Do you need a new roof? Are you wondering what your roof needs and what you’ll pay for?
If you’ve never been through a roof replacement, you’re about to start an expensive process. So, you need to learn as much as possible on the front end to avoid the roofing industry’s dark side.
And there aren’t many things more important than understanding the materials and components that make up a roof. So, what are the different parts of a roof? Why are they important?
For over 30 years, Bill Ragan Roofing has seen way too many homeowners get taken advantage of simply because they didn’t have the right information. This is the last thing I want to happen to you.
So, let’s break down all the parts of a roof, what they do, and the crucial role they play.
Roof decking
Roof decking (also called roof sheathing) is the wooden foundation and the first official roof layer. I call it the foundation because the rest of the components and materials are installed directly on it.
There are two types of decking: plank and sheet. Depending on the span of the rafters, plank decking is made of 1x6 or 1x8 rectangular wooden boards.
Sheet decking (or sheathing) is made of flat sheets of wood that cover more surface area than planks. There are two types of sheet decking: OSB and plywood.
OSB (oriented strand board) consists of wood chips/strips compressed together to form a flat 7/16” sheet, while plywood comes in several different thicknesses (⅜”, ½”, ⅝”, and ¾”). No matter which type of decking is on your roof, the important thing is that it’s structurally sound before installing a new roof.
Drip edge
Drip edge is metal flashing installed on the eaves and rakes to prevent water from getting under the main roofing material at the roof’s edges and going behind your gutters. Your fascia board and roof decking’s edges will rot from prolonged exposure to water without it.
It’s also such an important roof part that it’s required per building codes and must be installed correctly. If it’s left off or improperly installed, your home can actually fail an inspection.
Unfortunately, there are too many roofs without drip edge. It can be left off by laziness or lack of experience, but bad roofers lower their prices by purposefully excluding it from an estimate.
Underlayment
Roof underlayment is a felt or synthetic material installed directly over the entire roof deck to provide a layer of protection if water gets underneath the main roofing material.
(Synthetic underlayment)
There are two types of underlayment: felt and synthetic.
Felt underlayment comes in 15 lb and 30 lb rolls, with the 30 lb option being thicker, stronger, and less likely to tear than 15 lb. However, both felt options absorb water when exposed.
Synthetic underlayment is made out of woven/spun polyethylene or polypropylene that wicks water instead of holding moisture. It’s more durable, holds nails better, and repels water much better than felt underlayment.
So, I recommend spending the extra money on synthetic underlayment for its functionality and water-repelling abilities.
Ice and water shield
Like underlayment, ice and water shield is a waterproof membrane that protects your roof decking from water if it gets under the roofing material. However, it’s specifically installed on/around problem areas prone to leaks and need more protection.
Ice and water shield is mainly installed 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 edges of your roof per building codes to prevent frequent ice dam leaks.
However, this is considered an upgrade in places like our area of Middle Tennessee.
Roof flashing
Roof flashing is metal used to direct water away and prevent it from getting behind areas (walls, chimneys, roof valleys) where the roofing material butts up against something. Without flashing in these areas, your home will have significant leaks and water damage.
It can be made out of any metal type, but aluminum, steel, and copper are the most common. However, prefinished aluminum is the most popular choice for residential roofing due to its affordability.
If you want an upgraded look and more curb appeal, copper is well worth the investment if you have the budget. While roof flashing usually outlives the other components, replacing it when getting a new roof is usually recommended if it’s not in good shape.
Starter shingles
Starter shingles are a pre-cut row of roofing material that goes underneath the first course of shingles on a roof’s edges before they’re installed. It ensures there’s protection between the joints where the shingles are against each other on the edges of your roof.
Starter shingles also have an adhesive to seal the first row of shingles for wind resistance. Just know this explanation is specific to asphalt shingles, but every roofing material has some kind of starter material for the roof’s edges.
Roofing material
Your roofing material is the top layer that makes up the bulk of the roof system you see from the outside. The most popular residential roofing materials are asphalt shingles, standing seam metal roofing, cedar shake roofing, synthetic shingles, and slate roofing.
The one you choose determines your new roof's cost, aesthetic, lifespan, and warranty options. That’s why it’s important to do the research and pick the right one for your budget.
Ridge capping
Ridge capping is installed where two roof slopes meet to seal a roof system at the very top. It will be a pre-bent accessory of the main roofing material that forms perfectly on a roof’s ridge.
Every roof needs the associated ridge capping to prevent leaks. Unfortunately, some roofers avoid using proper ridge capping to keep their costs low.
It’s especially common for asphalt shingles, with some roofers installing 3-tab shingles at the ridge instead of a manufacturer's ridge capping on architectural shingle roof systems. This may keep costs down, but it will lead to a roof leak because they’re not meant to be bent and used this way.
Roof vents
Roof vents allow your attic and home to breathe properly by pulling fresh air through intake vents and pushing out air trapped through exhaust vents. There are multiple roof vent options, but it depends on the type of ventilation system (active and passive).
The most common options for an active ventilation system are turbine vents, power vents, ridge vents with a baffle, or solar-powered vents. For a passive ventilation system, the most common types are static vents (box vents), ridge vents without a baffle, or a gable-end vent.
Just keep in mind that certain vents are better for certain roof styles, so it’s important to discuss the options with your roofing contractor. However, I always recommend an active ventilation system for the functionality it offers.
Pipe boots
A pipe boot (also called roof boot) goes around the base of pipes and other small penetrations coming through your roof. They prevent water from following the sides of pipes into your home.
Depending on the roofing material and type of pipe, pipe boots can be synthetic rubber, plastic, lead, copper, etc. However, the most common type used on residential roofs today is a synthetic rubber called neoprene.
Unfortunately, neoprene pipe boots will need replacing around every 10 years once cracks form prolonged UV exposure to avoid leaks. However, they’ll be cheaper than copper (or another metal), more durable than plastic, and won’t attract animals like lead.
What else do you need to know before getting a new roof?
Now you know the different parts of a roof and why they’re important. This helps you understand exactly what your roof needs and what you’ll pay for when getting a new one.
I guarantee your roof will have problems if it's missing just one. So, make sure every single estimate has a line item for each material and component.
This not only helps you avoid being taken advantage of but also ensures you’re getting a quality roof. However, knowing the different parts of a roof is just the beginning.
Getting a new roof is a big and expensive project. So, you must go into the process as prepared as possible with the right mindset.
That’s why I wrote another article to help you do just that.
Check out 7 Things to Consider Before a Roof Replacement to learn what homeowners should consider and do before getting a new roof.
