Kentucky Roof Code · Fastening
Shingle nailing code in Kentucky sets a floor of four fasteners per strip shingle — and then immediately defers to something stricter. The section says the shingles “shall have the minimum number of fasteners required by the manufacturer,” so the number on the wrapper, not the number in the code, is usually the one that governs the job.
Is it four nails or six nails per shingle?
Four is the code minimum per strip shingle. Six is common because the shingle manufacturer requires it, and the code adopts whatever the manufacturer requires.
Section R905.2.6 of the residential code is one sentence long and does both jobs at once: asphalt shingles “shall have the minimum number of fasteners required by the manufacturer, but not less than four fasteners per strip shingle or two fasteners per individual shingle.” Kentucky adopts the 2015 International Residential Code with state amendments, published by the Department of Housing, Buildings and Construction as the Kentucky Residential Code; the section text can be read in the Kentucky roof assemblies chapter.
So “the code only says four” is half a sentence. If the installation instructions in the bundle call for six in a high-wind application, six is the code requirement on that roof, because the code wrote the manufacturer’s number into itself.
One more case sits in the same sentence: where the roof slope exceeds 21 units vertical in 12 horizontal, the shingles must be installed as required by the manufacturer — steep-slope work goes entirely to the instructions.
What does the code require of the nail itself?
A roofing nail of galvanized steel, stainless steel, aluminum or copper, minimum 12-gage shank, minimum 3/8-inch head, long enough to reach 3/4 inch into the sheathing.
R905.2.5 is the specification most homeowners never see. Fasteners for asphalt shingles must be galvanized steel, stainless steel, aluminum or copper roofing nails, minimum 12-gage [0.105 inch] shank with a minimum 3/8-inch-diameter head, complying with ASTM F1667, “of a length to penetrate through the roofing materials and not less than 3/4 inch (19.1 mm) into the roof sheathing.”
| Requirement | R905.2.5 / R905.2.6 |
|---|---|
| Material | Galvanized steel, stainless steel, aluminum or copper roofing nails |
| Shank | Minimum 12-gage (0.105 inch) |
| Head | Minimum 3/8-inch diameter |
| Standard | ASTM F1667 |
| Penetration | Through the roofing materials and not less than 3/4 inch into the sheathing |
| Count | Manufacturer’s minimum, never fewer than 4 per strip shingle |
Note what the list does not contain. The section names roofing nails and gives no staple option, and it sets a head diameter that a finish or framing fastener does not meet.
On a thin deck the code stops asking for 3/4 inch of penetration and starts asking for the nail to come all the way through. That is a requirement you can see from inside the attic.
What changes on an older house with a thin deck?
The rule flips from a depth to a pass-through: where the sheathing is less than 3/4 inch thick, the fasteners must penetrate through the sheathing.
That is the closing sentence of R905.2.5, and it matters on a great many Central Kentucky houses, because 1/2-inch sheathing and board decking are both thinner than the 3/4-inch figure the first half of the sentence assumes. On those roofs a nail that merely bites is not compliant; it has to come out the other side.
This is also the one fastening requirement a homeowner can check without getting on the roof. From inside the attic on a bright day, the underside of the deck shows the nail points that came through. Rows of points spaced across each course read differently from a scattered few, and a field with almost no points showing on a thin deck is worth a question. It is an observation, not an inspection — but it is physical evidence, and it is free.
R905.2.1 sits behind all of this: asphalt shingles “shall be fastened to solidly sheathed decks.” Spaced decking is not a substrate the section contemplates for shingles at all.
Where wind speed enters the fastening question
Through the shingle’s classification, not through the nail count. The code ties the required shingle class to the design wind speed for the location.
R905.2.4.1 requires asphalt shingles to be tested to ASTM D7158 and to meet the classification in Table R905.2.4.1 for the applicable ultimate design wind speed, with an exception allowing shingles outside D7158’s scope to be tested and labelled to ASTM D3161 instead. In the table, an ultimate design wind speed of 110 or 116 mph calls for class D, G or H; 129 and 142 mph call for G or H; 155 mph and above call for H. The packaging has to carry a label showing the classification.
Which figure applies here is a county-by-county question, and our Kentucky design wind speed and snow load post has the county values. Two other sections usually come up in the same conversation: the edge detail in our drip edge code notes, and what may be reused on a tear-off in our material reinstallation post. If you are not sure which rulebook your project falls under at all, start with which roof code applies.
What I look at on a fastening complaint
General craft, not a verdict on any particular roof. When shingles lift or slide and the roof is not old, fastening is the first thing I want evidence about rather than opinions about, and the evidence has three parts. The wrapper or the manufacturer’s published instructions for that exact product, because that is where the governing count lives. The fastener actually used — material, shank, head — since R905.2.5 is a specification, not a preference. And the deck thickness, because it decides whether the standard is 3/4 inch of penetration or full pass-through, and it is the part nobody writes down. A photograph of the underside of the deck and a photograph of the nail line on a removed shingle answer more than a long conversation does. Where any of that is in dispute, the manufacturer’s instructions and the code section are documents anyone can read; the installer’s recollection is not.
Can a roofer use staples on asphalt shingles in Kentucky?
R905.2.5 specifies roofing nails of galvanized steel, stainless steel, aluminum or copper with a minimum 12-gage shank and 3/8-inch head complying with ASTM F1667. It lists no staple option, and the manufacturer’s instructions may be stricter still.
If the wrapper says six nails and the roofer used four, is that a code violation?
R905.2.6 requires the minimum number of fasteners required by the manufacturer, with four per strip shingle as an absolute floor. Where the manufacturer requires six, six is the requirement the code enforces.
How deep does a roofing nail have to go?
Through the roofing materials and not less than 3/4 inch into the roof sheathing. Where the sheathing is less than 3/4 inch thick, the fastener must penetrate through the sheathing.
Last updated: October 28, 2026
By Central Roof Repair · Call or text (859) 310-1209.
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