Is it time to replace your asphalt shingle roof? Are you wondering what accessories (also called components) your new roof needs on top of the shingles?
The truth is that roofing accessories are just as important as the shingles themselves. They come together under the surface like a puzzle to protect your home from water intrusion.
So, what are all the roofing accessories? What do they do? Why are they important?
For over 30 years, Bill Ragan Roofing has taken pride in helping homeowners understand the important pieces that every asphalt shingle roof needs. So, let’s look at all the accessories your new asphalt shingle roof needs.
By the end, you’ll know what they are, where they’re installed, the different types, and why each one is important.
Roof decking
Roof decking (also called roof sheathing) is the wooden foundation (plywood or planks) on which a roof is installed. While it’s not necessarily an accessory, decking is the official first layer of an asphalt shingle roof system.
There are two types of roof decking: plank and sheet. Plank decking is made up of rectangular wooden boards, with the size being either 1x6 or 1x8 based on the span of your rafters.
Sheet decking (or sheathing) is made of flat sheets of wood that will be either OSB or plywood. OSB (oriented strand board) consists of tightly compressed wood chips/strips that form a flat 7/16” sheet, while plywood comes in several different thicknesses (⅜”, ½”, ⅝”, and ¾”).
Any rotten or compromised roof decking must be replaced before installation can begin. On top of that, plank decking with more than a 1/8” between the planks must be replaced per the shingle manufacturer’s installation instructions.
Drip edge
Drip edge is metal flashing installed at the roof’s edges (eaves and rakes) to prevent water from getting underneath the asphalt shingles and going behind your gutters. It’s so important that it’s required per building codes and must be installed correctly.
Just know a pre-bent aluminum fascia or rake molding acts as drip edge, so it won’t be required in some cases. However, it’s required to ensure your roof is up to code and to avoid prolonged water exposure to your fascia and decking edges.
Unfortunately, drip edge is commonly left off roofs from laziness, lack of experience, or knowingly excluded to lower prices. That’s why it’s always crucial to check your estimate to ensure it’s included in your roof replacement.
Underlayment
Underlayment is installed directly over roof decking as a layer of protection if water gets underneath the asphalt shingles. You have two options for underlayment: felt or synthetic.
(Synthetic underlayment)
Felt underlayment is made of a mixture of textile materials that come in either 15 lb or 30 lb rolls. Both are fine, but the 30 lb option is thicker, stronger, and less likely to tear than 15 lb.
Synthetic underlayment is made out of woven/spun polyethylene or polypropylene that wicks water and doesn’t hold moisture like felt. It’s more durable, holds nails better, and repels water much better than felt underlayment.
I always recommend spending the extra money on the functionality and better water protection synthetic underlayment offers.
Ice and water shield
Ice and water shield is another waterproof membrane that protects your roof decking from water if it gets under the roofing material. Unlike underlayment that covers the entire roof deck, it’s installed on/around specific problem areas that need extra protection.
Ice and water shield is should be used in roof valleys, around penetrations, against walls, and on roof pitches below a 4/12. However, certain areas above the snowline in the US also require two rows along the roof edges per building codes to prevent frequent ice dam leaks.
Even when it’s not a required code, it’s a common upgrade in areas with yearly snow or ice storms.
Roof flashing
Roof flashing is a metal material that directs water away to prevent it from getting behind or under areas (walls, chimneys, roof valleys) where shingles butt up against something. It can be made of any metal type, but aluminum, steel, and copper are the most popular.
Steel is the most common choice for residential asphalt shingle roofs due to its durability and affordability. However, copper is well worth the investment if you have the budget.
Roof flashing usually outlives the other accessories listed here, but I always recommend replacing it when getting a new roof.
Starter shingles
Starter shingles are an asphalt accessory installed on your roof edges underneath the first row of shingles. They provide protection between the joints where shingles butt up against each other.
The adhesive on starter shingles also seals the first row of shingles to your roof edges for stronger wind resistance. Even though this is specific to asphalt shingles, every roofing material has some kind of starter accessory.
Ridge capping
Ridge capping is an asphalt accessory installed where two roof slopes meet to seal an asphalt shingle roof at the very top. This accessory is pre-bent to fit perfectly over a ridge to avoid cracking that can happen when bending asphalt-based materials.
However, some roofers avoid using proper ridge capping to keep their costs lower than the competition. This is mainly done by installing 3-tab shingles at the ridge instead of a manufacturer's ridge capping on architectural shingle roof systems.
They’re not meant to be bent and used this way, so it will eventually cause a roof leak. Just like starter shingles, every roofing needs the associated ridge capping to ensure your roof is completely sealed.
Roof vents
Roof vents pull fresh air through intake vents and push out trapped air through exhaust vents in your attic to allow your home to breathe. There are plenty of roof vent options, but the options vary based on the type of ventilation system (active and passive).
Just keep in mind that certain vents are better for certain roof styles, so it’s important to discuss the options with your roof. No matter the roof vent you choose, the most important thing is that your attic has the right amount of ventilation.
If it doesn't, your asphalt shingle roof is guaranteed to fail prematurely, plus your energy bills will increase, and mold can form in your attic.
Pipe boots
A pipe boot (also called roof boot) is a roofing accessory that goes around the base of pipes and other small penetrations to prevent water from entering your home. Depending on the roofing material and type of pipe, pipe boots can be synthetic rubber, plastic, lead, copper, etc.
While there are multiple options, the most common type used on asphalt shingle roofs is a synthetic rubber called neoprene. Neoprene pipe boots are affordable, but the only downside is that they need replacing every 10 years or so once cracks form UX exposure to avoid leaks.
However, they’re still much cheaper than copper (or another metal), more durable than plastic, and won’t attract animals like lead.
What are the different types of asphalt shingles?
Now you know the roofing accessories that every asphalt shingle roof needs. Every single thing listed here must be combined with asphalt shingles to prevent leaks.
If even one is missing, I guarantee you’ll have big problems down the road. While accessories are important to protecting your home, the asphalt shingle determines how long a roof lasts, its cost, the warranties, and much more.
So, it’s crucial to pick the right one. But you can’t do this without knowing how the three types of asphalt shingles match up.
Check out 3-tab vs. Dimensional vs. Luxury Asphalt Shingles to learn which asphalt shingle is right for you and your upcoming roof replacement.
