How to Find the Right Fastening Layout for Your Metal Roof

Tony Marsh Aug 26, 2026 · 22 min read

The short answer: start with the panel-specific fastening drawing

The correct metal roof screw pattern is the one approved for the exact panel, material, substrate, support arrangement, roof zone, and project loads. Do not select a pattern from roof area, appearance, a generic screws-per-square estimate, or an online rule such as “fasten every 12 inches.”

Identify and reconcile all controlling documents:

Applicable building-code and permit requirements
Approved permit drawings
Project-specific engineered plans
Product approvals or tested roof assemblies
The panel manufacturer’s current installation instructions, fastening diagrams, and load tables
Project specifications, warranty conditions, and inspection requirements

If they conflict, stop work and have the conflict resolved by the design professional, panel manufacturer, permit authority, or other party responsible for approving the installation. Do not quietly choose the option that is easiest or uses fewer screws.

A fastening layout controls more than leakage around sealing washers. It affects how panel loads transfer into decking, framing, or purlins and how the assembly responds to wind uplift, snow loads, panel flexing, and pull-off forces. Panel system, substrate, support spacing, roof shape, roof zone, eave height, and environmental loads can all affect the required arrangement, according to McElroy Metal’s overview of roofing fastener patterns.

The pattern may change across the same roof. Interior field areas, panel ends, eaves, ridges, perimeters, and corners can have different approved schedules because loading and attachment requirements may vary by location. Lap screws, closures, and sealant can also have requirements separate from the main structural-fastener schedule.

A drawing labeled for corrugated roofing, R-panel, 7.2-rib, ABM, or another named product is not a generic template. Two panels can look almost identical from the ground yet differ in coverage width, rib geometry, material, gauge, support spacing, lap construction, or approved fastener position.

Important: Every screw count and dimension later in this article is an attributed example from a particular supplier’s guidance. The examples show how to interpret a fastening diagram; they are not specifications for your roof.

Use roof area to estimate fastener quantities only after establishing the approved screw pattern, screw-line spacing, lap schedule, roof-zone changes, and waste allowance. Area alone cannot determine attachment design.

A practical decision sequence is:

Identify the exact roof system and panel.
Identify the substrate and support layout.
Obtain the applicable approved drawing or fastening table.
Match the drawing to the project’s material, loads, and roof zones.
Separate structural fasteners from lap and trim fasteners.
Mark supports and screw locations from the approved detail.
Stop and request technical review if any condition is undocumented.

Identify the roof system before interpreting any screw diagram

First determine whether the roof is an exposed-fastener panel system or a concealed-fastener standing-seam system.

Exposed-fastener panels have visible screws penetrating the panel face. Their drawings commonly show cross-panel screw lines, fastener positions relative to ribs or pans, panel-end patterns, and sidelap details.

Standing-seam systems commonly attach through concealed clips or screw flanges. They do not use a generic exposed-screw field pattern. Clips, flanges, closures, and cleats are parts of the assembly and must be installed where the applicable documents require them. Some clip systems secure the panel while permitting expansion and contraction; other systems use a concealed screw flange. The distinction is illustrated in this Florida supplier’s overview of exposed- and hidden-fastener systems.

Before interpreting a diagram, record the following information.

Panel and material details

Manufacturer
Exact product name and model
Panel profile
Coverage width and overall width, if both are listed
Rib or corrugation dimensions
Material type
Material thickness or gauge
Factory finish where it affects fastener compatibility
Roof or wall application
Sidelap direction and overlap configuration
Presence of a purlin-bearing leg, anti-siphon feature, or other profile detail

Do not assume that a siding pattern is approved for roofing merely because the same panel is marketed for both uses. Roof and wall schedules may differ.

Structure and geometry

Decking or substrate material
Substrate thickness and condition where relevant to the assembly
Framing or purlin type
Support orientation
Support spacing
Roof pitch
Eave height
Panel length
Roof shape
Overhangs
Valleys, hips, dormers, transitions, and penetrations
Open, partially enclosed, or enclosed building conditions where addressed by the project documents
Project location and applicable environmental criteria

A visible screw line is useful only if it corresponds with the intended support or an approved deck-fastened arrangement. On a purlin roof, evenly spaced marks up the panel do not establish a valid layout if the screws miss the purlins.

Design and approval documents

Confirm the applicable:

Wind and snow criteria
Roof-zone plan
Field, perimeter, corner, eave, ridge, and panel-end schedules
Product approval or tested assembly
Permit drawings
Project specifications
Engineered plans
Manufacturer load tables
Approved support spacing
Fastener type and location
Sidelap fasteners and sealant
End-lap and trim details
Warranty conditions
Local inspection requirements

A Florida product-approval drawing is one example of wind-load-specific documentation. In one Florida supplier’s explanation, an approval may identify “pattern A” as a standard arrangement and “pattern B” as a tighter arrangement for higher wind loads. Those labels belong to that approval context and are not national fastening terminology. The applicable panel, material, substrate, design loads, approval, and permit documents still determine which arrangement may be used.

If the existing panel is unknown

Do not identify an existing panel solely by saying it “looks like R-panel” or “looks like corrugated roofing.” Gather:

Original invoices, delivery tickets, and warranty documents
Packaging labels or leftover panel markings
Panel coverage and overall width
Rib spacing, rib height, and pan dimensions
Sidelap shape and direction
End-lap details
Clear photographs of the panel face and underside
Photographs of eaves, ridges, laps, and fastener rows
Fastener-head markings, if legible
Information about decking, framing, or purlins below the panels

Send the information to the original supplier or manufacturer if known. Otherwise, ask a qualified roofing professional to inspect the system. A visual match with a web photograph does not establish that two products share an approval or fastening schedule.

Stop work and obtain technical review when:

The panel manufacturer or model cannot be established.
The fastening drawing is missing, incomplete, or obsolete.
The substrate type, thickness, or condition is uncertain.
Manufacturer instructions conflict with permit or engineered documents.
The building is tall, highly exposed, open-sided, or unusually shaped.
The project has high-wind requirements.
Support spacing falls outside the published assembly.
The roof contains unusual transitions or unsupported panel conditions.
A proposed repair would alter an engineered layout.
No approved detail addresses the actual condition.

Depending on the problem, review may need to come from the panel manufacturer, design professional, permit authority, or structural engineer. Resolving uncertainty before drilling panels is more reliable than trying to justify an improvised pattern afterward.

Learn the parts of a fastening pattern

A fastening drawing becomes easier to interpret when rows, fasteners, laps, and roof areas are treated as separate functions.

Screw line or fastener row

A screw line, also called a fastener row, is a repeated line of fasteners across the panel width. It normally corresponds with an approved support location or another position established by the roof assembly.

A drawing may distinguish among:

Rows at panel ends
Interior rows
Rows at eaves or ridges
Rows in perimeter or corner zones
Rows at end laps

“Screw line” does not imply a universal distance between rows. Row spacing may follow purlin spacing, framing layout, an approved deck-fastened schedule, a load table, or project-specific engineering.

Structural or framing fasteners

Structural panel fasteners provide the primary attachment between the panel and the approved substructure. Depending on the assembly, that substructure may be:

Wood framing
Wood decking
Steel framing
Steel purlins
Another specifically approved substrate

The fastener must engage the support or decking assumed by the assembly. A screw that penetrates the sheet but misses a purlin does not create the connection represented by a purlin-fastened pattern. A screw driven into deteriorated material may also appear properly positioned from above while lacking the expected holding capacity.

Stitch or lap fasteners

A stitch screw or lap screw joins one metal component to another. Common applications include panel sidelaps and some trim connections. It does not necessarily penetrate the roof substructure.

That distinction matters when reading a count. “Five panel screws plus one lap screw” does not mean six interchangeable structural fasteners. The lap screw serves a different function and may have a different specification.

Panel ends, field areas, and higher-uplift zones

The field is the broad interior portion of the roof. Panel ends, perimeters, corners, eaves, and ridges may have different approved attachment requirements.

Do not assume that the tightest-looking row should be repeated everywhere. Extra penetrations are not automatically beneficial. Conversely, do not extend a lighter interior pattern into an edge or panel-end condition unless the controlling documents show that arrangement.

Read the roof-zone map and fastening schedule together. A screw pattern without its zone boundaries is incomplete.

Sidelaps, overlaps, and sealant

Sidelaps require separate attention because they involve at least three questions:

How far and in what direction do the panels overlap?
Where and how often are lap fasteners installed?
Is butyl tape, mastic, or another sealant required?

The main structural pattern may not answer those questions. Some lower-slope exposed-fastener applications call for sidelap sealant to limit capillary leakage, but the slope threshold and sealant position must come from the applicable panel documents.

Purlin-bearing leg

Some profiles include a purlin-bearing leg, an extended panel-edge leg that rests on a purlin. On profiles designed with this feature, it can support the overlap and help keep the leading rib aligned during fastening. Sidelap sealant and purlin-bearing-leg functions are discussed in McElroy Metal’s manufacturer guidance, but neither feature establishes a universal screw pattern.

Rib, near-rib flat, or center pan: why the answer depends on the profile

The ribs are the raised portions running along a panel. The flats, also called valleys or pans, are the lower portions between ribs.

Metal-roof screws do not always belong through the rib, and they do not always belong in the flat. Both blanket rules are wrong.

For ABM exposed-fastener panels, Cumberland Supply directs installers to place metal-to-wood screws in the bottom flat beside the major rib, follow the official pattern, and engage solid framing or decking. The supplier’s stated rationale is that the washer can sit on a flat surface while the screw makes a direct connection to the support, as described in its ABM panel fastening guidance.

Indiana Metal gives another manufacturer-specific version of near-rib fastening. For the exposed-fastener applications it discusses, the company calls for screws in the flat approximately 1 to 2 inches from the rib, rather than through the rib or in the center of the pan. It also acknowledges that some manufacturers specify rib fastening for particular profiles, reinforcing that the location is system-specific in its rib-versus-flat guidance.

Commonly reported considerations include:

Near-rib flat: The panel is close to the support, and the washer can bear against an even surface. The nearby rib may make this part of the pan less flexible than its center.
Center pan: The washer still bears on a flat surface, but some manufacturers avoid the center because it may be a primary drainage path or a more flexible part of the panel.
Rib or corrugation high: The penetration is higher in the profile, but there may be a gap between the panel and the substrate. The profile and fastener must be intended for that condition.

These considerations are explanations offered in supplier and manufacturer guidance, not independent comparative test results. They cannot substitute for the tested or approved panel detail.

Some corrugated-panel instructions accept or require fastening through the high; others use the low. Western States Metal Roofing illustrates both approaches and expressly notes that manufacturers differ in its panel-specific fastening examples.

Do not decide by choosing whichever general argument sounds most convincing. Mark each screw location from the exact panel drawing.

Illustrative patterns for corrugated, R-panel, and 7.2-rib roofing

The examples below show how profile, width, row type, and lap treatment can change a fastening diagram. Every number in the table comes from one supplier’s corrugated, R-panel, and 7.2-panel examples and must remain tied to that source.

Panel example	Panel width where supplied	Panel-end row	Interior row	Sidelap treatment	Limitation
7/8-inch corrugated roofing example	37 inches	Four screws per screw line, approximately every third corrugation	Four screws per screw line, approximately every third corrugation	The source’s layout identifies a fastener at the overlap	Example only; high-versus-low placement depends on the applicable manufacturer’s instructions
7/8-inch corrugated roofing example	39 inches	Four screws per line, with one interval extending to the fourth corrugation	Four screws per line using the width-specific sequence	Overlap must follow the source’s panel arrangement	A two-inch width difference changes the sequence even though the screw count remains four
R-panel roofing or siding example	Not supplied in the available evidence	Five panel screws plus one lap screw	Three panel screws plus one lap screw	Lap screws at 12–18 inches on center, with butyl or mastic tape	Source-specific guidance, not a transferable R-panel rule
7.2 Panel/Western Rib example	Not supplied in the available evidence	End-versus-interior distinction unavailable in the cited excerpt	End-versus-interior distinction unavailable in the cited excerpt	Five panel screws plus one lap screw are described per screw line; a panel screw is placed in every panel low	The available evidence does not support an exact lap-screw interval

The two corrugated examples show why screw count and visual sequence are not the same thing. The cited 37-inch and 39-inch panels both use four screws per line, but the wider panel requires one interval to reach the fourth corrugation.

The R-panel example demonstrates why row type matters. Panel-end lines use five structural panel screws plus one lap screw, while interior lines use three panel screws plus one lap screw. A crew working from only the interior illustration could mistakenly carry the lighter arrangement to the panel end.

The R-panel source separately describes lap screws at 12 to 18 inches on center and calls for butyl or mastic tape. Those details belong only to the source’s application. They do not establish a universal lap interval, structural-row spacing, or sealant rule.

For the cited 7.2 Panel or Western Rib example, the available evidence supports only these statements:

Five panel screws plus one lap screw are described per screw line.
A panel screw is placed in every panel low.
The available excerpt does not establish a different end and interior schedule.
The available excerpt does not provide a complete lap-screw interval.

No additional spacing should be inferred.

Any of these examples can become inapplicable when the panel profile, width, material, gauge, substrate, support spacing, roof zone, or design load changes. Use the table to understand drawing notation—not to approve an installation.

Why spacing changes across roofs and projects

There is no supported universal answer to “How far apart should metal-roof screws be?” until the complete assembly and project conditions are known.

Panel geometry and material

Profile depth, rib spacing, panel width, material, and gauge affect how a panel spans and transfers load. A broad pan does not behave exactly like a narrow corrugation. Manufacturer guidance also indicates that lighter-gauge panels may require more attachment to limit bending or buckling, but any change must remain within a tested or engineered system.

Do not compensate for an unidentified or unverified panel by arbitrarily tightening the spacing. More screws cannot convert an unknown assembly into an approved one.

Material can matter independently of profile. An approval may provide different attachment schedules for steel and aluminum even when the panels appear similar.

Substrate and support spacing

Wood framing, steel purlins, decking, and concrete involve different fasteners and connection behavior. Thread engagement and pullout considerations are not interchangeable among substrates.

Two roofs can therefore display the same number of screw heads while having different attachment capacity. On one roof, every screw may engage sound framing. On another, screws may barely engage decking, miss purlins, or enter deteriorated wood.

Support spacing also determines where screw rows can perform their intended function. If an assembly was approved for one support arrangement, retaining the same number of screws while increasing the panel span does not preserve that assembly.

Roof slope, shape, height, and location

Roof slope, shape, eave height, building exposure, and project location can affect environmental loading and the resulting attachment schedule. Hips, valleys, corners, overhangs, and transitions may create conditions that are not represented by a simple rectangular-roof diagram.

That is why fastening schedules often appear alongside load tables, support-spacing limits, and zone drawings rather than as one isolated picture.

Roof zones

A complete layout may distinguish among:

Interior field
Perimeter
Corners
Eaves
Ridges
Rakes
Panel ends
End laps
Areas around openings or transitions

These terms do not establish fixed national zone widths. The applicable approval, permit drawings, or engineering must define the boundaries and the pattern used within each zone.

Florida terminology provides a useful illustration but not a national rule. In the supplier explanation discussed earlier, pattern A is a standard arrangement and pattern B is a tighter arrangement for higher wind loads. The correct arrangement still depends on the approved panel, material, substrate, permit documents, and project wind criteria within that Florida-focused approval context.

Too few screws versus too many

Too few structural fasteners—or rows spaced farther apart than the engineered layout—can permit panels to flutter and flex under wind, which may contribute to loosening and inadequate uplift attachment. Simply adding screws is not automatically safer: extra fasteners create extra penetrations and can restrict intended panel movement or contribute to tearing around holes. Fastener manufacturer SFS warns against both under-fastening and excessive fastening when discussing preservation of engineered fastener locations during metal-roof screw replacement.

The objective is not the largest possible screw count. It is the specified fastener type and approved pattern, installed into sound supports in each roof zone.

What about the commonly repeated 12-to-18-inch range?

A 12-to-18-inch range appears in some general guidance and in the cited R-panel example for lap screws. It is not a universal structural-row spacing, sidelap interval, or high-wind specification.

Before using any published dimension, determine exactly what it measures:

Structural screws across the panel?
Distance between screw lines up the slope?
Stitch screws along a sidelap?
Trim fasteners?
A particular roof zone?
A specific panel, material, and substrate?

If the source does not answer those questions, the number cannot override the panel drawing.

Install every fastener so the approved pattern can perform

Even a correct layout may not perform as intended if the wrong fasteners are used, support engagement is inadequate, or sealing washers are installed poorly.

Use the fastener specified for the panel and substrate, including its:

Material
Thread form
Diameter
Length
Point or drilling feature
Head style
Coating or corrosion protection
Sealing washer
Compatibility with the panel material and environment

There is no universal screw size, thread, coating, or embedment depth for every metal roof. Wood, metal-to-metal, and concrete fasteners are not interchangeable merely because their heads look similar.

Structural screws must engage the framing, purlin, or approved decking represented by the assembly. Penetrating only the sheet metal does not create the intended structural attachment.

Installation sequence

Confirm the drawing. Identify panel orientation, roof zone, row type, screw position, overlap, and lap-fastener schedule.
Mark the supports. Locate framing or purlins accurately instead of estimating their positions through the panel.
Establish the screw lines. Use controlled marks that remain square and correspond with the approved supports or dimensions.
Align the panel. Keep it square to the eave or other specified control line.
Form the lap correctly. Verify coverage width, lap direction, bearing leg, tape, sealant, and closures before fastening over them.
Place each screw at the diagrammed point. Do not drift from a near-rib position to the center pan or from a low to a high because the alternate location is easier to reach.
Hold the tool perpendicular. Keep the screw square to the panel surface.
Drive at a controlled speed. Stop when the washer forms the required seal without panel distortion.
Check engagement. Confirm that structural screws reached the intended support.
Review the completed row. Correct an early alignment error before it repeats across the roof.

Indiana Metal recommends an adjustable-clutch drill instead of an impact driver for the exposed-fastener applications in its guidance. That is product-specific advice, not a universal prohibition on impact drivers.

Washer-seating troubleshooting guide

Underdriven	Correctly driven	Overdriven	Angled
Washer is loose or incompletely compressed; the screw head may stand visibly above it	Washer is compressed firmly and evenly without excessive bulging	Washer bulges, splits, extrudes, or is crushed; the panel may be dimpled	Washer compression is uneven, often leaving one side inadequately sealed
May leave an incomplete seal and may not hold the sheet firmly	Creates the intended seal while avoiding unnecessary panel deformation	Can damage the washer, deform the panel, or compromise the hole	May prevent a complete seal and can enlarge or distort the hole
Confirm alignment, support engagement, and hole condition before correcting	No correction is needed if position and support engagement are also correct	Evaluate the washer, panel, hole, and support before using an approved replacement	Remove and repair using a method approved for the panel and substrate

Do not respond to an underdriven fastener by automatically applying more torque. First confirm that the screw is straight, properly engaged, and not spinning in a stripped hole.

Cumberland Supply’s ABM guidance calls for straight driving and washer compression that seals without making the washer bulge or the panel dimple when installing those exposed-fastener panels.

Crooked, stripped, or washer-damaged fasteners should be replaced using a repair compatible with the panel, hole, and substrate. Repeatedly driving the same screw into a compromised hole does not restore lost thread engagement.

Final quality-control pass

Before treating an area as complete, inspect for:

Straight, consistent screw lines
Correct panel-end and interior patterns
Correct zone transitions
Screws that missed framing or purlins
Underdriven or spinning screws
Angled screws
Crushed, split, or displaced washers
Panel dimpling
Incorrect rib, flat, or pan placement
Damaged coatings
Missing lap fasteners
Unsealed or incorrectly formed laps
Sealant displaced during installation
Missing closures
Deviations from the approved drawing

A neat-looking row is not enough. Verify both the visible installation above the panel and structural engagement below it.

Inspect and repair an existing screw pattern without improvising

Before removing fasteners, document the existing roof. This is especially important when the original attachment was engineered or when removing rows would erase evidence of support locations.

Record:

Screw-row positions and spacing
Differences between panel-end and interior rows
Perimeter and corner patterns
Sidelap fasteners
Panel coverage and lap direction
Known purlin or framing locations
Loose, missing, or previously replaced screws
Corrosion and washer condition
Panel dimpling
Leakage locations
Movement or flutter reported during wind
Areas affected by impact or severe weather

Use photographs, measurements, and a roof sketch. Mark each symptom before disturbing the assembly.

Symptom-to-check framework

Symptom	What to check
Leak near a screw	Screw angle, washer compression, washer damage, corrosion, panel dimpling, enlarged hole, and whether water is entering at a nearby lap or flashing
Leak along a sidelap	Lap direction, overlap, lap-fastener spacing, missing or displaced sealant, possible capillary path, and panel alignment
Loose or spinning screw	Thread engagement, enlarged hole, substrate deterioration, incorrect screw type, insufficient length, or a missed support
Panel flutter or movement	Approved row spacing, missing fasteners, support engagement, panel span, perimeter or corner schedule, and whether the panel matches the documented assembly
Dimpled panel	Possible overdriving, uneven washer compression, or fastening in the wrong part of the profile
Crooked screw	Tool angle, screw movement during drilling, distorted hole, and incomplete washer seal
Repeated failures in one row	Mislocated support, deteriorated framing or decking, incorrect fastener specification, or a systematic layout error
Corrosion around fasteners	Fastener coating or material compatibility, environmental exposure, panel damage, and trapped moisture

It may also enter deteriorated wood, damaged decking, thin unsupported material, or a previously enlarged hole. Those conditions do not provide the connection represented by the visible pattern.

Do not solve uncertainty by adding screws

Indiscriminately adding fasteners is not an approved repair. It creates new penetrations without establishing that the new screws:

Enter sound support
Use the correct thread and material
Preserve intended panel movement
Fall within the approved roof-zone pattern
Avoid concealed building components
Remain consistent with applicable approval and warranty documents

If inadequate uplift attachment is suspected, obtain an approved repair detail rather than guessing at a denser pattern.

When can a larger replacement screw be used?

For a previously used metal-to-metal self-tapping hole, SFS gives the example of replacing a #14 Type A self-tapping screw with a one-size-wider #17 Type AB self-tapping screw so the replacement can form new threads in its metal-roof screw replacement guidance.

That is a narrow manufacturer example, not a universal repair. Do not automatically transfer it to:

Wood decking
Wood purlins
Rotten or split framing
Concrete
Enlarged holes in unsupported sheet
Clip or standing-seam attachments
An unrelated fastener system
A panel incompatible with the larger head or washer

A larger screw cannot restore a deteriorated substrate. It may create additional problems if its thread, point, washer, coating, or diameter is incompatible with the assembly.

Depending on the failure, seek guidance from the panel manufacturer, fastener manufacturer, qualified roofing contractor, or structural engineer. Manufacturer review may resolve a known panel detail; engineering review is appropriate when attachment capacity, damaged framing, high-wind exposure, or an altered structural layout is involved.

There is no universal inspection, retightening, or replacement interval for every exposed-fastener roof. Follow the system-specific maintenance documents and prioritize inspection after observed leakage, loose materials, panel movement, corrosion, impact damage, or severe-weather exposure.

The reliable method is the same for new work and repairs: identify the exact panel and substrate, locate the controlling fastening document, separate structural screws from lap screws, apply the specified pattern in each roof zone, and install every fastener straight with proper washer compression. Generic examples can help explain a drawing, but they cannot design or approve a roof.

Frequently asked questions

Is there a standard metal roof screw spacing for every panel?

No. Spacing depends on the exact panel profile, width, material, gauge, substrate, support spacing, roof geometry, roof zone, and design loads. Applicable code and permit documents, approved assemblies, engineered plans, and the manufacturer’s current instructions must be identified and reconciled.

Should metal roof screws go on the rib or in the flat?

It depends on the panel. ABM guidance places screws in the bottom flat beside the major rib, while Indiana Metal describes near-rib flat placement for the exposed-fastener applications it discusses. Some corrugated profiles accept or require high fastening. Use the exact panel diagram rather than a universal rib-or-flat rule.

Do roof edges, eaves, ridges, and panel ends need more screws?

They may require a denser or otherwise different approved pattern because attachment requirements can vary by roof zone. That does not mean every edge should receive an improvised extra row. Use the project’s zone map, approval, load table, or engineered fastening schedule.

How tight should a metal-roof screw washer be?

The washer should be compressed firmly and evenly enough to form the intended seal without bulging, splitting, crushing, or dimpling the panel. The screw must also be perpendicular and properly engaged in the intended support. An angled, underdriven, or overdriven screw can compromise the seal even when it is in the correct location.

Can I add screws or install a larger screw to fix a loose fastener?

Do not add screws indiscriminately. First determine why the original fastener is loose and whether the hole, substrate, support engagement, fastener specification, or pattern is defective.

A larger screw may be an approved repair for certain previously used metal-to-metal self-tapping holes. That approach does not automatically apply to wood, deteriorated substrates, concealed-fastener systems, or unrelated assemblies. Use a repair approved for the specific panel, fastener, substrate, and roof zone.