The kick-out flashing on roof transitions directs water away from the wall where the roof meets a vertical surface, reducing risks of leaks, rot, and costly repairs. This article explains what kick-out flashing is, why it matters, code considerations, materials, installation options, common mistakes, maintenance, and cost expectations for U.S. homeowners and contractors.
| Aspect | Summary |
|---|---|
| What It Is | Short Metal Flashing That Diverts Rainwater |
| Main Purpose | Keep Water Off Vertical Siding And Prevent Wall Penetration |
| Common Materials | Galvanized Steel, Aluminum, Copper |
| Typical Cost | $20–$150 For Materials; $150–$600 Installed |
What Is Kick-Out Flashing And Why It Matters
Kick-out flashing, sometimes called diverter flashing, is a small angled piece of metal installed at the intersection where a sloped roof terminates against a vertical wall. Its primary function is to channel roof runoff away from the wall face and into the gutter system rather than allowing water to cascade down the siding or behind the cladding.
Without properly installed kick-out flashing, water can infiltrate the wall assembly, leading to stained siding, rot, mold, insect intrusion, and structural damage. Addressing this detail is a low-cost preventive measure with high long-term payoff.
Where Kick-Out Flashing Is Required By Code
Many model codes and local jurisdictions require flashing at roof-to-wall intersections. The International Residential Code (IRC) and local amendments emphasize flashings to prevent water intrusion. Inspectors typically look for continuous metal flashing that turns water away from the wall and ties into the roof underlayment and gutter.
Since enforcement varies, contractors and homeowners should check local building codes, homeowners association rules, and the municipality’s permitting office for specifics. When in doubt, follow manufacturer recommendations and accepted construction practices.
Materials And Types Of Kick-Out Flashing
Kick-out flashing comes in several materials and profiles. Common materials include galvanized steel, aluminum, and copper. Galvanized steel is economical and durable; aluminum is lightweight and corrosion-resistant; copper offers long life and aesthetics.
Profile types include L-shaped, Z-shaped, and factory-formed kick-outs that integrate with step flashing. Some systems pair a short diverter with step flashing or a continuous wall flashing called a headwall flashing. Choice depends on roof pitch, siding type, and aesthetic preferences.
Correct Installation Principles
Proper installation is essential. The kick-out flashing must: slip under the roof underlayment or shingles, extend over the gutter or be positioned to direct water into it, and turn outward at least 2 inches from the wall face. Integration with roofing underlayment, step flashing, and housewrap is critical to create a continuous drainage plane.
Key installation steps include: remove shingles where flashing will sit, slide the flashing under the underlayment or shingles, fasten to the roof deck—not the siding—seal where appropriate with compatible sealant, and lap with step flashing pieces to avoid gaps. Proper laps are typically a minimum of 2 inches unless manufacturer specifies otherwise.
Step-By-Step Installation Overview
- Prepare The Area: Remove roofing and underlayment where the kick-out will be installed and expose the roof deck and sheathing.
- Install Housewrap And Underlayment: Ensure housewrap is lapped over the wall flashing and a high-quality underlayment covers the roof approach.
- Position Kick-Out Flashing: Slide the flashing under the underlayment; the diverter should extend down and out toward the gutter.
- Integrate Step Flashing: Overlap step flashing pieces over the kick-out so each shingle course is protected.
- Secure And Seal: Fasten to the roof deck and apply compatible sealant sparingly at transitions, avoiding overreliance on sealant as the primary waterproofing method.
Common Mistakes And How To Avoid Them
Frequent errors include installing kick-out flashing too short to clear the siding, failing to integrate with step flashing, fastening into siding surfaces, and relying on caulk instead of correct overlaps. Each of these mistakes can create a pathway for moisture despite having a flashing piece in place.
Another mistake is placing the kick-out too high or too low relative to the gutter. Ideally, it should deliver water directly into the gutter or over the gutter flange to prevent water running down the exterior wall.
DIY Versus Hiring A Professional
Smaller repairs or retrofit installations may be feasible for a competent DIYer with roofing experience and proper safety equipment. However, improper installation can cause worse damage, so homeowners should consider a licensed roofer, especially where siding, complex rooflines, or multi-story access is involved.
Professional installers bring knowledge of code requirements, access to proper flashing materials, and techniques for integrating with existing roofing systems and gutters. Licensing, insurance, and local references are important when selecting a contractor.
Maintenance And Inspection Tips
Periodic inspection helps catch failing flashings early. After storms or at least annually, check the junctions where roofs meet walls, look for rusted or loose flashings, and inspect for water stains or softened siding. Prompt repairs are less costly than addressing hidden rot or mold.
Keep gutters clean to ensure the kick-out functions as intended. If gutters are clogged, water may overflow and bypass the flashing, causing wall exposure. Proper gutter slope and capacity help the system perform reliably.
Cost Expectations And Budgeting
Material costs for kick-out flashing range from about $20 for simple aluminum pieces to over $100 for copper or custom-formed units. Labor costs for installation vary widely—typical professional installs are $150–$600 depending on roof access, complexity, and local labor rates.
For roof replacement projects, including kick-out flashing during roofing installation is cost-effective because it avoids additional tear-off or disruption later. Budgeting for quality materials and professional labor reduces long-term maintenance and repair costs.
Alternatives And Complementary Details
While kick-out flashing is the recommended detail, complementary solutions include continuous headwall flashing, through-wall flashing behind cladding, and use of waterproofed sheathing in high-exposure areas. These measures are often used together to create redundancies that protect the wall assembly.
In some retrofit scenarios, a short gutter extension or diverter might be used temporarily, but these are not substitutes for a properly integrated kick-out flashing tied into the roofing and wall drainage systems. Permanent metal flashing integrated with the roof assembly is best practice.
How To Inspect A Kick-Out Flashing Job
- Verify Proper Lapping: Flashing should slip under shingles or underlayment and overlap step flashing pieces.
- Check Diverter Length: The kick-out should extend at least 2 inches past the wall cladding to clear the siding.
- Look For Fastener Placement: Fasteners should be in the roof deck, not the siding or housewrap.
- Confirm Gutter Alignment: Water diverted by the kick-out should flow into the gutter or over the gutter flange.
- Assess Sealant Use: Sealant should be minimal and compatible—flashing relies on mechanical laps more than caulking.
Resources And Further Reading
Trusted resources include the International Residential Code (IRC) flashing requirements, manufacturer installation guides for metal flashing, and instructional materials from roof trade organizations. Local building departments can provide code interpretations and permit requirements.
For visual learners, reputable contractor associations and roofing manufacturers often provide diagrams and videos showing proper kick-out flashing details. Searching for terms like “kick-out flashing installation diagram” or “roof-to-wall flashing detail” yields helpful references.