Understanding Different Valley Types with Shingles: A Complete Guide
When it comes to roofing, one of the most critical yet often overlooked components is the roof valley. Roof valleys are the internal angles formed where two roof slopes meet, creating a channel that directs rainwater and snowmelt off your roof and into the gutters. Because valleys collect a lot of water and debris, their design and construction quality are vital to the long-term durability of your roof.
For homeowners considering or maintaining a shingle roof, understanding the different valley types can help prevent leaks, improve aesthetics, and increase the overall lifespan of your roofing system.
In this guide, we’ll explore:
- What roof valleys are and why they matter
- The common types of roof valleys used with shingles
- Advantages and disadvantages of each valley type
- Installation best practices
- Maintenance tips to extend your valley’s life
- How professional roofing companies handle valley installation and repair
What is a Roof Valley?
A roof valley is the V-shaped junction where two sloping roof planes intersect. Roof valleys are essential because they channel water off the roof, preventing pooling and leaks. They experience more water flow than other roof areas and can accumulate debris, making them vulnerable to damage.
Valleys are particularly important for asphalt shingle roofs because the overlapping nature of shingles and the valley flashing must work together perfectly to keep water out.
Why Valleys Matter in Shingle Roofing
- Water management: Properly designed valleys prevent leaks and water damage.
- Structural integrity: Valleys help manage roof load by guiding water and debris off the roof.
- Aesthetics: Neatly installed valleys enhance the roof’s appearance.
- Longevity: Poor valley design or installation is a leading cause of shingle roof failure.
Common Valley Types with Shingles
There are three primary valley types used in shingle roofing:
- Open Valley (Open Metal Valley)
- Closed Cut Valley
- Woven Valley
Each style has unique features, installation methods, pros, and cons.
1. Open Valley (Open Metal Valley)
What It Is:
The open valley features exposed metal flashing installed along the valley line, with shingles on each roof slope cut back to the edge of the metal. This creates a clean, visible metal strip down the valley.
How It’s Installed:
- A metal valley flashing (usually aluminum, galvanized steel, or copper) is laid directly on the roof deck along the valley.
- The metal extends past the valley line onto the roof planes.
- Shingles from each side are cut straight along the metal edge and laid to meet the flashing.
- The exposed metal is visible and provides a durable, waterproof channel.
Advantages:
- Highly durable and long-lasting due to metal flashing.
- Effective water shedding—metal resists rot and corrosion.
- Clean, modern aesthetic with visible metal flashings.
- Easy to inspect for damage or wear.
Disadvantages:
- Requires precise cutting and installation skill.
- Exposed metal may expand and contract causing noise.
- Visible metal may not suit all architectural styles.
2. Closed Cut Valley
What It Is:
In a closed cut valley, shingles from the upper roof slope are cut back along the valley line, but instead of exposing metal, the shingles from the lower slope are laid over the valley, covering the upper shingles and valley flashing.
How It’s Installed:
- Metal valley flashing is installed underneath the shingles, extending along the valley.
- Shingles on the upper slope are trimmed a few inches from the valley line.
- Shingles on the lower slope extend over the valley and the trimmed shingles.
- The valley metal is hidden beneath the overlapping shingles.
Advantages:
- More traditional appearance with shingles covering the valley.
- Improved aesthetics—no exposed metal.
- Easier to install than open valleys for some roofers.
- Good waterproofing when properly installed.
Disadvantages:
- Vulnerable to shingle cracking or splitting in the valley.
- Potential for water intrusion if shingles are not correctly layered.
- Repair can be more complicated since metal is hidden.
3. Woven Valley
What It Is:
The woven valley interlaces shingles from both slopes, weaving them together without exposing metal flashing. This technique creates a tightly interlocked pattern.
How It’s Installed:
- No valley flashing is exposed.
- Shingles from both roof slopes are alternately overlapped, “woven” into the valley.
- Installation requires precise nailing and shingle placement to maintain waterproofing.
Advantages:
- Visually seamless valley with no metal exposed.
- Can be installed with fewer materials.
- Classic appearance for traditional homes.
Disadvantages:
- Risk of leaks if shingles are improperly woven.
- Less durable in heavy rainfall or snow regions.
- Difficult to repair or replace shingles without disturbing the weave.
Comparing Valley Types: Which is Best for Shingle Roofs?
| Valley Type | Durability | Water Protection | Appearance | Installation Difficulty | Cost |
|---|---|---|---|---|---|
| Open Valley | High | Excellent | Modern, clean | Moderate to High | Moderate |
| Closed Cut Valley | Moderate | Good | Traditional | Moderate | Low-Moderate |
| Woven Valley | Low-Moderate | Moderate | Seamless, classic | High | Low |
Which One Should You Choose?
- Open Valley: Best for durability and heavy rainfall climates. Requires skilled installation but offers excellent protection.
- Closed Cut Valley: Popular for balanced aesthetics and protection, especially in residential roofs.
- Woven Valley: Suitable for mild climates with less water flow; best avoided in areas with heavy precipitation.
How to Install Roof Valleys with Shingles: Best Practices
Regardless of valley type, certain principles apply to shingle valley installation:
1. Use Quality Underlayment and Flashing
- Install a durable ice and water shield or waterproof underlayment in the valley area.
- Use corrosion-resistant metal flashing for open and closed cut valleys.
2. Proper Shingle Cutting and Placement
- Use a sharp roofing knife or tin snips for clean, straight cuts.
- Avoid overcutting or irregular edges.
- Maintain appropriate overlaps to prevent water intrusion.
3. Nail Correctly
- Use roofing nails of proper length.
- Avoid nailing in areas where water flows directly.
- Ensure nails secure shingles without damaging flashing or underlayment.
4. Slope and Drainage
- Make sure valleys have proper slope for water runoff.
- Clear debris regularly to prevent blockage.
5. Professional Installation
- Valleys are critical points; improper installation leads to leaks.
- Hire experienced roofing contractors knowledgeable in valley work.
Maintaining Your Roof Valleys
Roof valleys are high-traffic zones for water and debris. Here’s how to keep them functioning well:
- Regular Inspections: Check valleys for damaged or curled shingles, rusted flashing, or debris buildup.
- Clean Debris: Remove leaves, twigs, and dirt to prevent water pooling.
- Repair Damage Quickly: Replace cracked shingles or reseal flashing as soon as issues arise.
- Watch for Moss or Algae: These can hold moisture and cause damage.
- Gutter Maintenance: Keep gutters clean to avoid overflow affecting valleys.
Common Valley Problems and How to Fix Them
Problem 1: Leaks in Roof Valley
Cause: Improper installation, damaged shingles, cracked flashing, or clogged debris.
Fix:
- Inspect for damaged shingles or flashing.
- Replace or repair flashing as needed.
- Clean debris and improve drainage.
- Consider resealing flashing joints.
Problem 2: Cracked or Split Shingles in Valley
Cause: Natural wear, poor installation, or thermal expansion.
Fix:
- Replace affected shingles.
- Use flexible sealants to prevent water infiltration.
- Ensure proper nailing to avoid stress points.
Problem 3: Rusted Metal Flashing (Open Valleys)
Cause: Age and exposure to moisture.
Fix:
- Remove rusted flashing.
- Replace with corrosion-resistant materials.
- Paint or coat flashing to extend life.
How Roof Poole Ensures Perfect Valley Installation Every Time
At Roof Poole, we understand that the valley is one of the most vulnerable parts of your roof. Our expert team:
- Uses premium materials and industry best practices.
- Employs precise cutting and nailing techniques for lasting performance.
- Performs thorough inspections and tests after installation.
- Offers maintenance and repair services to extend your roof’s lifespan.
Frequently Asked Questions About Roof Valleys and Shingles
Q1: How long do roof valleys last?
A well-installed valley with quality materials can last as long as the roof, typically 20–30 years or more.
Q2: Can I install shingles over existing valley flashing?
Yes, but the flashing must be in good condition and correctly layered under the shingles.
Q3: Which valley type is best for heavy snow areas?
Open valleys with metal flashing are best as they resist ice dams and water pooling.
Q4: How much does valley installation cost?
Costs vary by valley type and roof size, but valleys typically add 5-15% to roofing costs.
Q5: Can I DIY valley installation?
Due to complexity and water protection needs, it’s best to hire a professional roofer.
Final Thoughts
Roof valleys are critical to your home’s defense against water damage. Choosing the right valley type and ensuring expert installation with quality shingles can protect your roof and home for decades.
If you’re considering a new shingle roof or need valley repair in the Poole area, trust Roof Poole to deliver expert craftsmanship, superior materials, and lasting protection.
Contact Roof Poole today for a free roofing consultation and keep your roof valleys—and your entire roof—in perfect condition.