By The Roofing Brief Team | Last reviewed: October 2026
The right nails for flashing are made of the same metal as the flashing, or of a metal that sits next to it on the galvanic scale: copper, brass, bronze or 300-series stainless steel for copper; aluminum or stainless for aluminum; hot-dip galvanized for galvanized steel. On a shingle roof, drip edge must also be fastened with code roofing nails (2021 IRC R905.2.5 and R905.2.8.5: 12-gage shank minimum, 3/8-inch head, no more than 12 inches apart). Where you nail matters as much as what you nail with: step flashing gets nailed to the roof deck only, never the wall.
This page covers fastener choice and placement for flashing metal. For shingle nail lengths and the four-versus-six nail rule, see our roofing nail sizes and code guide. For the full sidewall sequence, see our step flashing installation guide.
Key numbers at a glance
These are the fastener figures most people searching for nails for flashing need. Each comes from a named code section, trade association handbook or manufacturer instruction. Local codes and the shingle maker’s instructions can be stricter, so treat these as the baseline.
| Item | Figure | Source |
|---|---|---|
| Minimum roofing nail for shingles and drip edge | 12-gage (0.105 in) shank, 3/8 in head, ASTM F1667, 3/4 in into the deck or through it | 2021 IRC R905.2.5, R905.2.8.5 |
| Drip edge fastener spacing | Not more than 12 in on center | 2021 IRC R905.2.8.5 |
| Minimum flashing metal thickness | 0.019 in (No. 26 galvanized sheet) | 2021 IRC R903.2.1 |
| Copper nails for copper work | Flathead slating nail, at least 1 in long, 12 gauge or heavier hard copper, brass or bronze; barbed in wood | CDA Copper in Architecture Design Handbook, sec. 7.1 |
| Nail spacing on copper edge strips and base flashing | No more than 3 in on center, one edge only | CDA handbook, sec. 7.1 |
| Step flashing nails | 1 nail in the top 2 in of the roof leg (CertainTeed) or 2 nails in the roof flange (Owens Corning); none in the wall leg | CertainTeed Shingle Applicator’s Manual, ch. 6; Owens Corning Roofer’s Guide |
What kind of nails do you use for flashing? Match the metal
Use a nail that is the same metal as the flashing, or one the flashing metal’s own trade association lists as compatible. The Copper Development Association (CDA) says fasteners for copper should be copper, brass, bronze or a neutral stainless alloy. The Aluminum Association permits aluminum, 300-series stainless and galvanized steel against aluminum. The 2021 IRC names galvanized fasteners for steel and stainless for any metal roof.
The table below is the metal by fastener compatibility matrix. “Use” is the matched choice. “Also acceptable” is what the cited source allows. “Avoid” is the combination that source warns against.
| Flashing metal | Use | Also acceptable | Avoid | Source |
|---|---|---|---|---|
| Copper (16 oz or heavier) | Copper slating or roofing nails | Brass, bronze, 300-series stainless nails or screws; copper or stainless cleats | Galvanized, zinc-coated, aluminum and plain steel nails | CDA handbook sec. 1.3 and 7.1; 2021 IRC R905.10.4 |
| Aluminum (mill or painted) | Aluminum roofing nails | 300-series stainless (not in high-chloride settings without isolation); hot-dip galvanized | Copper, brass and bronze nails; bare carbon steel; copper runoff | Aluminum Association, Aluminum Design Manual sec. 6.7 |
| Galvanized steel (G90) | Hot-dip galvanized roofing nails | Stainless steel fasteners (2021 IRC); aluminum nails (ADM sec. 6.7.1) | Copper, brass and bronze nails | 2021 IRC R905.10.4; American Galvanizers Association |
| Galvalume or painted metallic-coated steel trim | The panel maker’s zinc-coated or zinc-aluminum capped fasteners | 300-series stainless rivets (AEP Span standard) | Copper in contact or upslope; stainless hardware in corrosive coastal exposure, per AEP Span | AEP Span Dissimilar Metals Fastener Guide and Technical Bulletin |
| Stainless steel | Stainless nails, screws or rivets | Copper (CDA: isolation between copper and stainless is not needed under most circumstances) | Galvanized and aluminum fasteners | 2021 IRC R905.10.4; CDA sec. 1.3; American Galvanizers Association |
| Lead | Copper nails | Stainless nails | Aluminum and galvanized nails | Roofing Brief reading of CDA Table 1.3A (lead sits next to copper) |
Two sources disagree on one cell, and it matters for coastal jobs. The Aluminum Design Manual allows hot-dip galvanized steel against aluminum without paint, but AEP Span tells buyers of its aluminum panels that galvanized accessories of any kind cause dissimilar metal problems and to use stainless instead. Stainless is the one choice both accept, so it is the conservative pick for aluminum flashing near salt air.
Why the wrong nail eats the flashing: galvanic corrosion rules
When two different metals touch and water bridges them, the less noble metal corrodes and protects the more noble one. The CDA ranks common building metals from least to most noble as aluminum, zinc, steel, iron, active stainless, tin, lead, copper and passive stainless. Copper is not harmed by any of the metals below it, but it attacks them, and aluminum and zinc are the CDA’s main concern.
- Only the lower metal corrodes. A galvanized nail in copper flashing loses its zinc and then rusts; the copper is fine. That is why a leak from a mismatched nail usually starts at the nail hole, not in the open sheet. For how those failures get fixed on a copper roof, see our guide to copper roof repair by failure.
- Size ratio decides speed. The American Galvanizers Association recommends at least 10 times more zinc surface than the more noble metal it touches. A 3/8-inch nail head has about 0.11 square inch of area; a 10 by 7 inch step flashing piece has 70. That is roughly a 630 to 1 ratio in the wrong direction when the nail is the zinc part (Roofing Brief arithmetic).
- Runoff counts as contact. The CDA says wash from copper must not drain onto exposed aluminum, and the Aluminum Design Manual (sec. 6.7.4) says aluminum shall not be exposed to water that has touched copper. AEP Span adds that unpainted galvanized steel must not catch runoff from Galvalume or more noble metals.
- Treated lumber is a metal source too. AEP Span warns that copper leaching from copper-treated lumber can corrode coated steel without direct metal contact. The 2021 IRC R317.3.1 lists hot-dip galvanized, stainless, silicon bronze and copper fasteners for preservative-treated wood; aluminum is not on that list.
- Isolation is the fix when you cannot match. The CDA lists bituminous paint, zinc chromate primer, nonabsorptive tape, gaskets and sealants as separators, and says lead gaskets should not be used between copper and aluminum.
The common forum claim that a mismatched pair “corrodes both metals” is not what the CDA describes. One metal is sacrificed. Knowing which one tells you where to look for failure on an existing roof.
Nail types for flashing: what each one is for
Flashing nails differ by metal, shank and head. A ring-shank grips wood harder than a smooth shank, a 3/8-inch head is the IRC minimum where a roofing nail is required, and copper nails run thicker than steel to make up for softer metal. The specifications below come from the makers’ own product pages and the cited handbooks.
| Fastener | Typical spec | Best for | Watch out for | Source |
|---|---|---|---|---|
| Copper ring-shank slating and flashing nail | 0.135 in (10 ga) shank, 0.375 in head, 3/4 to 3 in lengths | Copper flashing, slate, tile | Soft; predrill hard decks. CDA wants barbed shanks in wood | Maze Nails product page; CDA sec. 7.1 |
| Stainless 304 ring-shank roofing nail | 11 ga, 0.375 in head, 1 to 1-1/2 in | Copper, stainless or aluminum flashing; coastal work | AEP Span cautions on stainless in coated steel near the coast | Maze Nails roof flashing category |
| Aluminum roofing nail | 11 ga, 0.375 in head, 1-1/2 in (Maze AS4, 5056 alloy) | Aluminum drip edge, step and apron flashing | Bends in dense decks; not listed for treated wood in IRC R317.3.1 | Maze Nails roof flashing category |
| Hot-dip galvanized roofing nail | 11 ga, 0.375 in head, 7/8 to 1-3/4 in, smooth, ring or spiral | Galvanized steel flashing, shingles | Never in copper; zinc coating weights per ASTM A153 | Maze Nails; 2021 IRC R317.3 |
| Aluminum or stainless trim nail | Small head, made to sit flush on trim | Fascia and trim coil, not roof flashing | Smaller than a 3/8 in head fails the R905.2.5 nail that drip edge requires | 2021 IRC R905.2.5, R905.2.8.5 |
| Cleat | 16 oz copper or compatible stainless, set at 12 in on center | Copper valleys, counterflashing, edge strips that must move | Fasten the cleat, not the sheet: two compatible nails or screws per cleat | CDA sec. 7.1 and details 9.2, 9.5 |
| Rivet | Solid copper (tinner’s) rivets for copper; 1/8 in 300-series stainless pop rivets on coated steel trim | Lap seams that need strength, usually soldered on copper | Rivet metal must match the sheet like a nail | CDA guide specifications; AEP Span fastener guide |
Every Maze roof flashing nail listed above carries a 0.375-inch head, which matches the code minimum for shingle work. If a box only says “flashing and trim,” read the head diameter before it goes on a roof. If you run a coil nailer for the shingles, our guide to collated roofing nails compares electro-galvanized, hot-dip and stainless coils.
Where to nail flashing, and where never to
Nail flashing to the roof deck on the side the shingles cover, and leave the wall side free. Roofs and walls move at different rates, and a nail through the wall leg ties them together, tears the seal and leaves an exposed hole. Counter flashing is held by the wall itself, and valley metal is held at its edges or by cleats so no nail punctures the water path.
| Flashing piece | Fasten here | Spacing | Never | Source |
|---|---|---|---|---|
| Step flashing | Roof leg, high corner, in the top 2 in | 1 nail per piece (CertainTeed) or 2 (Owens Corning) | Nail the wall leg; nail siding through the vertical leg | CertainTeed manual ch. 6; Owens Corning Roofer’s Guide |
| Counter (cap) flashing on masonry | Bent edge into a mortar joint raked 1-1/2 in deep and refilled, or a reglet with lead wedges and sealant | Continuous | Fasten to the roof deck or to the step flashing | Owens Corning Roofer’s Guide; CDA detail 9.8; CertainTeed manual ch. 6 |
| Apron or headwall flashing | Roof leg, set in roof cement over the last course | Per shingle maker | Nail the wall leg; leave exposed nails without neoprene washers | Owens Corning Roofer’s Guide |
| Drip edge | Horizontal leg into the deck | 12 in on center max; NRCA suggests slightly staggered and closer in high wind | Use nails below the R905.2.5 spec | 2021 IRC R905.2.8.5; NRCA via Professional Roofing, Jan. 2010 |
| Open valley metal | Outer edges only, without puncturing the valley | 8 to 12 in apart | Nail near the center of the valley | Owens Corning Roofer’s Guide |
| Copper valley sheets | Cleats along the sides, nails at the top only | Cleats 12 in on center | Nail through the field of the sheet | CDA detail 9.5 |
| Copper edge strips and base flashing | One edge only | No more than 3 in on center | Nail both edges (blocks thermal movement) | CDA sec. 7.1 |
| Copper counterflashing on sheathing | Cleats, or wide-head nails driven just above the top edge so the head holds the sheet | Cleats 12 in on center; CDA details show nails at 3 to 4 in | Drive nails through the copper | CDA sec. 9.1 and detail 9.2A |
CertainTeed’s manual puts it plainly: do not fasten the cap flashing to the roof deck or the step flashing, because they need to move independently. Owens Corning says the same about the wall: do not nail flashing to the wall, as differential movement of the wall and roof could damage the seal.
What the code says about flashing fasteners
The 2021 International Residential Code sets flashing metal thickness and drip edge nailing, and hands most other flashing details to the shingle maker’s instructions. It does not prescribe a nail for step flashing, and it does not mention a reglet. Those details come from manufacturer guides and the CDA, which is why the manufacturer instructions carry so much weight here.
- R903.2.1: metal flashing “shall be corrosion resistant with a thickness of not less than 0.019 inch (0.5 mm) (No. 26 galvanized sheet).”
- R905.2.8.3 Sidewall flashing: “Base flashing against a vertical sidewall shall be continuous or step flashing and shall be not less than 4 inches (102 mm) in height and 4 inches (102 mm) in width.” Where anchored masonry veneer is on the wall, counterflashing is required by cross-reference to Section R703.8.2.2.
- R905.2.8.4 Other flashing: front wall, soil stack, vent pipe and chimney flashing “shall be applied in accordance with the asphalt shingle manufacturer’s printed instructions.”
- R905.2.8.5 Drip edge: “mechanically fastened to the roof deck at not more than 12 inches (305 mm) o.c. with fasteners as specified in Section R905.2.5.”
- R905.10.4 Metal roof panels: absent manufacturer instructions, galvanized fasteners for steel roofs; “copper, brass, bronze, copper alloy and 300-series stainless steel fasteners” for copper roofs; stainless acceptable for metal roofs.
The 2021 text allows continuous base flashing at a sidewall as well as step flashing, so a claim that continuous sidewall flashing violates the code is quoting an older edition or a manufacturer rule. CertainTeed and Owens Corning both call for step flashing at sidewalls, and R905.2.8 makes the shingle maker’s approved instructions part of the requirement. Check which IRC edition your jurisdiction adopted.
Sealant at fasteners: when it helps and when it hides a mistake
Sealant belongs on any nail head left exposed to weather and in the reglet above counter flashing, not as a substitute for a compatible nail in the right place. Owens Corning calls for neoprene washers on exposed headwall flashing nails. The CDA calls for reglets filled with sealant over lead wedges.
Sealant chemistry matters on copper. The CDA reports good results from elastomeric polyurethane, silicone, butyl and polysulfide sealants, and says acrylic, neoprene and nitrile based sealants have been observed to corrode copper, so it does not recommend them. A dab of sealant over a galvanized nail in copper flashing does not stop galvanic corrosion; it hides it until the flashing leaks.
How to choose and drive nails for flashing
- Identify the flashing metal. Copper is reddish or brown to green, aluminum is light and non-magnetic, galvanized and Galvalume steel are magnetic. A magnet separates steel from aluminum in seconds.
- Pick the nail metal from the compatibility table. Match it, or use a fastener the cited source lists as compatible. Near salt air, check the panel or trim maker’s own guide before using stainless in coated steel.
- Check the head and shank. Where a roofing nail is required, use a 3/8-inch head and a 12-gage or heavier shank that meets ASTM F1667. For copper, CDA wants 12 gauge or heavier and at least 1 inch long.
- Size the length. The nail has to pass through the flashing, shingle and underlayment and reach 3/4 inch into the deck, or through a thinner deck, under 2021 IRC R905.2.5.
- Nail only the roof side. Step flashing goes in the high corner of the roof leg. Apron and headwall flashing get nailed to the roof, not the wall. Valley metal is held at its edges or with cleats.
- Drive flush, not deep. An overdriven head can dent thin flashing and open a path for water; an underdriven head can lift the shingle above it.
- Cover or seal every exposed head. Let the next shingle course cover the nail, or use a neoprene washer or a sealant compatible with the flashing metal.
Which nail should you pick? Quick decision table
Use this table when you are standing at the supply counter. Each recommendation follows from the compatibility and placement tables above.
| Your situation | Pick |
|---|---|
| Aluminum drip edge or step flashing on an asphalt shingle roof, inland | Aluminum roofing nails with a 3/8 in head, or stainless roofing nails |
| Aluminum flashing within sight of salt water | Stainless roofing nails, and check the flashing maker’s guidance |
| Galvanized steel step flashing or drip edge | Hot-dip galvanized roofing nails, the same type used for the shingles |
| Copper chimney or sidewall flashing | Copper slating nails (barbed or ring-shank in wood), or 300-series stainless |
| Copper valley or long copper edge strip | Copper cleats at 12 in on center; nail one edge only at 3 in on center |
| Flashing nailed into pressure-treated blocking | Hot-dip galvanized, stainless or copper per IRC R317.3.1, matched to the flashing metal |
| Painted or Galvalume metal roof trim | The panel maker’s listed fasteners; do not mix in copper |
| Small aluminum trim nails already in hand | Fine for fascia trim coil; not for drip edge on a shingle roof |
Worked example: how many flashing nails a typical job uses
Flashing nail counts are small, which is why paying for the matched metal rarely changes the job price much. These are Roofing Brief estimates built only from the spacing rules cited above; real counts vary with laps, corners and the shingle exposure.
- Sidewall step flashing, 12 ft along the slope, 5 in shingle exposure: 144 in divided by 5 in is 28.8, so 29 pieces. At CertainTeed’s one nail per piece that is 29 nails; at Owens Corning’s two per flange it is 58.
- Drip edge, 40 ft of eave at 12 in on center: 40 spaces plus the end nail is 41 nails before laps, more if you stagger or tighten spacing for high wind as NRCA suggests.
- Copper edge strip, 20 ft at the CDA’s 3 in maximum: 80 spaces plus one is 81 nails, four times what the same run takes at 12 in. Copper work uses more nails per foot, so buy copper nails by the pound, not by the handful.
Flashing labor and metal, not nails, drive cost. For what a full chimney job runs, see our chimney flashing replacement cost breakdown. For how flashing pieces fit together across a roof, see our roof flashing guide, and for the masonry side, our counter flashing guide.
Frequently asked questions
What kind of nails do you use for flashing?
Use a nail made of the same metal as the flashing, or a compatible one. Copper flashing takes copper, brass, bronze or 300-series stainless nails. Aluminum flashing takes aluminum or stainless nails. Galvanized steel flashing takes hot-dip galvanized nails. Where the flashing is a drip edge on a shingle roof, the 2021 IRC also requires a roofing nail with at least a 12-gage shank and a 3/8-inch head.
What type of nails should I use with aluminum flashing?
Aluminum roofing nails are the matched choice, and 300-series stainless steel nails are the safest alternative. The Aluminum Association’s Aluminum Design Manual says hot-dip galvanized steel and 300-series stainless can touch aluminum without paint, except stainless in high-chloride settings. Never use copper, brass or bronze nails in aluminum, and keep copper roof runoff off aluminum flashing.
Should flashing be nailed down?
Yes, but only on the roof side and only as much as the manufacturer calls for. CertainTeed says to fasten step flashing to the roof with one nail in the top 2 inches; Owens Corning shows two nails in the roof flange. Neither nails the wall leg. Counter flashing locks into the masonry joint or reglet and is never nailed to the step flashing below it.
What do you use to attach flashing?
Most residential flashing is attached with compatible roofing nails. Copper work also uses cleats, which the Copper Development Association shows at 12 inches on center, plus solid copper rivets and solder at seams. Counter flashing on masonry is held in a reglet with lead wedges and sealant, or in a raked mortar joint refilled with mortar. Metal panel trim often uses gasketed screws or stainless rivets.
Can you use galvanized nails with copper flashing?
No. The Copper Development Association ranks zinc well below copper in nobility, so a zinc-coated nail in copper flashing corrodes at the contact point. The American Galvanizers Association also warns against galvanized fasteners joining copper or stainless parts. Use copper, brass, bronze or 300-series stainless nails, which is the same list the 2021 IRC gives for copper metal roofs in Section R905.10.4.
Why do roofers use copper nails?
Roofers use copper nails because they match copper flashing and are the standard fastener for slate and many tile roofs. Copper does not rust, and the Copper Development Association calls for flathead copper, brass or bronze slating nails at least 1 inch long and 12 gauge or heavier. Maze Nails describes its solid copper nails as the type many tile and slate brands recommend and the most compatible nail for copper flashing.
Can I use trim nails on roof flashing?
On drip edge, usually not. The 2021 IRC says drip edge must be fastened with the roofing nails described in Section R905.2.5, which means at least a 12-gage shank and a 3/8-inch head. Many aluminum or stainless trim nails have smaller heads made to hide in trim. Check the head size on the box before using them anywhere the code or the shingle maker specifies a roofing nail.
Sources
- International Code Council, 2021 International Residential Code, Sections R317.3, R903.2, R903.2.1, R905.2.5, R905.2.8.3, R905.2.8.4, R905.2.8.5 and R905.10.4.
- Copper Development Association, Copper in Architecture Design Handbook, Publication A4050 (8/24): sec. 1.3 (galvanic action, Table 1.3A), sec. 7.1 (attachments), sec. 9 (flashings and copings).
- The Aluminum Association, Aluminum Design Manual (2005 edition), Specification sec. 6.7, Contact with Dissimilar Materials.
- American Galvanizers Association, Dissimilar Metals in Contact (galvanizeit.org).
- AEP Span, Dissimilar Metals Fastener Guide and Technical Bulletin (2021).
- CertainTeed, Shingle Applicator’s Manual, chapter 6, flashing against a sidewall.
- Owens Corning, Roofer’s Guide to Roof Installation (2015): step, front wall, valley and chimney flashing.
- Professional Roofing, “Focusing on fasteners,” Joan P. Crowe, January 2010 (NRCA drip edge guidance).
- Maze Nails, roof flashing nail product pages (copper, stainless, aluminum and hot-dip galvanized specifications).