Understanding Roof Valleys: Types, Benefits, and Best Installation Practices

Vlad Antoniuk
5 days ago
4 min read

A well-designed roof not only protects a home from external elements but also ensures proper water drainage. One of the most critical components of a sloped roofing system is the roof valley. These structural features channel rainwater and melting snow toward the gutters, preventing water buildup and potential leaks. Properly installed roof valleys enhance both the functionality and longevity of a roof.

What is a Roof Valley?

A roof valley is the internal angle where two sloped sections of a roof meet, forming a channel for water runoff. Valleys are designed to direct water toward the gutters, preventing pooling and damage to shingles. Without properly installed roof valleys, water can accumulate in low spots, leading to leaks, mold growth, and structural deterioration.

Roof valleys come in two main types: open valleys and closed valleys. The choice between these depends on factors such as climate, aesthetic preference, and roofing material.

Closed Valley Roof

A closed valley roof is a system where shingles completely cover the valley, creating a seamless look. Beneath the shingles, a waterproof underlayment or an additional ice and water shield is installed to prevent leaks.

Advantages of Closed Valley Roofs

Aesthetic appeal, as the valley blends with the rest of the roof
Protection from exposure to wind-driven rain and debris
Cost-effective compared to metal valley flashing

Challenges of Closed Valley Roofs

Higher risk of water infiltration if shingles are not installed correctly
Increased wear and tear due to water flow concentration
Regular maintenance required to clear debris buildup

Open Valley Roof

An open valley roof features an exposed valley lined with metal flashing, rubber membranes, or stone-coated steel. Instead of relying solely on shingles, this system provides an additional layer of waterproofing protection.

Benefits of Open Valley Roofs

Enhanced water drainage efficiency
Reduced wear on shingles in high-flow areas
Longer lifespan due to the durability of metal or rubber flashing
Suitable for regions with heavy rainfall or snowfall

Potential Drawbacks of Open Valley Roofs

Slightly higher installation costs due to additional materials
Visible flashing may not be preferred for some architectural styles

Roof Valley Flashing: A Critical Component

Flashing is an essential protective layer installed in roof valleys to prevent leaks. It is typically made of metal, rubber, or concrete. The choice of flashing material impacts both the durability and appearance of the roof.

Types of Roof Valley Flashing

Metal Valley Flashing

Metal flashing is the most commonly used material due to its durability and waterproofing properties.

Steel flashing: Affordable but requires a rust-resistant coating
Aluminum flashing: Lightweight and corrosion-resistant, ideal for coastal areas
Copper flashing: Premium option known for its long lifespan and attractive patina

Concrete Valley Flashing

Concrete flashing is mainly used on tile or slate roofs. It provides a rigid and durable solution but requires precise installation to prevent cracks.

Rubber Valley Flashing

Rubber flashing is highly flexible and resistant to extreme temperatures. It is particularly useful for dead valleys or complex roof structures. Modified bitumen membranes can be used to reinforce rubber flashing for added protection.

The Importance of Proper Roof Valley Installation

Correct installation of roof valleys is essential to prevent leaks, premature wear, and costly repairs. Key installation steps include:

Proper Underlayment – A waterproof membrane should be installed beneath the valley to provide an extra layer of protection.
Correct Flashing Placement – Metal, rubber, or concrete flashing should be securely fastened to prevent shifting.
Shingle Alignment – For closed valleys, shingles must be precisely cut and overlapped to avoid gaps.
Regular Maintenance – Keeping valleys clear of leaves and debris ensures proper water drainage.

Dead Valleys: A Hidden Roofing Concern

Dead valleys occur when multiple roof slopes converge into a flat or nearly flat surface, preventing proper water runoff. Without adequate flashing and drainage, dead valleys can become a major source of leaks and structural damage.

How to Address Dead Valleys

Install a high-quality waterproof membrane to prevent water pooling
Use a wider flashing material to improve water flow
Ensure a slight slope is created to direct water toward the gutters

Choosing the Best Roof Valley System

Selecting the right roof valley type depends on several factors, including climate, roof material, and budget.

For areas with heavy rain or snow: Open valleys with metal flashing are recommended for better drainage.
For homes with asphalt shingles: Closed valleys provide a more seamless look but require frequent maintenance.
For properties with slate or tile roofs: Concrete or metal flashing offers a durable and aesthetically pleasing solution.

Professional Roof Valley Installation Services

For homeowners seeking high-quality roof valley installation and repair, working with a certified contractor ensures lasting results. East Penn Roofing, located in Lehigh Valley, PA, has built a reputation for excellence in roofing services. The company holds industry-leading certifications, including:

OSHA Safety Certified
Atlas Pro Certified
Owens Corning Preferred Contractor
CertainTeed Shingle Select Contractor
Roofing Insights Preferred Contractor
GAF Certified Installer
Velux 5-Star Certified Contractor
SRCA Slate Roofing
HAAG Certified

Frequently Asked Questions

How long does roof valley flashing last?

Metal flashing can last 30-50 years, while rubber membranes typically last 20-30 years. Regular inspections help identify signs of wear early.

What is the best material for roof valley flashing?

Copper and aluminum are excellent choices due to their durability and corrosion resistance. For budget-friendly options, galvanized steel is commonly used.

Can roof valleys cause leaks?

Yes, improperly installed or damaged roof valleys are a leading cause of leaks. Regular maintenance and timely repairs prevent major issues.

How can I maintain my roof valleys?

Keep valleys clear of leaves and debris, inspect for cracks or rust, and schedule professional inspections every few years.

Should I choose an open or closed valley for my roof?

If you prioritize longevity and better drainage, an open valley is the best option. For a more seamless appearance, a closed valley works well but requires more upkeep.

Conclusion

Roof valleys play a crucial role in protecting a home from water damage. Choosing the right type of valley, ensuring proper flashing installation, and maintaining clear drainage paths are essential for long-lasting roof performance. Working with a certified roofing contractor ensures that roof valleys remain durable and efficient for years to come.

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