Roof Valleys and Their Installation Process

A valley on a roof is a crucial architectural feature where two sections of the roof meet to form a V-shaped depression or channel. These valleys play a vital role in directing rainwater, snowmelt, and debris away from the roof’s surface, ensuring proper drainage and preventing water from pooling or infiltrating the structure. Roof valleys are particularly common in roofs with intersecting planes, such as gable roofs, hip roofs, or complex roof designs. Roofers employ specific techniques and materials to install valleys effectively, ensuring optimal performance and durability.

The installation process typically involves several steps to create a watertight seal and reinforce the structural integrity of the roof. In this post, we’ll guide you through the process of installing a roof valley, detailing the steps involved, best practices, and explaining why it’s crucial for your roofing project.

Step One: Setup and Centerline

To begin the installation of a roof valley, roofers first identify the location where the valley will be situated based on the roof’s design and layout. Once determined, they mark the valley’s centerline along the roof’s ridge, extending down to the eaves. This guideline serves as a reference point for accurately positioning and aligning the valley material.

Step Two: Removing Old Material

Next, roofers prepare the roof surface by removing any existing roofing materials or debris from the designated valley area. This step ensures a clean and level substrate for the installation of the valley material.

Roof Valley Installation - Removing Material

Step Three: Add Membrane and Flashing

The valley material used can vary depending on the roofing system and the preferences of the roofer. Common options include metal valley flashing, which is typically made from galvanized steel, aluminum, or copper, and specialized underlayment membranes designed specifically for valleys. These membranes include products like ice and water shield and SBS self-adhered base layers of rolled roofing. Membranes are more common in areas with large amounts of rain as they tend to leak less.

Step Four: Add Valley Materials

Once the valley material is selected, roofers carefully cut and shape it to fit the dimensions of the valley area, ensuring a precise and snug fit. They then position the valley material along the centerline marked earlier, overlapping it with the adjacent roofing materials on either side of the valley.

Step Five: Secure the Valley

To secure the valley material in place, roofers fasten it to the roof deck using nails, screws, or roofing adhesive, depending on the material and roof design. Special attention is paid to ensure that the valley material is securely attached and free from any gaps or loose edges that could compromise its effectiveness.

Step Six: Add Roofing Shingles & Sealers

Finally, roofers apply additional layers of roofing materials, such as asphalt shingles or roofing cement, over the valley area to further reinforce the seal and provide added protection against water infiltration. Care is taken to ensure that the roofing materials are properly overlapped and sealed to prevent water from penetrating the valley.

Roof Valley Installation

Notice an Issue with Your Roof Valley? A Good Roofer Can Help!

In conclusion, roof valleys are essential components of roofing systems designed to facilitate proper drainage and protect the structure from water damage. Through meticulous installation techniques and the use of quality materials, roofers ensure that valleys effectively channel water away from the roof’s surface, contributing to its longevity and performance. This is very important as one of the most common roof leak calls a roofing contractor gets is for failing roof valleys.

If your roof is leaking under a valley or you have any other concerns about your roof’s performance or condition, contact Roof MD to come do a comprehensive roof inspection to determine what work may need to be done to solve any problems.