How many screws for metal roofing you need works out to roughly 80 screws per roofing square (100 square feet) on a standard exposed-fastener panel, which is about 20 to 30 screws per 3-foot-wide panel. Standing seam roofs fasten differently, using 12 to 16 concealed clips per panel instead of exposed field screws. The real count shifts with panel profile, row spacing, and how much you tighten fastening at the eaves, rakes, and corners.
How many screws per square of metal roofing?
Plan on about 80 screws per square of metal roofing, where one square equals 100 square feet. That number covers the field screws plus the lap and stitch screws you need on a typical exposed-fastener panel. Multiply your total squares by 80 for a fast field estimate.
Published figures range from as low as 20 to as high as 100 screws per square, and the spread is the reason so many first-time buyers order the wrong quantity. A count near 20 usually reflects only one screw line down a wide panel with no lap or trim screws added. A realistic installed count, field plus laps plus trim tie-ins, lands closer to 75 to 100 per square. Panel width and rib spacing move the number inside that band.
How many screws per sheet by panel type?
An exposed-fastener panel takes roughly 20 to 30 screws per sheet, assuming a 36-inch-wide panel about 12 feet long with screw rows every 24 inches. Standing seam is the exception: its panels lock together over concealed clips, so a panel uses 12 to 16 clip fasteners and no exposed field screws at all.
| Panel profile | Panel width | Fasteners per panel | Fastening method |
|---|---|---|---|
| Corrugated (7/8 in) | ~37 to 39 in | 20 to 30 screws | Exposed, every third corrugation, rows 24 in o.c. |
| R-Panel / PBR | 36 in | 20 to 30 screws | Exposed, in the flat beside each major rib, rows 24 in o.c. |
| 5-rib / Western Rib (7.2) | 36 in | 25 to 40 screws | Exposed, beside every rib, rows 24 in o.c. |
| Standing seam | 12 to 19 in | 12 to 16 clips | Concealed clips, no exposed field screws |
Panel counts assume a 12-foot panel. A longer run adds one more screw row for every additional 24 inches of length, so a 16-foot panel carries roughly a third more field screws than a 12-foot one.
What screw spacing produces that count?
The count comes straight out of two spacing rules: screw rows run every 24 inches down the panel, and within each row you fasten either every rib or every other rib depending on the profile and the manufacturer’s schedule. Multiply the number of rows by the screws per row and you have the panel count.
On a 12-foot panel that is a row at the eave, three intermediate rows, and a row at the ridge, so five rows. A 5-rib panel fastened beside every rib puts about 5 to 6 screws in each row, which is where the 25 to 40 per panel figure comes from. This guide answers how many screws you need; for the separate debate over screwing the raised rib versus the flat pan and the exact placement pattern, see our guide on where to place metal roofing screws.
How to calculate total screws for your whole roof
To size a full order, convert roof area to squares, apply the 80-per-square rule, add trim screws by the lineal foot, then pad for edge zones and waste. The steps below give a defensible number before you buy.
- Measure total roof area and divide by 100 to get squares. A 1,600-square-foot roof is 16 squares.
- Multiply squares by 80 for combined field and lap screws: 16 x 80 = 1,280 screws.
- Add one lap or stitch screw per lineal foot of trim and flashing at eaves, rakes, ridge, hips, and valleys. Roughly 180 lineal feet adds 180 screws.
- Increase fastening density in perimeter and corner zones for wind uplift (covered below).
- Add 10 to 15 percent for waste, stripped screws, and cut panels, then round up to full boxes.
| Step | Screws |
|---|---|
| Field + lap (16 squares x 80) | 1,280 |
| Trim and flashing (180 lin ft) | 180 |
| Subtotal | 1,460 |
| Add 12 percent waste | ~1,635 |
Screws are commonly boxed in 250 counts, so this roof needs about seven boxes. A metal roofing calculator can cross-check the panel and screw totals against your exact coverage width.
Add screws at edges, corners, and high-wind zones
Roof edges and corners take far more wind uplift than the field, so most engineered fastening schedules tighten screw spacing in those zones. Skipping this step is a common reason panels peel at the eave in a storm even when the field is fastened correctly.
Wind design under ASCE 7 divides a roof into field, perimeter, and corner zones, with the corner zone carrying the highest uplift pressure. In practice, manufacturers often call for reduced row spacing (12 inches on center instead of 24) or fastening every rib rather than every other rib within the perimeter and corner zones. The exact zone width and spacing depend on building height, roof pitch, and your local wind speed, so follow the panel maker’s engineered schedule and your local building code rather than a single national rule.
Trim, lap, and stitch screws people forget
Beyond field screws, a metal roof needs lap and stitch screws at every seam and trim piece, roughly one per lineal foot. These are the fasteners most homeowners leave out of a screw count, and running short mid-install stalls the job.
- Panel sidelaps: stitch screws join panel to panel along the overlapping rib, sealing the seam.
- Endlaps: where one panel overlaps another end to end, screws pull the lap tight over sealant tape.
- Trim and flashing: ridge cap, eave trim, rake trim, and valley metal each take lap screws about every 12 to 18 inches.
Field screws for panel-to-wood usually run 1 to 1.5 inches long with a bonded EPDM washer, while stitch screws are shorter, self-drilling, metal-to-metal fasteners. Order both. For the full fastening sequence in context, see our metal roof installation guide and the profile-specific notes in our corrugated metal roofing guide. More background sits in our learn about roofing hub.
Frequently asked questions
How many screws per square of metal roofing?
Roughly 80 screws per square, where one square is 100 square feet. That figure includes field screws plus lap and stitch screws on a standard exposed-fastener panel. Counts published as low as 20 usually count only a single screw line, while installed totals with laps and trim generally land between 75 and 100 per square depending on panel width and rib spacing.
How many screws per sheet of metal roofing?
An exposed-fastener panel takes about 20 to 30 screws per sheet, based on a 36-inch-wide, 12-foot panel with screw rows every 24 inches. A 5-rib profile fastened beside every rib can reach 40. Standing seam is different: its panels use 12 to 16 concealed clips per panel and no exposed field screws.
How far apart should metal roofing screws be?
Screw rows typically run 24 inches on center down the panel, and within each row you fasten every rib or every other rib depending on the profile. In perimeter and corner zones exposed to higher wind uplift, spacing often tightens to 12 inches on center. Always follow the panel manufacturer’s engineered fastening schedule and local code.
Do you screw metal roofing on the rib or the flat?
It depends on the panel. Exposed-fastener panels like R-Panel and PBR are usually screwed in the flat pan beside each rib, while corrugated and some rib panels are fastened on or beside the crown. Placement affects both watertightness and holding strength, and the right answer follows the manufacturer’s spec for that profile.
Can you use too many screws on a metal roof?
Yes. Over-fastening adds cost and stresses the panel, and over-driving any single screw distorts the rubber washer, which then leaks. Under-driving leaves a gap that lets water in. The goal is the specified count driven to a snug, compressed washer that sits flat, not crushed and not proud of the metal.
What size screws do you use for metal roofing?
Panel-to-wood screws usually run 1 to 1.5 inches long, sized to bite at least 1 inch into solid decking or purlin, with a bonded EPDM washer for sealing. Thicker substrates or wood battens call for longer screws. Stitch screws for panel-to-panel laps are shorter, self-drilling, metal-to-metal fasteners.
Reviewed by The Roofing Brief Team. Last reviewed July 2026.