How to Flash a Clad Window Brick Veneer Sill

When it comes to architectural aesthetics, few features can enhance the visual appeal of a building quite like a brick veneer sill on a clad window. This design element offers a touch of elegance and sophistication to any structure, whether it's a residential home or a commercial property. However, to ensure the longevity and durability of this beautiful feature, proper installation techniques are crucial. One essential step in the installation process is flashing, which is the process of installing a waterproof barrier to protect the window and underlying structure from moisture infiltration. In this guide, we will explore the step-by-step process of flashing a clad window brick veneer sill, ensuring that the installation isn’t only visually appealing but also fully functional for years to come.

How Should a Window Be Flashed?

Proper window flashing is crucial in preventing water infiltration and maintaining the integrity of a buildings envelope. To install window flashing correctly, a systematic approach should be followed. The process usually starts with cutting back the weather resistive barrier (WRB) around the rough opening, ensuring a clean and smooth surface.

Next, the sill pan flashing is installed. This flashing is placed on the bottom of the rough opening and acts as a slope to redirect any water that may penetrate the window. The sill pan flashing should fit tightly and be securely fastened to ensure optimal performance.

Next, sealant should be applied to further enhance the water-resistant properties of the window assembly. This sealant acts as an additional barrier, filling gaps and preventing any moisture from seeping in.

With the preparations complete, the window unit can be installed. It should fit snugly into the rough opening, ensuring a proper alignment and a tight seal against the flashing and WRB.

Finally, insulation should be applied around the window unit to further enhance energy efficiency and thermal performance. Insulating foam or fiberglass insulation can be used to fill any gaps and provide a thermal barrier.

Proper window flashing involves a systematic installation process that starts with cutting back the WRB, installing the sill pan flashing, securing the side WRB panels, applying sealant, installing the window unit, and finally, insulating around the window.

Flashing plays a crucial role in preventing moisture intrusion and condensation damage. It’s essential to install proper flashing when windows are situated in vulnerable areas, such as exterior walls, skylights, dormers, decks with screened-in porches, or any sections susceptible to rain or snow exposure.

Is Window Sill Flashing Necessary?

Window sill flashing is necessary for a variety of reasons. Firstly, it helps to prevent moisture from infiltrating the building. When windows are installed in exterior walls, there’s always a risk of rain, snow, or condensation seeping into the structure through the window frames and sills. Flashing acts as a barrier, diverting water away from vulnerable areas and ensuring that moisture doesn’t penetrate the building envelope.

If moisture is allowed to seep into the building, it can lead to structural problems such as rotting wood, corrosion of metal components, and the growth of mold and mildew. These issues can compromise the integrity of the building and pose health risks to occupants.

Improperly sealed windows can allow air leaks, causing drafts and increased energy consumption. Flashing helps to create an airtight seal around the window, minimizing air leaks and reducing heat loss or gain. This not only improves the comfort level inside the building but also helps to lower energy bills by reducing the need for heating or cooling systems to compensate for temperature fluctuations.

In addition, flashing is crucial for maintaining the overall durability and longevity of the building. Incorporating flashing into the window installation process ensures that the building remains structurally sound and maintains it’s aesthetic appeal for years to come.

These areas are particularly susceptible to water infiltration, given their exposure to the elements.

The Different Types of Window Sill Flashing Materials Available and Their Pros and Cons.

  • Aluminum flashing: lightweight and durable, but can corrode over time
  • Copper flashing: highly resistant to corrosion, but more expensive
  • Vinyl flashing: affordable and easy to install, but less durable than metal options
  • Lead-coated flashing: provides excellent protection and long lifespan, but has potential health risks
  • Galvanized steel flashing: strong and economical, but prone to rusting
  • PVC flashing: resistant to corrosion and affordable, but not as strong as metal options
  • Fiberglass flashing: lightweight and resistant to rust, but not as commonly used as other materials


By carefully following the proper techniques, such as correctly cutting and fitting the flashing, sealing and integrating it with the surrounding materials, and appropriately overlapping and securing the various layers, homeowners and professionals can effectively prevent water infiltration and potential damage to the structure. Additionally, ensuring that the flashing is adequately aligned and sloped to promote proper water drainage is crucial.

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