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How to install step flashing

Updated: Aug 14, 2023

Installing step flashing is an important step in ensuring proper waterproofing and preventing water intrusion in areas where a roof intersects with a vertical surface, such as a chimney, wall, or dormer. Here's a general guide on how to install step flashing:

Step flashing installation can vary depending on the specific roofing material and the design of your structure. It's always recommended to consult the manufacturer's instructions and local building codes for specific guidelines.

Tools and Materials Needed:

- Step flashing (typically made of metal, such as lead or galvanized steel)

- Roofing nails or screws

- Roofing cement or sealant

- Pry bar or roofing shovel

- Hammer

- Tin snips or metal cutting shears

- Roofing underlayment (if needed)

- Safety goggles

- Work gloves

- Ladder

- Caulking gun (if using sealant)

Step 1: Prepare the Work Area

Ensure that you have a stable and safe working surface by using a ladder or scaffolding. Put on safety goggles and work gloves for protection.

Step 2: Remove Existing lead flashings

If necessary, lift the existing roofing material above the area where the step flashing will be installed. Use a pry bar or roofing shovel to carefully lift the lead flashings without causing damage. Take caution not to break or crack the lead flashings.

Step 3: Install Underlayment (if required)

If your roofing system requires an underlayment, such as a self-adhesive waterproofing membrane or roofing felt, apply it to the area where the step flashing will be installed. Ensure that it overlaps the lower course of underlayment by a few inches.

Step 4: Cut Step Flashing Pieces

Measure the length of the area where the step flashing will be installed. Cut the step flashing into individual pieces using tin snips or metal cutting shears. Each piece should be long enough to extend up the vertical surface and wide enough to cover the width of the shingle or roofing material.

Step 5: Install Step Flashing

Starting from the bottom, position the first piece of step flashing on the lower course of the vertical surface. Ensure that it is tucked under the upper course of roofing material and extends onto the roof deck. Attach the step flashing to the roof deck using roofing nails or screws, placing them in the upper corner of the flashing. Be careful not to overdrive the fasteners, as it may cause damage to the roofing material.

Step 6: Apply Roofing Cement or Sealant

Apply a thin bead of roofing cement or sealant along the exposed edges of the step flashing to provide additional waterproofing. Use a caulking gun for precise application.

Step 7: Continue with the Additional Step Flashing

Repeat the process of installing step flashing for each successive course, ensuring that each piece overlaps the one below it. The step flashing should extend up the vertical surface and be covered by the roofing material above it.

Step 8: Replace tiles or slate

Carefully reposition the lifted stiles/slate or roofing material back into place, ensuring that they are properly aligned and cover the step flashing. Secure them with roofing nails or screws as necessary.

Step 9: Inspect and Clean Up

Inspect the installed step flashing to ensure it is securely attached and properly sealed. Remove any debris or excess roofing cement from the work area.

Remember, this is a general guide, and the specific installation process may vary based on the roofing material

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