Roof valleys are crucial in a roof’s overall structure and functionality. They are the sloping channel where two sections of a roof meet, creating a seam between them. This article explores the differences between open and closed roof valleys, shedding light on their characteristics, benefits, drawbacks, and practical considerations.

Understanding Roof Valleys

Definition of Roof Valleys

A roof valley is where two roof slopes intersect, creating a narrow channel that allows water to flow off the roof. It is a critical component of any roofing system as it helps prevent water from stagnating or seeping into the underlying structure.

When it comes to roofing, various elements work together to ensure the durability and functionality of the system. One such element is the roof valley. This architectural feature plays a crucial role in directing water away from the roof, protecting it from potential damage caused by leaks and excessive moisture.

Roof valleys are typically found where two roof slopes meet, forming a V-shaped channel. This design allows rainwater and melting snow to flow smoothly down the roof and into the gutters or eaves. By effectively channeling water away from the roof and foundation of a building, roof valleys help maintain the structural integrity of the entire roofing system.

Role of Roof Valleys

Roof valleys serve as a drainage system, redirecting rainwater and melting snow away from the roof and foundation of a building. By effectively channeling water down to the gutters or eaves, they help protect the roof from potential damage caused by leaks and excessive moisture.

Imagine a heavy downpour hitting your roof. Without a properly functioning roof valley, the water would accumulate in the valleys, creating a pool of stagnant water. Over time, this standing water can seep into the underlying structure, leading to rot, mold, and other moisture-related issues. A well-designed roof valley ensures water is swiftly directed away from your roof, preventing potential damage.

Moreover, roof valleys enhance the overall aesthetics of a roof, adding visual interest and architectural appeal. They create distinct lines and angles, breaking up the monotony of a large roof surface. Whether you have a traditional gable roof or a more modern hip roof, roof valleys add depth and character to the overall design.

Roof valleys can also be an opportunity to showcase your style and creativity. With various roofing materials and colors available, you can highlight the valleys using contrasting shingles or metal flashing. This can create a visually striking effect, making your roof stand out.

Open Roof Valleys

An open roof valley, also known as an exposed valley, is characterized by the absence of any covering material over the joint area. Instead, the roofing materials on both sides of the valley meet, exposing the seam.

This type of valley construction allows rainwater to flow directly through the roof valley, leading to faster drainage and minimizing the risk of debris accumulation. Exposed valleys are typically found in regions with low precipitation or when cost considerations outweigh the need for additional protection.

There are several benefits and drawbacks to consider.


The primary advantage of exposed valleys is their cost-effectiveness. Since they require fewer materials and labor, they are generally more affordable to install than closed roof valleys. This can be particularly beneficial for homeowners on a budget or large-scale roofing projects where cost savings are a priority.

Additionally, open roof valleys provide better visibility, allowing homeowners and inspectors to easily detect potential issues, such as clogs or damage to the channel. With the seam exposed, it becomes easier to identify and address any problems that may arise, ensuring the longevity and functionality of the roof valley.

Exposed valleys can contribute to the overall aesthetics of a building. The exposed seam adds a distinct architectural element, creating visual interest and enhancing the overall design of the roof.


While open roof valleys offer cost savings and superior drainage, they are more prone to wear and tear. Exposed to the elements, open valleys are more susceptible to wind, debris, and UV radiation damage. Over time, this exposure can lead to accelerated deterioration and a shortened lifespan for the roofing materials in the valley area.

Open-roof valleys may not be the most suitable choice in areas with high precipitation or frequent severe weather conditions. The lack of a covering material leaves the joint area vulnerable to water penetration, increasing the risk of leaks and water damage. In such cases, closed roof valleys with additional protective layers may be a better option to ensure optimal waterproofing.

Furthermore, the exposed seam of open roof valleys may require more frequent maintenance and cleaning. Leaves, branches, and other debris can easily accumulate in the valley, potentially causing blockages and hindering proper water flow. Regular inspections and cleaning are necessary to prevent any issues and maintain the functionality of the roof valley.

Overall, open roof valleys offer a cost-effective and efficient solution for roof drainage in certain situations. However, it is important to consider the specific climate, budget, and maintenance requirements before deciding on the type of valley construction for a roofing project.


Closed Roof Valleys


In contrast to open roof valleys, closed roof valleys have an added layer of protection over the seam. Commonly referred to as closed-cut or woven valleys, this construction style overlaps the shingles or metal flashing to create a sealed channel.

This method can help prevent water penetration, making closed-roof valleys particularly suitable for areas with high precipitation or when enhanced water resistance is desired.


One of the crucial advantages of closed-roof valleys is their superior ability to resist water infiltration. The additional layer of protection ensures that water is directed away from vulnerable areas, reducing the risk of leaks and water damage to the underlying structure. Closed roof valleys also provide better insulation and overall structural stability.


Although closed-roof valleys offer enhanced protection, they are more expensive. The additional materials and labor required to create a closed valley contribute to the overall expense of the roofing project. Furthermore, the concealed nature of closed roof valleys can make it more challenging to identify and address any maintenance or repair issues that may arise.

Comparing Open and Closed Roof Valleys

Aesthetics: Open vs Closed

In terms of aesthetics, open roof valleys often lend a more traditional and rustic look to a roof. The exposed seam can add charm and character to certain architectural styles. On the other hand, closed roof valleys provide a more streamlined and modern appearance, as the additional layer of material creates a clean and uninterrupted surface.

Durability: Open vs Closed

Regarding durability, closed-roof valleys tend to outperform open-roof valleys. The added layer of protection in closed valleys offers increased resistance to wear and tear, protecting the roofing materials from weathering and potential damage.

Cost: Open vs Closed

Cost considerations often shape the decision between open and closed roof valleys. Open valleys are generally more affordable due to their simpler construction and reduced material requirements. In contrast, closed roof valleys involve additional labor and materials, resulting in higher installation costs. For more information on roof replacement costs, visit the Cost vs Value guide for 2023.

In Closing

Choosing between open and closed roof valleys ultimately depends on various factors, including climate, budget, architectural style, and personal preferences. Consulting with a roofing professional can help you make an informed decision and ensure that your chosen roof valley style provides optimal performance, aesthetics, and protection for your home.

Whether you’re looking for a high-quality roof installation, repair, or new gutters and siding, AIC is here to help. We believe in and practice the best customer service possible, including showing up on time, following through on what we say we’ll do, and treating people with common decency and respect.

Our in-home consultations are free, informative, and low-pressure. Please get in touch with us by texting, calling, or filling out our contact form.

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