You found two YouTube videos and three forum threads. One guy swears the screw goes on the rib. The next one says that’s how you get leaks. So which is right?
Here’s the short version: on most exposed-fastener metal roofs, the screw goes through the flat of the panel, right next to the rib, not through the rib itself. That’s the placement that major panel makers like McElroy Metal, Metal Sales, and Union Corrugating spec for installers. But the full answer has a catch, and that catch is exactly why the internet can’t agree.
If you’re weighing a new metal roof or trying to figure out why your current one keeps weeping at the screws, this breaks down the real reason, the data behind it, and when the “flat” rule flips. If you’d rather hand the whole question to someone local, our metal roofing services in Hanover cover panel selection and proper fastening from the start.
Quick Answer: Flat of the Panel, Next to the Rib
For trapezoidal exposed-fastener panels (R-panel and PBR), drive screws through the flat next to the rib. This lets the rubber washer compress evenly against a solid, flat surface, and it lets the screw thread bite down into the roof deck.
When you screw through the raised rib instead, the panel lifts the screw away from the deck. Part of the shank sits in open air, the washer can’t seat flat, and a chunk of the thread never grips anything. According to Mason Burchette, owner and COO of True Metal Supply, rib placement leaves a large portion of the fastener’s thread exposed and not biting into the deck (via Metal Construction News).
Metal Roofing Magazine, citing McElroy Metal, notes that flat-of-panel placement gives the best protection against leaks while also helping the building’s overall structural strength.
So Why Does Everyone Online Disagree?
Because both camps are partly right, and that’s the part most blogs skip.
Placement depends on your panel profile:
- R-panel and PBR profiles: fasten through the flat. This is the modern standard.
- Round or sinusoidal corrugated panels, and some high-snow-load setups: were historically engineered for crest (rib) fastening. According to Indiana Metal, some manufacturers do specify rib fastening for certain profiles, especially in heavy-snow regions where point loading on the panel matters.
- Standing seam: no exposed screws on the panel face at all (more on that below).
So when one person online says “rib” and another says “flat,” they may both be quoting a real instruction for a different panel. The authority is never a forum. It’s the installation guide for your specific panel. As McElroy Metal puts it on its own blog, there is no single hard-and-fast rule across all panel types, because each system is designed and tested to be attached a specific way.
That’s the honest answer this keyword exists to settle.
How a Correctly Placed Screw Still Fails Over Time
Even a perfect flat-of-panel screw doesn’t last forever, and knowing why helps you plan.
Metal panels expand and contract with heat. Steel grows about 0.0000065 inches per inch for every degree Fahrenheit. Over a 150-degree swing, a 20-foot steel panel moves roughly 1/4 inch, and a 40-foot panel moves about 1/2 inch. Aluminum moves about twice as much (Projul). ASC Profiles senior engineer Brian Gough offers a simple field rule of about 1/8 inch of movement per 10 feet of panel (via Metal Construction News).
Here’s what that constant movement does. The panel slides a hair against the fixed screw, over and over, for years. Building Research Systems describes the result as the hole slowly tearing and piling up around the screw shank. Once that slot grows wider than the sealing washer covers, you have a leak. This is called thermal-induced hole elongation, and it’s the cause most articles never name.
The rubber washer is the other weak point. Field consensus from roofers and suppliers puts washer hardening and leaks around the 20 to 30 year mark. If you’ve already spotted rust streaks or staining below screw heads, that’s your cue to schedule a roof leak inspection before water reaches the deck.
Flat vs. Rib at a Glance
| Factor | Through the Flat (next to rib) | Through the Rib |
| Washer seal | Compresses evenly on a flat surface | Can’t seat flat, uneven seal |
| Thread grip on deck | Full bite into the deck | Much of the thread never reaches the deck |
| Leak risk | Lower | Higher |
| Manufacturer spec | Standard for R-panel and PBR | Specified only for certain profiles or snow loads |
Sources: McElroy Metal, True Metal Supply via Metal Construction News, Indiana Metal.
How Many Screws Are We Talking About?
This is where the leak math gets real.
A typical residential metal roof uses 80 to 120 screws per square (100 square feet), per Reston Roofing. So a 2,000-square-foot home means roughly 1,600 to 2,400 individual holes in your roof. Older spec sheets vary: Fabral cited 80 screws per square, Midwest Manufacturing specified 75 (InspectAPedia, citing manufacturer data).
Martini Roofing frames the stakes plainly: a roof can hold 2,000 or more exposed fasteners, and every one is a possible entry point for moisture as the years pass.
That’s a lot of potential failure points, which is why placement, spacing, and torque all matter so much.
Spacing and Torque: The Details That Separate a 10-Year Roof From a 30-Year One
Spacing. Field zones generally run about 12-inch fastener spacing, with tighter spacing at perimeters and tighter still at corners. High-wind areas require doubling fastener frequency at the perimeter by code (SolaRoof; New England Metal Roof). General field schedules land in the 12 to 24 inch range depending on the manufacturer.
Torque. Snug, not crushed. Tighten until the rubber washer compresses evenly. If the washer bulges out the sides, it’s overdriven, and that ruins the seal (Fong Prean). Under-driven is just as bad.
Tools. Skip the impact driver. The high torque can snap the head clean off the screw body, and Burchette specifically warns against impact tools for this reason. A torque-controlled or depth-sensing driver is the right call.
These three variables are judgment calls, not numbers you can copy from a video. That’s a big reason fastening is one of the easier parts of a metal roof to get wrong.
The Building Code Angle (Why This Isn’t Just a Free-for-All Opinion)
Placement isn’t only craftsmanship. It’s tied to code.
IBC Section 1507.4.4 states that metal roof panels must be secured according to the approved manufacturer’s fastener instructions. Where no manufacturer recommendation exists, the code defaults to galvanized fasteners for steel roofs (IBC 1507.4).
Wind resistance is also code-mandated: roof coverings must be designed to resist component and cladding wind pressures under Section 1609. There’s a materials note too. Under 2024 IBC Table 1507.4.3, lighter G60 coating applies only to certain accessory-type structures, meaning occupied buildings need heavier corrosion protection (ICC-ES ESR-2385, Metal Sales).
Why this matters for you: deviating from the tested attachment method can fail inspection and void your panel warranty. That’s a solid reason to match your specific panel’s guide rather than guess, and to bring in a licensed installer if there’s any doubt.
The Plot Twist: Standing Seam Has No Exposed Screws at All
Here’s the answer that changes the whole question.
If “where do the screws go” is keeping you up at night, the cleanest fix is a system where they don’t go through the panel at all. Standing seam roofs have zero exposed screws on the panel face. They use concealed clips instead (SolaRoof).
Those clips do something exposed fasteners can’t. The panel floats above the structure and slides within the clip as it heats and cools, per AEP Span technical rep Jeff Haddock. Building Research Systems describes the whole roof acting like a steel membrane that moves freely with expansion and contraction.
The payoff shows up in lifespan. Berridge staff engineer Bobby Marks Jr. points out that concealed-clip systems aren’t subject to fastener corrosion, seal breakdown, or thermal hole elongation, and that a standing seam panel often functions as a permanent roof while a through-fastened system has a limited life cycle (via Metal Construction News).
| Factor | Exposed Fastener | Standing Seam |
| Exposed screws on the face | 80 to 120 per square | 0 |
| Typical lifespan | 20 to 30 years | 40 to 60 years or more |
| Thermal movement | Screw holes can slot and elongate | Clips let the panel float |
| Relative cost | Lower | Roughly 30 to 50% more |
Sources: Alta Roofing, 614 Exteriors, Martini Roofing, SolaRoof.
The trade-off is the upfront cost. Standing seam runs roughly 30 to 50% more than an exposed-fastener system for the same roof, in exchange for the longer life and almost no fastener upkeep (Martini Roofing).
Not Sure Which Profile You Have? Let’s Look at It Together
Panel profiles, fastener sequences, and snow or wind requirements all shift the right answer, and getting it wrong is expensive to undo. The team at Bealing Roofing & Exteriors can identify your panel, confirm the correct placement for it, and walk you through whether an exposed-fastener repair or a standing seam upgrade fits your home and budget. Reach out for a straightforward look at your roof, no pressure attached.
Frequently Asked Questions
Do screws go on the rib or the flat of a metal roof? On R-panel and PBR exposed-fastener panels, the flat next to the rib. That placement lets the washer seal flat and the thread grip the deck. Certain corrugated and high-snow profiles call for rib fastening, so check your panel’s guide.
Why shouldn’t you screw into the rib of a metal roof? The rib holds the screw up off the deck, so the washer can’t seat flat and much of the thread never bites into anything solid. The result is a weaker hold and a higher chance of leaks.
How tight should metal roofing screws be? Tighten until the rubber washer compresses evenly with the panel. If it bulges or squeezes out the sides, it’s too tight. A loose screw leaks, an overdriven one leaks too.
Should you use an impact driver for metal roofing screws? No. The high torque can separate the screw head from the body. Use a torque-controlled or depth-sensing driver so you stop at the right depth every time.
How many screws does a metal roof need? Roughly 80 to 120 per square (100 square feet), so a 2,000-square-foot roof needs about 1,600 to 2,400 fasteners, per Reston Roofing. Your exact count depends on the panel and spacing schedule.
How often should metal roof screws be checked? Most guidance suggests inspecting screws every 5 to 10 years, and sooner after a severe storm. The rubber washers tend to harden and leak around the 20 to 30 year mark.
Do standing seam metal roofs have exposed screws? No. They fasten with concealed clips, so there are zero exposed screws on the panel face. That’s the main reason they outlast exposed-fastener systems.
Does screw placement affect my warranty? It can. IBC 1507.4.4 ties attachment to the manufacturer’s tested method, and installing outside that spec can fail inspection or void the panel warranty.
Bealing Roofing & Exteriors, Inc. is based in Hanover, Pennsylvania, serving south-central Pennsylvania and northern Maryland with metal and asphalt roofing, siding, insulation, and repair services.