A shingle roof has many small decisions that stop being visible once the job is finished. The nail is one of them. From the sidewalk you cannot tell whether the shank is smooth or ringed, but the shingle maker's wind rating, the installation instructions, and how the roof holds up in a spring windstorm all depend on it. This page is for the St. Louis homeowner who has a quote in hand and wants to know what the nail line in that quote should say.
What the two shanks do
A smooth-shank nail is the plain round shaft most people picture, with a flat head. A ring-shank nail has a series of small rings pressed into the shaft along its length. Once driven, the rings grip the wood fibers of the deck and resist being pulled back out. That resistance is called withdrawal resistance, and it matters on a roof because wind does not only push shingles sideways. It lifts them, and every lift pulls on the nail.
A smooth nail holds mainly by friction and by the way the wood closes around it. In dry, dense decking it can hold well. In decking that has been wet and dried many times over the years, or in boards that have loosened, a smooth shank has less to grab. Ring-shank nails are generally the stronger choice for withdrawal, and many shingle installation instructions either call for them or call for a nail that meets a stated pull-out or wind test. Read the instructions for the product on your roof rather than relying on what a crew usually carries.
Why the wrapper matters more than the habit
Roofers develop habits. Some crews carry one nail type on every truck and use it on every job. A crew that always uses smooth nails may be following a habit that works on some shingles and not on others. The shingle wrapper and the manufacturer's installation guide are the authority here. They state the nail type, the nail length, the number of nails per shingle, and where the nails belong. A quote that says roofing nails without naming the shank is not yet a specification.
Keys installs Atlas and Malarkey shingles only, so the nail requirements that matter on a Keys job are the ones printed for those products. Ask the estimator to write the nail type on the proposal and to name the source, whether that is the installation guide or the wrapper language for the specific product going on your roof. A laminated architectural shingle and a three-tab shingle from the same manufacturer can carry different nailing instructions, so the product name alone is not enough to settle the question.
Nail length follows the deck
Length is the other half of the spec. The nail has to pass through the shingle, through the underlayment if there is any, and into the roof deck far enough to hold. Residential building codes commonly require at least three quarters of an inch of penetration into roof sheathing, and the shingle maker's instructions may ask for more. The right length depends on the thickness of the deck and of anything between the deck and the shingle, including old layers left in place where that is allowed. The proposal should state the length in inches and tie that number to the decking that was measured.
Older houses raise a different question. Plank decking is made of boards that may be narrower and less uniform than modern plywood or OSB, and a nail that reaches solid wood in one section may pass through a gap in another. If the tear-off shows loose or soft boards, the nail schedule may need to change, and the proposal should say what happens in that case rather than leaving the crew to decide on the roof.
Coil nailers and depth
Most roofers drive shingle nails with a pneumatic coil nailer. The tool sets the depth, and a properly adjusted nailer drives the head flush with the shingle without cutting through it. An over-driven nail cuts into the shingle and loses holding power. An under-driven nail stands proud of the surface, and the shingle above it may not lie flat. Both faults show up as wavy shingle rows or torn granules, and both are easier to correct on the first slope than on the last.
Ask the crew which tool they use and whether the depth is checked on the compressor or the gun at the start of each day. Ask who inspects the first squares once they are laid. None of this is a question about the crew's skill. It is a question about whether the nail the spec calls for is the nail that ends up in the roof.
Nail placement is part of the spec
Shingle wrappers also show where the nails go. Many products print a nail line on the shingle, usually high enough that the next course covers the head, and state the number of nails required per shingle. Too few nails can leave a shingle free to lift in wind. Nails set too low can be exposed by the overlap or sit where they do not match the wind rating the product was tested to. Hips and ridges often follow different placement rules from the field of the roof, so the proposal should not treat them as a single number.
Spring is when St. Louis roofs get tested most often. Straight-line wind, passing storms, and the freeze and thaw cycle that loosens fasteners over winter all put repeated stress on the nail line. A roof installed with the right shank, length, count, and placement has the best chance of riding those seasons without lifting shingles, and a roof installed with a vague nail line has no written standard to point back to when a shingle comes loose.
Corrosion and the coating
Nail material matters here for a plain reason. Roof nails sit in a humid attic below and in weather above, and the coating on the shank is what keeps it from rusting through. Rust does not show from the street, but it can weaken a nail over years. The proposal should name the nail as corrosion resistant, galvanized or otherwise coated, to the level the shingle maker requires. A nail with a thin or missing coating can look fine on installation day and still be the weak point in the roof a decade later.
Nail cost is usually a small part of a shingle job, and the difference between a ring-shank and a smooth nail is generally small compared with labor. That makes the nail easy to hide inside a bundle figure or a general materials line. Ask for it to be listed separately so you can see what you are paying for and compare it directly with another quote.
What to ask before the nails go in
- Which shank does the proposal call for, smooth or ring, and does it cite the wrapper or the installation guide for the shingle on this roof?
- How long is the nail, and how does that length reach solid sheathing on your deck once any underlayment and existing layers are counted?
- How many nails go into each shingle, and where in the nail line do they go on the field, the hips, and the ridge?
- Is the nail galvanized or otherwise coated, and does the proposal name that coating?
- Who sets the depth on the coil nailer, and who checks the first slope before the crew continues?
- If the deck is older plank or has loose sections, does the nail schedule change, and does the proposal say what happens when a board will not hold a nail?
Where the spec goes in writing
The proposal should not stop at the word nails. Keys can put the nail type, the length, the count per shingle, and the placement into the written scope, along with the photos and measurements that show the deck and the first installed courses. You keep that document. It is your record of what was specified for the roof, and it is the thing to compare against the finished work.
If another quote lists the same shingle and says roofing nails only, ask that roofer for the nail type and length in writing. A difference in the nail line is a difference in the spec, even when the shingle name matches on both quotes. The right time to find that difference is before the first nail is driven, not after the first high wind.