Are you about to get a new roof or roof repair? Do you keep hearing about roof valleys and what they need?
If you ask most people what a valley is, they could most likely give you the right answer. But if you put the word “roof” in front of “valley,” the majority (if not all) of people would have no idea what you’re talking about.
This is understandable, but the truth is that a roof valley is crucial to the functionality of your roof system. And when the time comes for a new roof, or you have a roof leak, you’ll probably hear the term a lot.
So, what exactly is a roof valley? And what do you need to know about it?
For over 35 years, Bill Ragan Roofing has helped homeowners understand everything about their roof. That's why I’ll break down the basics of roof valleys and what to know about them.
By the end of this article, you'll learn:
- What is a roof valley?
- What material is installed in a roof valley?
- What causes leaks in roof valleys?
What is a roof valley?
A roof valley is when two roof facets meet at a slope to form an interior angle to allow water to flow down your roof properly. It's pretty much a V-like channel where different parts of a roof come together.
There are two types of roof valleys: open and closed. However, whether they're open or closed mainly comes down to the type of roofing material.
Closed roof valley
Closed roof valleys mean they are “closed” by installing the the main roofing material over it like the rest of the roof. If you have an asphalt shingle roof, you’ll have closed valleys because shingles are pliable enough to bend so that the facets can tie into each other.
While closed valleys are the go to for asphalt shingles, some homeowners want open valleys on architectural and luxury shingle roofs for aesthetic reasons. However, this increases the price of a roof replacement more than a closed valley because metal is used to close it.
Open roof valley
Open valleys mean they are literally “open,” meaning they don't have the main roofing material installed over the valley. This leaves the valley exposed, which means it needs metal valley flashing to close it.
Open valleys are standard on premium roof materials, such as cedar shake shingles or synthetic shingles. This is simply because these roofing materials can’t bend to “close” a roof valley, which is why the metal valley flashing is needed.
If the look isn’t important to you, prefinished steel is the more affordable option. However, copper is a popular choice for homeowners who really want to raise their home's curb appeal.
What material is installed in a roof valley?
Roof valleys are one of the most leak prone roof areas due to the amount of water that flows through them. So, it's crucial that roof valleys have the right type of material installed in them to prevent leaks.
As I just said, open roof valleys get metal flashing over the valley to transition the two roof facets where the materials meet. However, a closed valley needs something installed before closing it.
(Ice and water shield installed in roof valley before shingles)
A closed roof valley requires ice and water shield installed in the valley over the decking before installing shingles to close it. This waterproof material protects the roof decking if water gets underneath the shingles that close the valley.
At the end of the day, a roof valley shouldn't have problems as long as the right material is installed correctly. However, there's are still certain circumstances where a roof valley leaks.
What causes leaks in roof valleys?
Roof valleys usually won't leak as long as they have the right material installed correctly. However, there are still special circumstances where leaks still happen.
The two most common roof leaks in roof valleys are lack of maintenance and ice damming.
Lack of maintenance
Roof maintenance is crucial to maximize your roof's lifespan and catch potential problems before they start. Well, one of the most roof leaks is when debris is left to sit and build in a roof valley.
Debris (like leaves and sticks) in roof valleys create a dam that back ups water until it gets under the roofing material. And when the debris gets saturated and sits in a closed roof valley for prolonged periods of time, it shortens the lifespan of shingles.
Because of this, it’s absolutely crucial to get your roof valleys cleared out as part of roof maintenance once a year of when the seasons change.
Ice damming
Ice damming occurs when snow and ice freeze down by the gutter line (eaves) to create a literal dam of ice on a roof. When the ice starts thawing, the ice dam blocks water from draining down a roof valley and backs up.
This backed-up water eventually gets underneath the roofing material in the roof valley and leaks inside until it’s warm to thaw out the ice dam at the gutter line. Anytime we get snow or ice, it's guaranteed that we'll get calls for leaks caused by ice damming.
Unfortunately, there’s nothing a roofer can do to stop leaks caused by ice damming when it’s already happening. So, the only thing to do is get a bucket to catch the water coming into your home until everything thaws out.
What are the main parts of a roof system?
Now you know what roof valleys are, the materials needed to prevent leaks, and leaks that can occur in roof valleys. Roof valleys are on most roofs, which means roofers have plenty of experience dealing with them.
However, roof valleys are just an architectural aspect of a roof that must be accounted for when ordering materials and estimating a new roof. There's nothing you can do about them, but it's crucial they get the right materials.
But these materials are a small part of an entire puzzle. So, you must know every piece you'll pay for, where they get installed, and what they do.
That’s why I wrote another article breaking down all the different parts of a roof system.
Check out What Are the Different Parts of a Roof to learn every material and component that goes into a roof replacement.
