Step flashing is a critical component of a roofing system, specifically designed to protect areas where a sloped roof meets vertical walls. It ensures water is directed away from these vulnerable joints, preventing leaks and prolonging the lifespan of the roof.
What is Step Flashing?
Step flashing is a series of small, rectangular metal pieces installed in a “stepped” pattern alongside shingles where the roof meets a vertical surface, such as a chimney or wall. Each piece overlaps the one below it, creating a continuous barrier that redirects water away from the roof-wall junction.
Why Step Flashing is Important
Without step flashing, water can seep into the gap between the roof and the wall, leading to:
- Leaks: Water penetration can cause interior damage, including stained ceilings and walls.
- Rot and Mold: Prolonged moisture exposure may deteriorate roof decking and support structures.
- Compromised Insulation: Water infiltration can reduce the effectiveness of attic insulation, increasing energy costs.
Materials Used for Step Flashing
Step flashing is commonly made from durable materials that can withstand the elements, including:
- Galvanized Steel: A cost-effective and rust-resistant option.
- Aluminum: Lightweight and easy to install, though less durable in coastal areas.
- Copper: A premium material known for its longevity and aesthetic appeal, often used on high-end roofs.
How Step Flashing Works
Step flashing is installed in conjunction with shingles to create a watertight seal. Each piece is placed under a shingle and against the vertical surface, with the next shingle layer covering the top of the flashing. This overlapping pattern ensures water flows harmlessly down the roof, away from the joint.
Installation Process
- Preparation: The wall or chimney surface is cleaned and prepared for flashing installation.
- First Flashing Piece: The bottom piece is installed, overlapping the starter strip or first shingle.
- Layering with Shingles: Each piece of step flashing is placed over the preceding shingle course, creating a staircase-like pattern up the slope.
- Securing Flashing: Flashing pieces are nailed securely to the roof deck, not to the wall, allowing the roof and wall to expand and contract independently.
- Integration with Counter Flashing: For added protection, counter flashing may be installed over the step flashing on the vertical surface.
Common Problems with Step Flashing
- Improper Installation: Flashing not correctly layered with shingles can lead to water pooling and leaks.
- Corrosion or Damage: Over time, metal flashing may corrode or warp, reducing its effectiveness.
- Missing Pieces: Severe weather or poor installation can cause flashing to dislodge.
Maintenance and Repair Tips
- Inspect Regularly: Check for signs of rust, corrosion, or loose flashing during routine roof inspections.
- Clean Debris: Remove leaves and debris that can block water flow along the flashing.
- Repair Promptly: Replace missing or damaged flashing as soon as possible to avoid further issues.
- Seal Gaps: Apply waterproof sealant to small gaps or seams as a temporary fix until repairs can be made.
Step Flashing and Roof Longevity
Step flashing plays an essential role in preventing water damage at roof-wall intersections. Its overlapping design ensures a secure and effective barrier against leaks, making it a key feature of any properly installed roofing system.
By understanding step flashing’s purpose and maintenance needs, homeowners and professionals can ensure this vital component performs effectively for the life of the roof.