Open vs. Closed Valley Roof: Choosing the Best Roof Valley System

Roof valleys play a critical role in a home’s drainage system, directing rainwater and melting snow safely toward the gutters. The choice between an open and closed valley roof impacts both the longevity and performance of a roofing system. Each option has advantages and drawbacks, making it essential for homeowners to understand the differences before making a decision.

What Is a Roof Valley?

A roof valley is the intersection where two sloped sections of a roof meet. This area naturally channels water toward the gutters, preventing water buildup that could lead to leaks, mold growth, and structural damage. Properly installed valleys enhance a roof’s efficiency by ensuring smooth water runoff.

There are two primary types of roof valleys: open valleys and closed valleys. Each system offers unique benefits and challenges, making the choice dependent on climate, budget, and aesthetic preferences.

Closed Valley Roof

A closed valley roof uses shingles to cover the valley, concealing the underlying waterproofing material. The shingles are arranged in a way that directs water over the valley and toward the gutters. This method offers a seamless and uniform appearance.

Advantages of Closed Valley Roofs

• Cost-Effective InstallationClosed valley roofs are generally more affordable because they do not require additional flashing materials such as metal or rubber.

• Uniform AppearanceBecause the valley is covered with shingles, it blends seamlessly with the rest of the roof, creating a smooth and cohesive look.

Disadvantages of Closed Valley Roofs

• Higher Maintenance RequirementsWithout metal flashing, shingles in the valley experience accelerated wear due to water runoff and debris buildup, leading to more frequent maintenance.

• Increased Risk of LeaksWater consistently flows over the shingles, eroding the protective granules and making the valley vulnerable to leaks, especially in areas with heavy rainfall.

• Shorter LifespanThe lack of additional waterproofing materials means shingles in the valley deteriorate faster, requiring replacement more frequently than those on an open valley system.

Open Valley Roof

An open valley roof features exposed flashing made of metal, rubber, or concrete that channels water off the roof. Unlike a closed valley, the flashing is visible, creating a distinct separation between the roofing materials.

Advantages of Open Valley Roofs

• Superior Water DrainageThe metal or rubber flashing provides a smooth path for water runoff, reducing the risk of leaks and pooling.

• Extended Roof LongevityBecause water flows directly over the flashing rather than the shingles, the surrounding roofing material experiences less wear, extending the life of the roof.

• Enhanced Protection Against Weather ElementsOpen valleys are particularly beneficial in regions with heavy rainfall or snowfall, as they minimize water damage and improve overall durability.

Disadvantages of Open Valley Roofs

• Higher Initial CostThe addition of flashing materials increases the upfront cost compared to a closed valley system. However, the long-term benefits often outweigh the initial investment.

• Visible Flashing May Not Suit All Home StylesSome homeowners prefer the seamless look of a closed valley, as open valleys create a more pronounced contrast between the flashing and the shingles.

Roof Valley Flashing Materials

The choice of flashing material significantly impacts the durability and effectiveness of an open valley roof.

Metal Valley Flashing

• Aluminum: Lightweight and corrosion-resistant, making it ideal for coastal regions.

• Copper: A high-end option with superior durability and aesthetic appeal, lasting over 50 years.

• Steel: Often coated with zinc or aluminum to prevent rust, offering a cost-effective alternative to copper.

Concrete Valley Flashing

Used primarily with tile or slate roofs, concrete flashing provides a sturdy and long-lasting solution. However, it requires expert installation to prevent cracks.

Rubber Valley Flashing

A flexible and waterproof option, rubber flashing is often used in dead valleys or complex roof designs where traditional materials may not be suitable.

Open vs. Closed Valley Roof: Which Is Right for Your Home?

Climate Considerations

• In areas with heavy rainfall, strong winds, or snow, open valleys provide better drainage and durability.

• In milder climates with less precipitation, closed valleys may offer sufficient protection while maintaining a uniform aesthetic.

Aesthetic Preferences

• Homeowners who prefer a seamless roof design may opt for a closed valley.

• Those who appreciate contrasting details or have a modern home style may prefer the distinct appearance of an open valley with metal flashing.

Long-Term Maintenance and Costs

• Open valleys have a higher upfront cost but lower long-term maintenance expenses due to their superior durability.

• Closed valleys require more frequent inspections and potential repairs, increasing long-term costs.

Step-by-Step Roof Valley Installation

1. Assess the Roof’s StructureIdentify the best valley system based on roof slope, material, and local weather conditions.

2. Prepare the UnderlaymentApply a waterproof membrane beneath the valley to prevent leaks.

3. Install Flashing (for Open Valleys)Secure metal, rubber, or concrete flashing to guide water off the roof efficiently.

4. Lay the Shingles (for Closed Valleys)Arrange shingles to overlap in a pattern that directs water down the valley.

5. Seal the EdgesUse roofing cement or adhesive to reinforce the valley and prevent water infiltration.

6. Inspect and MaintainRegularly clear debris from valleys and check for signs of wear or damage.

Professional Roof Valley Installation Services

Choosing an experienced roofing contractor ensures that your roof valley system is installed correctly and built to last. East Penn Roofing, located in Lehigh Valley, PA, is a leading provider of high-quality roofing services. The company holds certifications from:

• 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 a roof valley last?

With proper installation and maintenance, metal flashing in an open valley can last 30-50 years. Closed valley shingles may need replacement every 15-25 years.

Which is more expensive: open or closed valley roofing?

Open valley roofing typically costs more upfront due to additional flashing materials, but it requires less maintenance and has a longer lifespan.

Can I switch from a closed valley to an open valley?

Yes, a roofing contractor can retrofit an existing closed valley by removing the shingles and installing flashing for better water management.

Do roof valleys need regular maintenance?

Yes, both open and closed valleys should be inspected periodically to remove debris and check for signs of wear, leaks, or rust.

What is the best material for roof valley flashing?

Copper offers the longest lifespan and best aesthetics, while aluminum is a more budget-friendly, corrosion-resistant alternative.

Conclusion

The choice between an open and closed valley roof depends on factors such as climate, aesthetics, and long-term maintenance. Open valleys provide superior water drainage and longevity, making them ideal for areas with heavy precipitation. Closed valleys offer a seamless appearance but require more upkeep. Consulting with a professional ensures that your home receives the best valley system for optimal performance and durability.

Read also our blog: Understanding Roof Valleys: Types, Benefits, and Best Installation Practices