Coil or Strip Nails: Name the Fastener Feed in Your Roof Spec

A roofing nailer is loaded with one of two collation styles. Coil guns take nails wound into a round coil. Strip guns take nails held in a flat strip, usually by paper or plastic tape. In the box the nails look nearly the same, so the difference only shows when the crew opens the gun. A spec that says only roofing nails leaves the choice to whoever loads the gun that morning, and a homeowner standing in the driveway has no way to check it.

The reason this matters is that a nailer is built for one collation. A coil gun will not feed strip nails, and a strip gun will not feed coil nails. Crews often carry both guns on the same truck, and a job can switch between them when a battery dies, a gun jams, or a second person joins the crew partway through a slope. Nothing about a switch like that looks wrong from the ground. The shingle still goes down, the nails still go in, and the roof looks finished.

Material and spec

A complete nailing line in a shingle spec names four things: the fastener type, the head diameter, the shank, and the length. The collation belongs in that same line. A line such as coil roofing nails, correct length to reach the deck and the penetration the shingle manufacturer requires, matched to the crew's coil nailer tells the crew what to load and tells you what to check. A line that says only roofing nails does not.

The shingle manufacturer's installation instructions are the reference for the nail. They are printed on the install sheet inside the bundle and in the manufacturer's published instructions for the product. They give the fastener type, the number of nails per shingle, where the nails go relative to the cutouts and the sealant strip, and how far the nail must penetrate the sheathing. Those instructions govern the job. The spec should point to them and then name the nail that meets them, so a crew cannot satisfy the spec with a nail that is only close.

Mixed fasteners are the failure to watch for. A strip nail and a coil nail can share a gauge and a length and still differ in head shape and in how they seat when driven. A slope driven with both types looks uniform from the ground, but the seating varies from nail to nail. The problem does not usually appear on day one. It shows up later as nails that sit proud of the surface, heads that pull through the mat under wind load, or a patch of shingles that lifts first in a spring storm. In St. Louis, where spring and summer storms bring hard wind and hail, a slope with one named fastener is much easier to explain to anyone who inspects it later than a slope with two.

The gun setting is the other half of the same problem. A gun set too high drives the head through the shingle mat, and the mat is the part that keeps the shingle flat and sealed. Overdriving is covered on its own on this site, but the fix starts in the spec. Name the gun model along with the nail, so the crew has one tool it has already set for that exact nail. When the gun changes, the setting has to be checked again, and a spec that names the gun gives you a reason to ask whether it changed.

Underlayment and edge metal bring their own fasteners. Cap nails or staples at the underlayment, nails in drip edge, and fasteners in step flashing and valley metal often come from a different box and sometimes a different gun. Each of them should have its own line in the spec. If one line reads roofing nails and covers all of these, the crew will use whatever is on hand for the flashing, and the flashing is where a leak is easiest to start.

What it costs

Coil and strip nails are both sold by the box, and the difference in box price is usually small. The real cost of a mismatch is not the nails themselves. It is the crew called back to pull and reset fasteners on a slope that was already finished, the time the foreman spends walking the roof to find which nails are wrong, and the disruption of re-sealing a slope that may have been cleared of its sealant strip during the first pass.

Most bids do not show the fastener as its own line. Nails tend to disappear inside a general materials figure or inside the shingle price. A separate line for the nail, with its type and collation, lets you compare two bids on the same fastener instead of guessing what each roofer assumed. If two bids differ and the difference is in the materials total, ask which one includes the coil or strip nail, the cap nails, and the flashing fasteners, and whether each is priced at all.

Naming the collation in the spec usually adds little to the material line. It adds a few minutes at the start of the job, when the lead checks the box label against the spec and confirms the gun on the roof is loaded with the matching strip or coil. That check costs far less than tearing a slope back to the deck.

What to ask

Put these questions to each roofer in writing before you sign:

• Which fastener does the spec name for the shingles, including the type, head size, shank, and length?
• Is it a coil nail or a strip nail, and which nailer model will be loaded with it?
• Does the crew carry a second gun for the underlayment or the edge metal, and if so, which fastener does that gun take?
• Will the box label be photographed and sent to you before the first course goes down, so you can compare it to the spec?
• Who checks the nailing on the first slope, and does the foreman sign off before the crew moves to the next one?
• Are cap nails, drip edge nails, and flashing fasteners each priced as their own lines?

A roofer who can answer these from the spec sheet is describing the roof you will see from the street. A roofer who answers with we use the standard nail has not made the decision yet, and that decision will be made on the ladder, where you cannot see it.

Ask for the answers before the materials are ordered, not after the crew arrives. The fastener choice ties to the gun, the gun ties to the crew, and the crew ties to the schedule. Changing any one of them on the day of the job leaves the spec behind the roof. If you have questions about how the fastener line appears in a specific bid, the Keys Roofing office can be reached at (314) 220-2333.