Roof to Wall Flashings and Their Role in Preventing Roof Leaks

A roof valley is an essential architectural element where two sections of a roof converge, creating a V-shaped channel that efficiently directs water and debris away to ensure proper drainage. Commonly found in complex roof designs, valleys demand specific installation techniques to achieve optimal performance and longevity. Durable materials such as metal or specialized membranes are employed, alongside components like base and step flashings, to prevent water infiltration at the roof and wall junction, thereby safeguarding the structure from leaks and damage. In this post, we will discuss what flashings are, the different types available, and the importance of roof to wall flashings. Additionally, we will examine common issues and highlight what to avoid to help you recognize subpar workmanship.

Table of Contents

1. What is Flashing?
2. What Kind of Flashing Are There?
3. What is a Roof to Wall Flashing?
4. What Type of Materials?
5. What About Sizing?
6. Should There Be a Gap?
7. Do you Need Sealant?
8. Common Issues
10. Can You Re-use Old Roof Flashing?

What is Flashing?

Flashing refers to the thin, waterproof materials installed on roofs and walls that protect against water infiltration. These components are typically made from metal (aluminum or copper), specialized membranes (like EPDM rubber or PVC), or a combination of both. They are designed to direct rainwater away from vulnerable areas where water can seep into the building structure

What Kind of Flashing Are There?

There are several types of flashing used in roofing, depending on the specific needs and design of a structure. These include:

• Continuous: Also known as “apron flashing,” it’s a long metal piece that directs water down to the shingles. Long pieces can break or warp due to seasonal expansion and contraction, so they include built-in expansion joints for flexibility.
• Skylight: Some skylight manufacturers provide flashing, but roofers may need to create or buy it separately.
• Valley: Open valleys have metal flashing to protect this critical roof area.
• Kickout: Bridges the gap between where step flashing ends and the gutter begins, directing water into the gutter.
• Drip edge: Roofing professionals often cut flashing from sheet metal with snips to fit precisely. Be cautious buying premade flashing; some are not suitable for roofs and may break if used improperly. For example, head flashing protects doors and windows from water.

What is a Roof to Wall Flashing?

Effective water management in building construction relies on directing water away from structures using drainage systems and proper flashing. Flashing, especially at roof-wall intersections, prevents water intrusion. Step flashing is used for shingle roofs, while continuous flashing suits metal or rubber membrane roofs. Key elements include corrosion-resistant materials and kick-out to guide water into gutters. Roof to wall flashings are speficically made up of three distinct components:

• Base flashing: Roof features like chimneys need two pieces of flashing to ensure rain is directed downward. It’s challenging to install around a chimney, but two-part flashing allows for movement with weather changes, keeping the system secure. The base flashing is the bottom piece.
• Step flashing: A rectangular piece bent 90 degrees, used for roof-to-wall flashing. Installed in layers with shingles to direct water away from the wall.
• Counter-flashing: Placed above or opposite base flashing, it completes the two-part system.

What Type of Materials?

There are several types of materials that can be used for roof to wall flashings, including aluminum, copper, stainless steel, and even PVC or rubber membrane. The choice of material often depends on factors such as climate, budget, and aesthetic preferences. Roofing professionals now prefer aluminum, copper, and steel instead of traditional lead materials. Aluminum is lightweight and easy to form but needs coating to prevent degradation. Copper is durable and malleable but may develop a patina. Steel is the most common choice due to its malleability and corrosion resistance. Building codes often specify required materials and thickness, like 26-gauge galvanized steel. Always check local building codes to ensure compliance.

What About Sizing?

As with any roofing component, proper sizing is crucial for optimal performance. The width of the base flashing should be at least 4 inches wider than the step flashing to provide adequate coverage and prevent water from seeping in between the two pieces. Additionally, the length of the step flashing should extend at least 8 inches up the wall and overlap with each piece by at least 2 inches to create a continuous barrier against water.

Should There Be a Gap?

No, there should not be a gap in the flashing. They are meant to create a continuous barrier against water. Any gaps or breaks in the flashing can compromise its effectiveness and lead to water infiltration. Proper installation is key to ensuring there are no gaps and that all seams are sealed tightly to prevent leaks. If you notice any damages or gaps, it is essential to have them repaired as soon as possible to avoid potential damage to your roof and structure.

Do you Need Sealant?

Sealant or caulking should never be used as a replacement for flashing. While it may seem like an easier and quicker solution, sealant can degrade over time and will eventually fail, leading to potential water intrusion and damage. Flashing is specifically designed to properly direct water away from critical areas of the roof, while sealant is not meant for this purpose. It is always best to invest in proper installation to avoid costly repairs and potential structural damage.

Common Issues

Roof-to-wall flashings are essential for preventing leaks, serving as a barrier that directs water away from vulnerable areas where the roof meets the walls. However, improper installation or deterioration over time can lead to leaks. Here is a brief list of the most common issues we encounter with roof to wall flashings:

• Improper installation practices, such as failing to adequately overlap or secure flashings to the roof and wall, can create gaps, cracks, or separations that allow water to penetrate the structure.
• Inadequate flashing design or the use of materials incompatible with the roof and wall can contribute to leaks.
• Flashings that are too small or improperly shaped may not provide sufficient coverage or protection.
• Using low-quality materials or neglecting to maintain flashings can lead to deterioration, corrosion, or eventual failure.
• Insufficient slope or drainage at the roof-to-wall junction can cause water to pool, placing extra stress on the flashings and increasing the likelihood of leaks.
• Incorrectly installed siding, brick, or stucco can also result in non-roof-related leaks.

Can You Re-use Old Roof Flashing?

When re-roofing, it’s wise to replace all flashing, as older flashing may fail before the new roof, leading to potential leaks or damage. Flashing is a crucial component in preventing water penetration, directing water away from joints and seams. Only one layer should be present on a roof to ensure its effectiveness. It’s important to remember that flashing should never be reused, although some cost-cutting roofers attempt to do so to save on repair or replacement expenses, compromising the integrity of the roofing system. Investing in new flashing can prevent future issues and extend the lifespan of the new roof.

What’s next?

Roof to wall flashings are crucial components of roofing systems that play a vital role in preventing water intrusion and roof leaks at the junction where the roof meets the wall. However, they can themselves be sources of leaks if not installed correctly, if they deteriorate over time, or if there are design or construction flaws. Regular inspection, maintenance, and timely repairs are essential to ensure their effectiveness and preserve the integrity of the roof system.

Working with qualified roofing professionals and using high-quality materials can help mitigate the risk of leaks and ensure long-term performance and durability. If you need the assistance of a quality roofing contractor like Roof MD, contact us today for a free roof inspection.