Why Getting Endwall Flashing Installation Right Can Save Your Roof
Endwall flashing installation is one of the most critical steps in any metal roofing project — and one of the most commonly done wrong. When protecting your home, partnering with a trusted provider of professional Texas Hill Country roofing services ensures your investment is completely shielded from the elements.
Here’s the quick answer on how to install endwall flashing correctly:
- Install sidewall trim first (if a sidewall condition exists)
- Cut and fit the flashing to match your roof pitch
- Apply butyl tape 1 inch from the edge along the panel ends
- Install profile-matched foam closures on top of the butyl tape
- Overlap flashing sections by a minimum of 6 inches
- Fasten with pancake screws (top section) and lap screws (lower section), 12 inches on center
- Seal all overlaps and foam closure tops with silicone or urethane sealant
An endwall is where your metal roof panels run up the slope and meet a perpendicular wall — like a house wall, chimney, or parapet. Without proper flashing at this joint, water doesn’t just drip — it gets driven sideways into your framing, insulation, and walls.
In Texas Hill Country, where storms roll in fast and temperatures swing hard, a bad roof-to-wall joint doesn’t stay a small problem for long. At Total Foundation & Roofing Repair, we see the consequences of skipped steps and undersized sealants every season.
I’m Daniel Sowell, owner of Total Foundation & Roofing Repair in Kerrville, Texas — with over 18 years of hands-on experience in endwall flashing installation and metal roofing across the Hill Country. In this guide, I’ll walk you through exactly how to get it done right the first time.
Endwall flashing installation terms to know:
- flashing a chimney on a metal roof
- installing metal roof transition flashing
- shingle to metal roof transition flashing
What is Endwall Flashing and Why is it Critical?
To understand how to protect your home, we must first look at how endwall flashing differs from sidewall flashing. Sidewall flashing runs parallel to the slope of your roof and the ribs of your metal panels. Endwall flashing, however, sits at the very top of your roof slope, running perpendicular to the panel ribs. Because of this orientation, gravity-fed water running down the vertical wall hits this transition head-on.
If this joint is not completely sealed, wind-driven rain will easily blow right under the metal panels. This is why proper design and high-quality materials are non-negotiable. While coastal building codes have strict requirements—as detailed in the Metal Roof Endwall Flashing Guide for Florida Roof-to-Wall Details —the exact same physics apply to homes in Comfort, Fredericksburg, and Kerrville. Intense Texas thunderstorms can drive rain horizontally, making a robust roof-to-wall transition absolutely necessary.
We always recommend using heavy-duty, corrosion-resistant metals like 26-gauge galvanized steel or .019-inch aluminum for your flashing. According to industry standards set by the Metal Construction Association, using the correct gauge and material compatibility is essential to prevent galvanic corrosion and ensure the longevity of the roof system. For a detailed breakdown on how these transitions integrate with other parts of your roof, check out our guide on installing metal roof transition flashing. For those looking for visual guides on general metal roof details, you can also check out this helpful resource on how to install endwall flashing for a metal roof step-by-step.
Step-by-Step Endwall Flashing Installation
Before grabbing your snips and drill, it helps to understand that different metal roofing panels require different flashing approaches.
| Feature | Exposed-Fastener Panels (e.g., 5V-Crimp, Corrugated) | Standing Seam Panels (e.g., SL-16, Snap-Lock) |
|---|---|---|
| Primary Seal Method | Profile-matched foam closures & butyl tape | Metal Z-trim (Z-bar) cut to fit between ribs |
| Fastener Location | Screws go through the high ribs of the panel | Fasteners are concealed under the locking trim |
| Thermal Movement | Rigidly fixed; less prone to panel shifting | High movement; requires floating panel setbacks |
Preparing the Roof for Endwall Flashing Installation
Preparation is the secret to a leak-free roof. If your roof has a corner where a sidewall meets an endwall, you must install all your sidewall trim prior to fastening any endwall flashing. To execute this installation flawlessly, you will need a reliable set of tools, including left and right-cut aviation snips, a hand seamer for clean bends, a caulking gun for high-grade polyurethane sealant, and a cordless drill with magnetic hex drivers.
Next, verify your panel setback. For standing seam systems, the metal panels must stop shortly before the wall to allow the metal to expand and contract during hot Texas summers. Before the metal panels are even laid down, a high-temperature self-adhering underlayment should be installed along the roof-to-wall transition. This ice and water shield acts as an extra layer of defense beneath the metal panels, ensuring that even if wind-driven rain manages to bypass the metal flashing, it cannot penetrate the roof deck.
Finally, check your wall’s water-resistive barrier (WRB), such as house wrap. The WRB must hang over the vertical leg of your metal endwall flashing in a shingle-like fashion. This ensures that any moisture running down behind your siding or stucco is directed out onto the metal flashing, rather than behind it. For more preparation tips, read our metal roof installation complete guide.
Step-by-Step Endwall Flashing Installation Procedures
Once your panels and sidewall trims are in place, follow these steps to install your endwall flashing:
- Dry-Fit and Mark: Place your first piece of endwall flashing against the wall and over the metal panels. Use a pencil to mark where the bottom edge of the flashing lands on the panel ribs.
- Apply Butyl Tape: Remove the flashing. Apply a continuous line of double-sided butyl tape exactly 1 inch uphill from your marks, directly onto the metal panels.
- Set the Closures: Press your profile-matched foam closures firmly onto the butyl tape. These closures must match the exact shape of your metal panels (such as corrugated or rib profiles) to block wind-driven rain and pests.
- Apply Sealant: Apply a generous bead of high-quality silicone or polyurethane sealant along the top of the foam closures. This creates a secondary line of defense against water.
If you are dealing with complex masonry intersections, such as chimneys, you will need to follow a specialized process. You can learn more about this in our guide on flashing a chimney on a metal roof.
Cutting, Overlapping, and Fastening the Flashing
When running multiple lengths of flashing, you must handle your overlaps correctly. Endwall flashing is typically sold in 10-foot lengths. To find out how many pieces you need, add up your total linear feet of endwall, divide by 9.5, and round up.
Every joint where two pieces of flashing meet must overlap by a minimum of 6 inches. To ensure a tight, flush fit at the overlap, notch the hemmed edge of the overlapping piece by cutting 6 inches back and 1/8 inch up from the hem.
Fastener Schedule:
- Vertical Wall Leg: Secure the vertical leg to the wall structure using pancake screws spaced 12 inches on center, placed 1 inch down from the top edge.
- Roof Leg: Secure the horizontal leg to the roof panels using lap screws with neoprene sealing washers. Space these 12 inches on center, driving them directly through the high ribs of the panel and through your foam closures.
Pro-Tip from Daniel: Always clean off metal shavings daily. When you cut metal trim, tiny steel shavings land on the roof. If left overnight, the morning dew in the Hill Country will cause them to rust, leaving permanent, ugly red stains on your beautiful new roof!
Sealing the System with Closures and Butyl Tape
Relying solely on caulk to seal a flat metal leg against a brick, stucco, or siding wall is a recipe for a future leak. Caulk eventually cracks and pulls away due to UV exposure and thermal expansion.
Instead, we highly recommend using a mechanical counterflashing or cutting a reglet joint into masonry and stucco walls. A reglet is a shallow groove cut into the wall where the top flange of the flashing tucks in. This joint is then sealed with a professional-grade polyurethane sealant, ensuring a completely watertight seal that cannot be bypassed by running water.
If your project involves transitioning from shingles to metal, you will need to pay extra attention to these seals. Be sure to read our guides on transitioning flashing from shingles to metal and our shingle to metal transition flashing guide for advanced techniques.
Professional Endwall Flashing Installation Services
While a handy homeowner can tackle basic flashing, getting a truly watertight seal on complex roof-to-wall transitions requires specialized tools and years of experience. A single missed detail can lead to hidden water damage inside your walls that costs thousands of dollars to repair.
At Total Foundation & Roofing, we provide certified, high-quality metal roofing and concrete services tailored specifically to the unique climate of the Texas Hill Country. Whether you are in Kerrville, Fredericksburg, or Comfort, our team delivers prompt, reliable service that stands up to the toughest Texas weather. We understand how the intense heat causes metal panels to expand and contract, and we design our flashing systems to accommodate this movement without failing.
Our comprehensive roofing services include detailed inspections, custom metal fabrication, and precision installations that adhere to the highest industry standards. Don’t risk the structural integrity of your home with DIY mistakes or subpar contractor work. Let our experienced professionals handle your next project safely and correctly. Get professional metal roofing services from our local team today to schedule your free inspection and secure your home for decades to come!
