Roof Flashing Installation for Clay Tile Roofs: Mistakes to Avoid

The roof flashing installation process for clay tile roofs is critical for several reasons: maintaining the life of the roof surface, preventing water leakage, and preventing structural damage to the roof base and home interior. Learn here how to avoid the most common mistakes when installing roof flashing for clay tile roofs. Preventing these errors when you first install your clay tile roof will save you thousands of dollars in repairs later.

Mistake #1: Poor Quality Flashing Material

Using aluminum flashing may save you money in the beginning, but aluminum will not stand up to weather conditions as long as your clay tile does. Within a decade, your roof and its underlying supports will start to deteriorate under this low-grade flashing. You will spend more money to redo the entire roof flashing and make structural repairs, than you would have by initially buying sheet copper, soft copper, lead coated copper or galvanized steel containing up to 1-1/2 ounces of zinc per square foot.

Mistake #2: Too Low Roof Slope

Before installing the clay tile and flashing, check your roof's slope to ensure it is between 4-1/2 and 6-1/2. A low sloped roof of 3 or less will not allow effective water drainage, no matter how good the quality of the flashing materials.

Mistake #3: Inadequate Flashing Around a Chimney or Vent Pipe

Inadequate flashing around a chimney or vent pipe surrounded by clay tiles will damage the integrity of your chimney and may cause it to collapse. Install an aluminum sublayer around the chimney or vent, and have the flashing extend 6 inches up the sides of the chimney. Create a pan effect with the flashing, folding it to extend 2 inches under the clay tiles. To achieve this level of protection around a chimney, you will need metal flashing at least 9 inches wide. Add a counterflash as well, to conceal the overlap at the wall, minimizing water permeation.

Mistake #4: Too Narrow Valley Flashing

On roof areas where clay tiles slope upward and away from each other, don't skimp on valley flashing. Most municipal building codes require that the valley flashing extends 11 inches under the clay tile on each side from the center line of the valley. The upslope of the center valley must measure a minimum of 1 inch on each side. These valleys also channel debris such as conifer needles and leaves off the roof. In areas where the January temperatures are below 25 degrees F (-5C), correctly flashed valleys channel snow and ice buildup off the roof.

Mistake #5: Too Rigid Valley Flashing

Too-rigid valley flashing will twist and warp when cold precipitation freezes then melts. Do not nail down valley flashing so it is immobile. Valley flashing sections must be installed with cleats that allow for all temperature changes that bring about contraction and expansion of the flashing material.

Mistake #6: Insufficient Roof Terminal Tile to Cover the Flashing

Using insufficient layers of roof terminal tile such as ridge boards, hip tiles and hip roll tiles will damage the clay tile roof flashing. Water will get under the roof flashing, rendering the roof tiles unstable and subject to water damage.