Kickout Flashing On Roof: Installation, Benefits, And Essential Maintenance Tips

Proper roof flashing is crucial for protecting American homes against water damage, and kickout flashing on roof installations is among the most important, yet overlooked, details. This comprehensive guide explores what kickout flashing is, why it matters, how to install it, common mistakes to avoid, and maintenance insights for homeowners and contractors.

What Is Kickout Flashing?

Kickout flashing is a specially shaped piece of metal or plastic installed where a roof slope meets a vertical wall. Its design directs rainwater away from the wall and into the gutter, preventing water infiltration behind siding, stucco, or brick, which can cause major structural issues over time.

Kickout Flashing Vs. Standard Flashing

Unlike standard step or continuous flashing, which simply keeps water moving down the side of a wall, kickout flashing projects outward to “kick” water into the gutter. This prevents water from running down the exterior wall, reducing the risk of moisture intrusion and costly damage to the home’s envelope.

Why Kickout Flashing Is Critical

Without proper kickout flashing, water carried down a roof can bypass the gutter, penetrating the wall assembly. Over years, this can lead to:

• Rotting sheathing, studs, or wall plates
• Mold growth behind siding, roofing, or even interior drywall
• Damage to insulation and decrease in energy efficiency
• Expensive repairs or the need for siding replacement

Key Locations For Kickout Flashing On A Roof

Kickout flashing is typically needed wherever a sloped roof eave terminates against a side wall. Common locations include:

• Bottom of roof-to-wall intersections, especially above doors or windows
• Where an attached garage roof meets the main wall
• At end points of step flashing runs adjacent to gutter systems
• Any complex roof profiles with intersecting valleys or dormers

Common Building Codes And Requirements

Many U.S. building codes now require kickout flashing in roof-to-wall transition areas. The International Residential Code (IRC), adopted across most U.S. regions, specifies that “diverter” or kickout flashing must be installed at the lower end of roof-to-wall intersections to guide water into the gutter system. Failing to meet these codes can result in rejected home inspections and increased liability for builders and roofing professionals.

Materials Used For Kickout Flashing

Kickout flashing is available in several durable materials, each with its pros and cons:

Material	Strengths	Potential Drawbacks
Galvanized Steel	Strong, widely available, affordable	Susceptible to rust if coating is damaged
Aluminum	Lightweight, rust-resistant, flexible	Can be dented, prone to corrosion with dissimilar metals
Copper	Very durable, attractive, corrosion-resistant	Higher cost, may stain siding as it ages
Plastic/Polymer	Corrosion-proof, easy to form, cost-effective	UV degradation, less durable under impact

Correct Kickout Flashing Installation: Step-By-Step

Proper kickout flashing installation ensures long-term protection and code compliance. Follow these steps for best results:

1. Gather The Right Materials And Tools

• Preformed kickout flashing (metal or plastic)
• Step flashing (for overlapping above the kickout piece)
• Roofing nails or screws (galvanized or stainless steel)
• Quality roofing sealant or caulk
• Snips, hammer, pry bar, utility knife

2. Prepare The Roof Area

Remove any siding or roofing materials as necessary to access the sheathing and ensure a weather-tight installation. Clean and inspect the area for existing water damage.

3. Install The Kickout Flashing

• Position the flashing at the lower (down-roof) end of the roof-to-wall joint, projecting outward above the gutter.
• Fasten through the flange into the wall sheathing and roof decking.
• Ensure the opening of the flashing extends past the siding, allowing free drainage.

4. Overlap With Step Flashing

Step flashing pieces must overlap the kickout flashing, channeling water away from the wall. Each successive piece should shingle over the one below, maintaining an uninterrupted waterproof barrier.

5. Replace Siding Or Finish Materials

Reinstall siding, making sure it covers the vertical leg of the flashing but does not block the kickout outlet. Caulk as needed, but do not seal the open end—water must be able to exit freely.

Common Kickout Flashing Installation Mistakes

Even professional roofers sometimes overlook kickout flashing details. Common mistakes include:

• Improper placement so the flashing doesn’t extend far enough past the wall
• Not integrating step flashing above the kickout, creating water entry points
• Using flat flashing bent by hand (often lacks sufficient projection for effective water diversion)
• Obstructing the end of the kickout with caulk or siding, trapping water
• Omitting the flashing entirely at critical transitions

Kickout Flashing And Different Siding Types

Proper integration differs depending on siding material:

• Vinyl Siding: The kickout should pass behind the initial course, with J-channel or trim ensuring a neat finish.
• Fiber Cement/Hardie Board: Maintain clearances per manufacturer guidelines, and do not caulk the open end.
• Stucco: A weep screed may be installed above the kickout for drainage; ensure proper lath and paper overlap.
• Brick: Allow a minimum 1-inch gap for water to exit, and integrate with through-wall flashing if present.

Signs Of Kickout Flashing Failure Or Absence

Homeowners should routinely inspect for warning signs near roof-to-wall interfaces, such as:

• Water stains or streaks on siding below roof eaves
• Bubbling or peeling paint in localized areas
• Visible rot, mildew, or dampness inside adjacent walls
• Moss, algae, or mold growth at roof edges
• Structural or finish trim deterioration at corners

Addressing these issues quickly can prevent more costly repairs later.

Kickout Flashing Maintenance Tips

Regular maintenance of kickout flashing can significantly extend its lifespan and the overall health of the home.

• Conduct visual inspections every spring and after major storms, looking for blockages or damaged flashing
• Clear leaves and debris from gutters and flashing outlets to maintain free water flow
• Check for loose fasteners, missing caulk, or separated joints
• Replace damaged or corroded flashing immediately—temporary repairs are often ineffective
• Trim back overhanging branches to reduce debris accumulation

Cost Considerations: Installation Or Retrofit

Kickout flashing is relatively inexpensive—but the cost to ignore it is much higher. Here’s what U.S. homeowners can expect:

Scenario	Estimated Cost (2025)	Notes
New Construction	$10–$25 per location	Minimal labor, easy access
Retrofit/Repair	$150–$600 per location	Includes removal of siding, possible sheathing/trim repair
Water Damage Remediation	$500–$5,000+	Costs escalate quickly if rot or mold is present

Investing early in proper flashing prevents major expenses down the road.

DIY Vs. Professional Kickout Flashing Installation

Skilled DIYers may attempt to install kickout flashing, especially on accessible, single-story roofs. However, for two-story heights, complex rooflines, or where removal of existing siding is required, hiring a licensed roofer is highly recommended. Improperly installed flashing can void warranties and may not pass home inspections.

When To Call A Professional

• Multiple, complex roof-to-wall transitions
• Unfamiliarity with building codes or roofing materials
• Signs of previous water damage or rot
• Unsafe working conditions

Professional installation often includes warranties on both materials and workmanship.

Kickout Flashing And Real Estate Inspections

Many homebuyers now request detailed roof and exterior envelope inspections. Missing or improperly installed kickout flashing is one of the most common issues flagged. Correction negotiates may be required for sales to proceed, giving sellers strong incentive to ensure kickout flashing is present and functional before listing.

Energy Efficiency And Home Health Implications

Properly installed kickout flashing not only protects against water infiltration, but also helps maintain:

• Consistent indoor humidity and temperature levels
• Reduced HVAC costs by protecting insulation from moisture
• Lower risk of mold, which can exacerbate allergies or respiratory problems
• Longer siding and trim lifespan—reducing cyclical repair costs

Best Practices And Advanced Tips For Roofers

Roofing professionals should adhere to these best practices for kickout flashing success:

1. Always use factory-bent, code-compliant kickout flashings instead of bending your own from scrap metal.
2. Prefit and test the flashing with actual siding and gutter profiles before fastening permanently.
3. Use compatible sealants and fasteners for all materials to avoid galvanic corrosion.
4. Educate clients and building inspectors about the necessity and function of kickout flashings.

Attention to detail is the key to leak-free installations.

Frequently Asked Questions About Kickout Flashing

• Is kickout flashing required by law? In most states and municipalities following the IRC, yes, kickout flashing at roof-to-wall intersections is required.
• Can I install kickout flashing without removing siding? Not usually. Proper installation generally requires peeling back at least one course of siding to tie flashing into the wall system.
• How often should kickout flashing be inspected or replaced? Annual inspections are recommended. Materials typically last 15–30 years depending on climate and exposure.
• Are plastic kickout flashings as good as metal ones? Quality polymer flashings are effective but may become brittle with UV exposure; metal lasts longer but must be corrosion-resistant.

Resources And Further Reading

• Building Science Corporation: Water Management in Building Envelopes
• International Association of Certified Home Inspectors (InterNACHI): Kickout Flashing: What Every Home Inspector Should Know
• International Code Council (ICC): Access to Building and Residential Codes
• Fine Homebuilding: Complete Kickout Flashing Installation Guide

Summary Table: Kickout Flashing Essentials

What	Why	Where	Materials	Inspection & Maintenance Tips
Metal/Plastic piece at roof/wall intersection	Prevents wall water damage by directing water into gutters	Where roof slopes end at side walls, porch/gable intersections	Galvanized steel, aluminum, copper, or UV-stable plastic	Inspect yearly, clear debris, repair/replace when damaged

Kickout flashing is a vital yet simple measure to protect homes and ensure long-term durability of roof and wall systems.