Roofing Nail Patterns: 4-Nail vs 6-Nail and FL Requirements (2026)

Every asphalt shingle on your roof is held in place by nails. How many nails are used per shingle, where they are placed, and what type of nails are used all have a dramatic impact on how well your roof performs during high winds. This is not a theoretical concern in Pinellas County, FL. It is a matter of home safety in one of the most hurricane-vulnerable areas in the United States.

The Florida Building Code takes nail patterns seriously, and for good reason. After Hurricane Andrew ripped through South Florida in 1992, investigators found that improper nailing was one of the leading causes of roof failure. Shingles that were installed with too few nails, nails in the wrong position, or nails driven too deep were torn off in the wind, exposing the roof deck and allowing catastrophic water intrusion.

For Pinellas County homeowners, understanding the difference between the standard 4-nail pattern and the high-wind 6-nail pattern is essential knowledge for any roofing project. This guide covers everything you need to know about nail patterns, nail types, and Florida-specific requirements.

Understanding Roofing Nail Patterns

A nail pattern refers to the number and placement of nails used to secure each shingle strip to the roof deck. Asphalt shingle manufacturers specify a nailing zone on each shingle, which is a narrow band across the shingle where nails should be placed. This zone is positioned so that each nail passes through both the shingle being installed and the top edge of the shingle in the course below, creating a double-layered fastening point.

The Standard 4-Nail Pattern

The 4-nail pattern is the baseline installation method for asphalt shingles in most of the country. Four nails are placed evenly along the nailing line of each standard 3-foot shingle strip. The nails are typically positioned:

• One nail approximately 1 inch from each end of the shingle
• Two nails evenly spaced between the end nails (approximately 12 inches apart on a standard 36-inch shingle)
• All nails placed on the manufacturer's designated nailing line, typically 5/8 inch to 1 inch above the cutout or tab slots

The 4-nail pattern is adequate for areas with design wind speeds below 110 mph. However, this does not include Pinellas County, which falls in a higher wind speed design zone.

The High-Wind 6-Nail Pattern

The 6-nail pattern adds two additional nails to each shingle strip, bringing the total to six. The additional nails are placed between the existing four nails, reducing the spacing to approximately 6 to 7 inches between nails on a standard 36-inch shingle.

The extra nails make a significant difference in wind resistance:

• Up to 40% greater wind uplift resistance compared to the 4-nail pattern
• Better load distribution across the shingle surface
• Reduced stress on individual nail points during wind events
• Compliance with manufacturer's high-wind installation requirements, which is necessary to maintain the full wind speed warranty

Florida's Nail Pattern Requirements: Why 6-Nail Is Mandatory

Florida is divided into wind speed zones based on the risk of hurricane-force winds. The Florida Building Code assigns design wind speeds to every location in the state, and these wind speeds determine the minimum construction standards for roofing.

Pinellas County falls within the Wind-Borne Debris Region (WBDR) of the Florida Building Code, with design wind speeds ranging from approximately 130 to 150 mph depending on the specific location within the county. This classification triggers the requirement for the 6-nail pattern on all asphalt shingle installations.

The Code Requirement

The Florida Building Code (FBC) requires that asphalt shingles installed in areas with design wind speeds of 110 mph or greater must use the manufacturer's high-wind installation instructions. For virtually every shingle manufacturer, this means a minimum of 6 nails per standard shingle strip.

Since all of Pinellas County exceeds the 110 mph threshold, the 6-nail pattern is required for every asphalt shingle roof installation in the county, whether the home is in downtown St. Petersburg, Gulf-front Clearwater Beach, or inland Palm Harbor.

Enhanced Wind Zones Within Pinellas County

While all of Pinellas County requires the 6-nail pattern, some areas face even higher wind speed requirements. Properties within one mile of the coast or near large bodies of open water may fall into higher exposure categories that require additional measures beyond the 6-nail pattern, such as:

• Enhanced underlayment requirements (full peel-and-stick)
• More stringent starter strip specifications
• Higher-rated shingle products (130+ mph wind rating)
• Additional roof deck attachment requirements

Consequences of Non-Compliance

Using a 4-nail pattern in Pinellas County is a code violation that can have serious consequences:

• Failed inspection: The building inspector will not pass a roof installed with a 4-nail pattern, requiring the contractor to remove and reinstall the shingles correctly
• Voided manufacturer warranty: Shingle manufacturers will not honor wind damage claims if their high-wind installation instructions were not followed
• Insurance complications: Your homeowner's insurance may deny wind damage claims if the roof was not installed to code
• Reduced wind resistance: A 4-nail pattern in our wind zone provides significantly less protection during a hurricane
• Liability for the contractor: A licensed roofer who installs a 4-nail pattern in a 6-nail zone faces disciplinary action from the state licensing board

Nail Types for Roofing: Ring-Shank vs Smooth-Shank

The type of nail used is just as important as the pattern. Not all roofing nails are created equal, and the Florida Building Code has specific requirements for nail characteristics.

Smooth-Shank Nails

Smooth-shank nails have a straight, smooth shaft. They are the most basic type of roofing nail and were the standard for decades. Smooth-shank nails are easy to drive and relatively inexpensive.

However, smooth-shank nails have a significant weakness: they can back out over time. As the roof deck expands and contracts with temperature changes, smooth nails can gradually work their way up. This is called "nail pop" and is a common issue in Pinellas County, where roof temperatures can swing from 70 degrees to over 150 degrees in a single day.

Ring-Shank Nails

Ring-shank nails have a series of concentric rings along the shaft. These rings act like tiny barbs that grip the wood fibers of the roof deck, creating significantly more withdrawal resistance than smooth-shank nails.

Ring-shank nails provide:

• Up to 40% more withdrawal resistance than smooth-shank nails of the same size
• Better resistance to nail pops caused by thermal cycling
• Superior holding power in wind events
• Compliance with Florida Building Code high-wind requirements

Corrosion Resistance in Pinellas County

Pinellas County is surrounded by salt water. The Gulf of Mexico to the west and Tampa Bay to the east create a salt-air environment that accelerates metal corrosion. Standard uncoated nails can begin rusting within months of installation, weakening their holding power over time.

The Florida Building Code requires corrosion-resistant nails for all roofing applications. The two most common options are:

• Hot-dipped galvanized: Steel nails coated with a thick layer of zinc. This is the minimum standard for most Pinellas County installations and provides good corrosion resistance for homes more than a mile from the coast
• Stainless steel: The premium option that provides the best corrosion resistance. Recommended for coastal Pinellas County properties (Clearwater Beach, Indian Rocks Beach, Treasure Island, St. Pete Beach, and other waterfront areas) where salt exposure is highest

Electro-galvanized nails (a thinner zinc coating applied electrically) are not recommended for Pinellas County roofing. The coating is too thin to withstand our salt-air environment and will corrode much faster than hot-dipped galvanized or stainless steel nails.

Nail Length Requirements

Using the correct nail length is critical for proper roof performance. A nail that is too short will not grip the deck adequately, while a nail that is too long can penetrate through the deck and create a hazard or moisture path in the attic.

The Florida Building Code and shingle manufacturer instructions require that roofing nails penetrate at least 3/4 inch into the roof deck, or completely through the deck if the sheathing is less than 3/4 inch thick.

Note: Re-roofing over an existing layer of shingles (overlay) is becoming less common in Pinellas County because most jurisdictions now require a complete tear-off to the deck for proper inspection and code compliance. However, where overlay is permitted, longer nails are essential to achieve proper deck penetration through both layers of shingles.

Overdriven vs Underdriven Nails: The Quality Control Challenge

Even with the correct nail type, length, and pattern, the way each nail is driven into the shingle determines whether it does its job. Two of the most common installation defects in Pinellas County roofing are overdriving and underdriving nails.

Overdriven Nails

An overdriven nail is one that has been hammered too deep into the shingle. When a nail is overdriven, the nail head breaks through the shingle's fiberglass mat layer and sits below the surface of the shingle. This causes several problems:

• Reduced holding power: The nail head no longer grips the full thickness of the shingle material. Instead of clamping the shingle to the deck, the nail has torn through and is holding only a thin remnant of material
• Water infiltration point: The hole created by the overdriven nail becomes a potential entry point for water, especially during wind-driven rain
• Manufacturer warranty void: Every major shingle manufacturer specifies that nails must be driven flush with the shingle surface. Overdriven nails can void the wind damage warranty
• Inspection failure: Pinellas County building inspectors check for overdriven nails, and a roof with widespread overdriving will not pass inspection

Underdriven Nails

An underdriven nail is one that has not been driven deep enough, leaving the nail head sitting above the shingle surface. Underdriven nails create a different set of problems:

• Shingle sealing failure: The raised nail head creates a bump that prevents the shingle above from lying flat and sealing properly. The adhesive strip on asphalt shingles needs full contact with the shingle below to create a wind-resistant bond
• Visible bumps: Underdriven nails create visible bumps on the roof surface that detract from appearance and indicate poor workmanship
• Increased wind vulnerability: Without a proper seal between shingle courses, wind can get under the shingle edges and lift them, leading to progressive failure during storms
• Nail back-out risk: An underdriven nail is already partially out of the deck and more likely to continue backing out over time

The Correct Nail Depth

A properly driven roofing nail sits flush with the shingle surface. The nail head should be fully seated against the shingle without breaking through the mat. When you run your hand over a properly nailed shingle, you should feel the slight profile of the nail head but it should not protrude above the surface or sit in a depression below the surface.

Hand-Nailing vs Pneumatic Nailing

The debate between hand-nailing and pneumatic (air gun) nailing has been going on in the roofing industry for decades. Both methods are code-compliant in Pinellas County when done correctly, but they have different strengths and weaknesses.

Pneumatic Nailing: The Industry Standard

The vast majority of roofing crews in Pinellas County use pneumatic nail guns (also called coil nailers or roofing guns). When properly set up and maintained, pneumatic nailers produce consistent, high-quality nail drives at a fraction of the time required for hand-nailing.

The key to quality pneumatic nailing is pressure adjustment. The air compressor pressure must be adjusted based on:

• The temperature (hot shingles are softer and easier to overdrive)
• The deck material and condition (newer, firmer decking requires more pressure than older, softer wood)
• The slope of the roof (the angle of the gun changes on steeper pitches)
• The specific nail being used (different nail weights require different pressures)

A good roofing crew adjusts pressure settings throughout the day as conditions change and checks their work regularly to catch any overdriven or underdriven nails.

Hand-Nailing: The Premium Option

Some Pinellas County roofing contractors offer hand-nailing as a premium upgrade. Hand-nailing gives the installer direct tactile feedback on every nail, making it easier to achieve perfect depth consistently. However, it takes roughly twice as long as pneumatic nailing, which increases labor costs.

Hand-nailing is particularly valuable in these situations:

• Older homes with variable deck conditions (some sections softer than others)
• Premium shingle installations where maximum warranty coverage is desired
• Small or complex roof sections where a nail gun is difficult to maneuver
• Cold-weather installations where shingles are stiffer and more prone to cracking (less relevant in Pinellas County)

How Nail Patterns Affect Insurance and Wind Mitigation

In Pinellas County, your roof's nail pattern directly affects your homeowner's insurance premium through the Florida wind mitigation inspection. When a wind mitigation inspector evaluates your roof, one of the key items they check is the nail pattern.

A verified 6-nail pattern can qualify your home for insurance discounts because it demonstrates enhanced wind resistance. The wind mitigation form (OIR-B1-1802) specifically asks about the number of nails per shingle, and the answer is categorized as either:

• Standard (4 nails or fewer): Does not qualify for the enhanced nailing discount
• Enhanced (6 nails or more): Qualifies for insurance credits that can reduce your wind premium

For Pinellas County homeowners, the insurance savings from a verified 6-nail pattern can be substantial. Combined with other wind mitigation features (hip roof shape, secondary water barrier, hurricane straps), the total premium reduction can be hundreds of dollars per year.

Roof Deck Nailing: A Related But Separate Requirement

While this guide focuses on shingle nail patterns, it is worth noting that the roof deck sheathing itself also has specific nailing requirements in Pinellas County. The Florida Building Code requires roof deck panels to be nailed with 8d ring-shank nails at:

• 6 inches on center along all panel edges (where the panel meets a truss or rafter)
• 12 inches on center in the field (the interior area of the panel between edges)

This deck nailing schedule is often referred to as the "6/12 pattern" and is more stringent than the 6/12 or 8/12 patterns used in lower-wind areas. During a re-roof, your Pinellas County contractor should inspect the existing deck nailing and add nails as needed to meet current code.

For more details about roof deck requirements, see our guide on roof deck replacement costs in Pinellas County.

Common Nail Pattern Mistakes in Pinellas County

Even experienced roofing crews can make nail pattern errors. Here are the most common mistakes Pinellas County building inspectors encounter:

• High nailing: Placing nails above the manufacturer's designated nailing line. This leaves the bottom portion of the shingle unsecured and dramatically reduces wind resistance
• Low nailing: Placing nails below the nailing line, through the exposed portion of the shingle. This creates visible nail heads and potential leak points
• Inconsistent spacing: Using 6 nails but spacing them unevenly, which creates weak points where the gap between nails is too large
• Missing the overlap: Failing to nail through both the shingle being installed and the top edge of the shingle below. This means only one layer of shingle is holding the nail
• Crooked nails: Driving nails at an angle rather than straight. Angled nails do not seat properly and have reduced holding power
• Wrong nail type: Using smooth-shank or non-corrosion-resistant nails in a zone that requires ring-shank galvanized or stainless steel

What to Ask Your Pinellas County Roofer About Nail Patterns

Before hiring a roofing contractor, ask these questions about their nailing practices:

• "Do you use a 6-nail pattern for all shingle installations in Pinellas County?"
• "What type of nails do you use? Are they ring-shank and corrosion-resistant?"
• "How do you manage your air compressor settings to prevent overdriving?"
• "Do you check nail depth throughout the installation?"
• "What nail length do you use for the specific shingles being installed?"
• "Will you re-nail the roof deck to meet current code requirements?"
• "Do you offer hand-nailing as an option?"

A professional roofing contractor should answer these questions without hesitation. If they seem unsure about nail pattern requirements or cannot explain their quality control process, consider other options. To understand how these requirements affect overall pricing, see our guide on how roofers charge for their work.

Frequently Asked Questions

What is the difference between a 4-nail and 6-nail roofing pattern?

A 4-nail pattern uses four nails per shingle strip, placed along the nailing line above the exposure area. A 6-nail pattern adds two additional nails for a total of six per strip, providing significantly greater wind resistance. The 6-nail pattern is required in Florida's high-wind zones, including all of Pinellas County, and provides up to 40% more wind uplift resistance than the 4-nail pattern.

Does Pinellas County require 6-nail pattern roofing?

Yes. Pinellas County falls within Florida's Wind-Borne Debris Region and enhanced wind zone, which requires a 6-nail pattern for asphalt shingle installation. This requirement applies to all new construction and re-roofing projects. The 6-nail pattern is mandated by the Florida Building Code to meet the county's wind speed design requirements.

What type of nails are required for roofing in Florida?

The Florida Building Code requires corrosion-resistant roofing nails for all installations. Ring-shank nails are strongly recommended and often required in high-wind zones like Pinellas County because they provide superior holding power compared to smooth-shank nails. Nails must be at least 12-gauge with a minimum 3/8-inch head diameter. Stainless steel or hot-dipped galvanized nails are required to resist Florida's humid, salt-air environment.

How long should roofing nails be?

Roofing nails must be long enough to penetrate at least 3/4 inch into the roof deck (or through the deck if the sheathing is less than 3/4 inch thick). For standard asphalt shingles on 7/16-inch or 1/2-inch decking, this typically means using 1-1/4 inch nails. For architectural (dimensional) shingles, which are thicker, 1-1/2 inch or 1-3/4 inch nails may be needed to achieve proper penetration.

What happens if roofing nails are overdriven or underdriven?

Overdriven nails (hammered too deep) cut through the shingle mat, reducing holding power and potentially voiding the manufacturer's warranty. Underdriven nails (not driven flush) sit proud above the shingle surface and create bumps that prevent the next course of shingles from sealing properly. Both conditions compromise wind resistance and are common reasons for inspection failures in Pinellas County.

Is hand-nailing better than pneumatic nailing for roofing?

Both methods can produce quality results when done correctly. Hand-nailing gives the roofer more control over nail depth and placement but is significantly slower. Pneumatic (air gun) nailing is faster but requires careful pressure adjustment to avoid overdriving or underdriving nails. In Pinellas County, most professional crews use pneumatic nailers with proper pressure settings and regular quality checks throughout the installation.

Final Thoughts

The nail pattern on your Pinellas County roof is not a minor detail. It is a critical safety feature that determines how well your home withstands hurricane-force winds. The 6-nail pattern required by the Florida Building Code exists because decades of hurricane experience have proven that more nails save more roofs.

When planning your next roofing project, make sure your contractor uses the proper 6-nail pattern with ring-shank, corrosion-resistant nails of the correct length. Verify their quality control process for preventing overdriven and underdriven nails, and do not hesitate to ask about their specific nailing practices.

The cost difference between a 4-nail and 6-nail pattern is minimal, typically just $5 to $15 per roofing square in additional nails and labor. But the difference in wind resistance is enormous. In Pinellas County, where the next hurricane is always a question of when and not if, those extra two nails per shingle are among the best investments you can make in your home's protection.