleys, around skylights, or lower pitch roofs as it has the ability to aggressively seal to the surface it is being applied on. Although smooth surface underlayment is lighter, it is often more difficult to install since it does have an extreme grip to it and you often only have one chance to apply it onto the surface properly, with no wrinkles.

Advantages of Ice & Water Underlayment (Pros)

Since it is “self adhering”, the seal to the decking allows for better waterproofing, especially on low slope installation (2/12-3/12 pitch). The better the quality of the Ice & Water Shield, the better it seals to the surface as well as around the nail heads.

Advantages (Pros) of Synthetic Underlayment
1. The only disadvantage of Ice & Water underlayment is that it can be more expensive than your standard underlayment, especially if you are purchasing Grace Ice & Water Shield.
2. Cheaper versions of Ice & Water underlayment can be less effective and the granules tend to easily come off and extra precautions have to be taken during installation to ensure safety.

Installation Tip - In order for the Ice & Water shield to work properly, make sure to have a clean, debris free surface when you install it. This will maximize the the adhesion of the material to the decking. Also, as with shingle installation, the Ice & Water shield should be installed in temperatures above 40 degrees fahrenheit.

4. Roofing Nails

Roof Components - Different Types of Roof Nails

Types of roofing nails

When it comes to installing asphalt shingles, most roofers use smooth galvanized steel nails. It is the most popular, as well as the most affordable option on the market. There is an option to use stainless steel nails to install shingles, although they are often times double the price. Stainless steel nails are often the better choice in rain climates or near bodies of salt water as they will not rust over time.

When it comes to ridge vent installation, many roofers will use smooth nails to hand nail the ridge vents or just nails the ridge with the same nails they use on the shingles. Over time, wind and moisture tends to lift the nails up and the vents can become loose and lift or fall off causing roof leaks. The best solution for this is to use ring shank nails on the ridge vents so that they are more secure.

When working around the chimney, masonry nails may need to be used to secure the flashing to the chimney. It is important to use the right type of metal for the nail depending on the type of flashing that is being used as some nails can corrode certain types of flashing causing leaks to occur.

5. Types of Roof Shingles

Roof Components - 3 Tab Shingles

3 Tab Roof Shingles

Roof Components -  Architectural Shingles

Architectural Roof Shingles

Roof Components - Designer Roof Shingles

Designer Roof Shingles

Different types of roofing shingles and key characteristics

Asphalt Roof shingles can be broken down into 3 categories; 3 tab shingles, architectural shingles and performance/designer shingles. Although all three types of shingles are meant to waterproof the roof of your home, each comes at a different price point and varies in overall quality, lifespan and warranty coverage.

Starter Shingles / Rolls

Starter shingles are a must on any type of roofing system being installed. They can be installed on the eves as well as rake edges. At minimum, they should be installed on the eves to prevent water from penetrating the surface at the seams. Starters are typically installed under the first row of shingles. The starters can either be starter shingles, or come as a roll. Although not an ideal option, some roofing contractors will take a regular shingle, cut the top off and use that as the starter shingle. Some will use the entire shingle and flip it upside down and use that. The downside to this is that a regular shingle does not come with a tar strip on it, which allows the shingle above it to seal to the starter, helping to prevent blow offs.

3 Tab Shingles

Composed of one flat layer, a 3 tab shingle is made up of 3 uniform tabs. When installed, they have a uniform, non dimensional look to them. They are also thinner and have a typical wind rating of 60 MPH. 3 tab shingles are usually the cheapest option of the three types of shingle. Unfortunately, due to all of these factors a shorter roof lifespan is to be expected when compared to the architectural and performance shingles.

Key Characteristics of 3 Tab Shingles
1. One flat layer with 3 uniform tabs.
2. Typical wind rating of 60-80MPH
3. Sold at a budget friendly price point.
4. Non-dimensional, uniform look.

Architectural Shingles

Architectural shingles, when compared to 3 tab, have many added benefits that make them an appealing choice Sturdier and heavier compared to 3 tab shingles, architectural shingles have a higher wind rating of up to 120MPH winds. Unlike the 3 tab shingles, they also have a dimensional look with varied colors built into the shingle to give them more of a curb appeal.

Key Characteristics of Architectural Shingles
1.Built in mat or fiberglass core
2. 3 dimensional look for added curb appeal
3. Thicker and composed of a minimum of two layers.
4. Better wind rating (110 MPH)
5. Better fire rating
6. Some have algae-resistant granules built into the shingles.
7.Longer lifespan (typically 30 year warranty)

Performance & Designer Shingles

Similar to standard architectural shingles, the performance and designer shingles are usually the highest grade of shingles available. There are different grades of architectural shingles with the performance and designer shingles being manufactured to have a longer lifespan as well as better curb appeal. They are often designed to mimic the look of slate and wood shakes with pronounced dimensions as well as more color variation within the shingle itself. They outperform other grades of shingles but the only drawback is that they come with a much higher price tag.

Key Characteristics of Performance & Designer Shingles
1.Thicker than standard architectural shingles
2.Comes with a higher wind rating (130MPH+)
3.Often times more impact resistant against hail
4.More pronounced with more color variation
5. Built in algae resistant granules
6. Best fire rating
7.Better warranty (Up to 50 years)

6. Flashing / Step Flashing

Roof Components - Step Flashing

Step Flashing

Roof Components - Wall Flashing

Wall Flashing

Roof Components - Chimney Flashing

Chimney Flashing

Types of flashing found on the roof

Although the flashing is not always seen on the surface, it is a critical component of any roof installation. Step flashing usually comes in a minimum size of 4x4x7 with 4” going up the side wall and 4” above the shingle and is covered by the next shingle. This allows water run along the edge of the wall and not penetrate beneath the surface. Wall flashing works in the same manner and creates a water tight barrier. Wall flashing as well as flashing installed around the base of the chimney is most often custom bent to size on a break to ensure proper fit. If you are planning to replace the roof yourself and do not have a break on hand, most building supply stores sell prefabricated flashing or can bend it for you to size.

7. Pipe Boots

Roof Components - Pipe Boots

Roof Pipe Boots are not all the same quality!

Pipe boots, or pipe collars are installed around sewer pipes as well as electrical poles to prevent water intrusion. There are many types of pipe boots on the market today. The standard pipe boots that are installed by roofing contractors in the Albany, NY area have a rubber gasket that tends to start cracking and deteriorating well before the lifespan of the roof shingles is over. It is well worth the extra money to install a better pipe boot as it will save you upwards of thousands of dollars in repairs in the long run. Keep in mind, the metal flashing surrounding the pipe boot itself should be properly nailed and flashed with ice and water shield to prevent water to run under the flange and down the pipe.

8. Roof Vents

Roof Components - Roof Vents

Different types of roof vents

Roof vents, when installed properly on the roofline will serve their purpose over the life of the roof. As with pipe boots, it is best to flash them properly with ice and water shield. If installing new vents, always try to install them away from critical areas like in valleys, near side walls or other vents. It is always better to install new vents rather than re-using the old ones. The original vents typically rust and become discolored over time. They are also bent when stripping the shingles on the old roof and may not sit flat on the surface of the roof.

8. Roof Ridge Vents

Roof Components - Ridge Vents

Roof Ridge Vent Types

Ridge vents, when properly installed, will allow hot air and any moisture to escape the attic cavity through the roof peak. Ridge vents are a critical part of the roofing system and work in conjunction with the soffits to allow air to freely circulate in the attic cavity. When there is inadequate air circulation in the attic cavity, mold can develop on the roof decking as well as on the rafters. If no remediated, mold can lead to serious health issues. Keep in mind, not all ridge vents will produce the same results when it comes to waterproofing and ventilation. We prefer the vinyl ridge vent system that Owens Corning manufactures simply because it maximizes airflow while making the peak completely waterproof.

Although there are many different roof components available on the market, it makes sense to do your homework to see which components work best for your home. If hiring a roofing contractor to do the work, make sure that they have enough experience to be able to offer a roofing system that would be best, specifically for your home. Keep in mind, even the best roofing materials, improperly installed, will cause the roof to leak so it is important to have the right person or company to complete the work.

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