High Nailing: The Defect That Voids Shingle Warranties
There is a narrow band across every asphalt shingle where the nails are supposed to go. It is marked on the shingle. Put the nails above it and the roof looks completely normal, passes a casual glance, and will shed shingles in a wind event years later.
This is called high nailing, and it is the most common installation defect in residential roofing. It is also close to invisible once the next course is laid, which is exactly why it persists.
Why the nail line matters
An asphalt shingle is held down twice. The nails fasten it to the deck, and a strip of factory-applied adhesive bonds it to the shingle below once the sun warms it. Both have to work.
The correct nail placement does two things at once. It passes through the thick reinforced part of the shingle, and it lands where the next course above will cover it. Critically, on laminated architectural shingles, it also passes through both layers of the shingle where they overlap, the common bond area.
Nail too high and three things go wrong simultaneously:
- The nail only catches the top single layer, so the lower half of the shingle is held on by adhesive alone.
- The nail head may sit above the coverage line of the course above, leaving it exposed to water.
- The shingle can flex and pivot at the fastener, working the adhesive bond loose over time.
The result is a roof that looks perfect for several years and then loses shingles in a storm that should not have troubled it.
The other side of the same problem
Nails driven too low are also a defect, because they end up exposed below the course above. And nails driven at an angle, overdriven so they cut into the mat, or underdriven so the head stands proud, all fail in their own ways. Overdriven nails are particularly common with pneumatic guns set too high.
Why it happens
Speed, almost entirely. Nailing higher on the shingle means less bending down and a faster rhythm across the roof. On piecework it adds up. It is not usually malice; it is a crew moving quickly without close supervision.
It is also self-concealing in a way few other defects are. Once the course above is laid, nobody can see where the nails went without lifting shingles. A homeowner walking the finished roof cannot detect it. Neither can a buyer, or a home inspector doing a visual survey.
The warranty consequence
This is the part worth understanding. Manufacturer warranties cover material defects, not installation defects. Fastening outside the specified nail zone is an installation defect, and where a manufacturer investigates a claim and finds high nailing, the material warranty typically will not respond.
So you fall back on the contractor workmanship warranty: which means you are relying on that company still existing, still standing behind it, and agreeing that the nailing was wrong. Specific terms vary by manufacturer and by contractor, so read both documents, but the general shape holds: high nailing moves the risk from the manufacturer onto you.
How to catch it
Before and during the work, not after:
- Ask which nail pattern is specified and how many nails per shingle. Four is common; six is required in high-wind applications and by some manufacturers for enhanced warranties. A contractor who knows the answer immediately is a good sign.
- Go outside while the roof is being installed. You do not need to climb anything. Watch a course go on from the ground with binoculars if you like. You are looking for a consistent line, not perfection.
- Ask to see a photo of an installed course before the next one covers it. Any competent crew can produce this, and asking signals that you know the detail exists.
- Keep a shingle wrapper. The nailing specification is printed on the bundle wrapper. It is the manufacturer telling you what was required, in writing, for free.
- If a permit inspection is happening, do not skip it. An inspector arriving mid-installation is one of the few people who can see nail placement at the right moment.
If you suspect it on an existing roof
It can be confirmed, but only by lifting shingles in a few places to look at the fasteners. That is a small, repairable intrusion and it is the only reliable method. A roof losing shingles in ordinary wind, or showing shingles that lift easily by hand along a course, is worth investigating.
The remedy depends on extent. Isolated areas can be refastened. Widespread high nailing on a young roof is a conversation with the installing contractor before it is a repair.
Our roof inspection process includes checking fastening where shingles can be lifted without damage, and our roofing repair team handles refastening. If you are comparing quotes, nail count and pattern is one of the questions in how to read a roofing estimate, a vague answer there is informative.
High nailing questions
Driving the fasteners above the manufacturer’s specified nail zone on a shingle. The roof looks normal, but the nails miss the reinforced double-layer area, leave the lower part of the shingle held by adhesive alone, and can end up exposed above the coverage line of the course above.
You generally cannot tell by looking. Confirming it means lifting shingles in a few places to see where the fasteners sit. Suggestive signs are shingles lost in ordinary wind, or shingles along a course that lift easily by hand.
It typically prevents a manufacturer material warranty from responding, because fastening outside the specified zone is an installation defect rather than a material defect. That leaves the contractor workmanship warranty, whose value depends on that company still being around. Terms vary, so read both documents.
Four is the common standard, and six is required for high-wind applications and by some manufacturers for enhanced warranty coverage. The requirement is printed on the shingle bundle wrapper, which is worth keeping.
Isolated areas can be refastened. Widespread high nailing on a relatively new roof is really a matter to raise with the installing contractor first, because the cost of correcting it across a whole roof approaches the cost of doing it again.
Speed. Nailing higher on the shingle is a faster, less awkward motion, and across a whole roof it saves real time. Because the next course hides the evidence immediately, there is no visible consequence at the time.