A Homeowner’s Guide To Roof Valleys & How To Shingle One

While many people know that asphalt shingles are one of the simplest roofing materials to install, regardless, there are parts of the roof that make installation a little more complex. The roof valley is one of these complex spots, due to its V-shaped design that is formed where two roof planes meet. 

In this blog post, we’ll explain what roof valleys are in greater detail, why they're essential for your home's health, and how to shingle them properly to prevent costly damage.

What Is A Roof Valley, And What Is Its Purpose?

A roof valley is a triangular section of a roof where two roof slopes meet, allowing water to run off the roof by forming a channel that directs the flow of water to the gutter.

To keep water from seeping into the roofing structure, the valley is typically lined with waterproofing material such as felt or a rubber membrane. Crucial for diverting water, a roof valley collects rainwater and snowmelt from the higher slopes of the roof, channeling it away to prevent pooling. This keeps the roof watertight and prevents damage to the underlying materials. 

What Are The Different Types Of Roof Valleys?

There are three main types of roof valleys:

1. Open-Cut Roof Valleys

An open roof valley features a visible gap between roofing materials on either side, with exposed flashing covering where the roof planes meet. This allows for efficient water and debris runoff and creates a clean, linear appearance.

Pros: 

• Effective water drainage
• Ideal for heavy rainfall areas
• Easy maintenance and inspection of the valley

Cons: 

• Higher initial installation costs compared to other valley types
• Potential risk of leaks if not installed properly
• Increased maintenance requirements over time

2. Closed-Cut Roof Valleys

In a closed roof valley design, shingles or roofing material extend from one side to cover the opposite side, ensuring a seamless appearance and added water protection. This method is often used with asphalt shingles, where overlapping shingles are trimmed and sealed for a secure finish

Pros 

• Aesthetic appeal with a clean, finished look
• Gives an extra layer of protection 
• Offers more shingle options and design flexibility.

Cons

• Generally more expensive to install compared to open valleys 
• Increased exposure to the elements due to the overlapping shingles
• Potential risk of leaks if not installed properly.

3. Woven Roof Valleys

A woven roof valley consists of shingles from both sides overlapping in a woven pattern, which improves durability and appearance over traditional valleys. This design provides additional water protection and is commonly used with asphalt shingles, which are carefully trimmed and interlocked to create a woven effect.

Pros

• Adds an extra layer of protection from all the elements.
• Offers increased durability and resilience
• Can be a visually appealing design choice.

Cons

• Generally more complex and time-consuming to install
• Resulting in much higher overall costs compared to other valley types.

Roof valleys can be made of metal (aluminum, copper, or galvanized steel), shingles (asphalt, slate, or synthetic), or even roll roofing material.

A Step-By-Step Guide On How To Shingle A Roof Valley

Step 1: Prepare The Valley

Begin by applying an underlayment material, such as ice and water protector, directly onto the roof deck. You can also add valley liners, such as a self-adhering membrane or rubberized asphalt, along the entire length of the valley. This layer acts as a barrier against water, preventing leaks and safeguarding the valley beneath the shingles.

Step 2: Install Roof Valley Flashing

Position Flashing: Place a strip of an ice and water protector membrane down the center of the valley. Each piece should overlap by at least 6 inches to form a continuous water barrier. Utilize nails to hold it in place temporarily, allowing for smooth adjustment after removing the backing.

Secure Flashing: Center metal flashing in the valley and secure it with nails along the edges. Ensure overlaps are at least 6 inches, and apply asphalt plastic cement beneath to create a tight seal against water penetration.

Step 3: Snap Chalk Lines

Mark Valley Lines: Snap two parallel chalk lines along the length of the valley. These lines should start at 8 centimeters wide, and increase by 1 centimeter as you move down towards the eaves . You’ll then want to trim the shingles so that they fit against your lines and seamlessly blend with the roof.

Step 4: Install Shingles

Begin Shingle Application: Start installing shingles on one roof face, extending them over the valley. 

Secure Shingles: Nail shingles at least two inches away from the chalk lines and embed them in asphalt plastic cement for a secure, water-resistant seal within the roof valley

Finish Installation: Trim shingles at the valley edge to align flush with surrounding shingles. Trim upper corners to direct water efficiently into the valley during heavy rainfall.

Step 5: Weaving or Interlocking the Valley Shingles

Unlike an open valley, where the flashing is installed, you can install a woven valley for enhanced protection. For this valley, asphalt shingles will be interlocked, or woven across the valley.

How Much Does It Cost To Repair Or Replace A Roof Valley?

Fixing or replacing a roof valley in Pittsburgh can cost different amounts. On average, repairing a roof valley costs between $300 and $1,000. If the damage is extreme and can't be repaired, replacing a roof valley can cost between $4,000 and $8,000, depending on the roof's size and the materials used.

Also Read: The Top Signs That Your Roof Valley Flashing Needs Attention

Maintenance Requirements For A Roof Valley

It is essential to take good care of your roof valley, so here are some tips to guide you in its maintenance:

Regular Cleaning and Debris Removal

1. Routinely Clear Debris: Regularly remove leaves and twigs to prevent blockages in the flow of water.
2. Inspect And Cleanse: Use a wire brush to clean and inspect for wear, like cracked sealant or rust.

Identifying and Fixing Problems

3. Spot Signs Of Wear: Address visible damage, such as cracks, rust, or sealant gaps, as soon as possible.
4. Repair Gaps and Cracks: Use corrosion-resistant materials for repairs. 
5. Replace Damaged Flashing: Replace severely corroded roof valley flashing with new, properly sealed flashing.

Regular Inspections

6. Frequent Checks: Inspect your roof valley twice a year and after severe weather.

Additional Tips

7. Select Durable Materials: Use metal like copper or galvanized steel for longevity.
8. Ensure Correct Installation: Proper installation and sealing are crucial.
9. Maintain Diligently: Regular upkeep prevents major issues.

Conclusion 

While this blog post may have made Installing shingles on a roof valley appear less complicated, the task is best left to professionals who have extensive experience handling this type of installation.

Trust McClellands Contracting and Roofing for expert installation and maintenance of roof valleys, ensuring durability and protection for your roof. Our quality roofing services minimize risks like water damage and costly repairs, offering tailored solutions you can depend on. Call us at (412) 353-5660 to speak with one of our experts.