Shopping for roofing nails is the least worry for many professional roofers. This is understandable after installing, replacing, and repairing dozens of roofs.
Unfortunately, it’s among the most confusing subjects for DIY enthusiasts. So we’ve prepared this guide to help you understand standard roofing nail lengths and how to choose the right nail lengths depending on your project needs.
Roofing Nail Length
One-inch nails are the standard length for architectural shingles with 3/8-inch thick sheathing. However, consider 1 1/4-inch nails if your building codes require thicker sheathing. Similarly, consider longer nails if using thicker shingles. Otherwise, the nails may not fully penetrate the sheathing.
Why Roofing Nail Length Matters
Roofing nails come in standard sizes for one main reason – attachment strength. The nails must fully penetrate the roofing sheets/shingles and go into the decking to a specific depth for maximum roof strength. Otherwise, you get a weak roof easily blown by winds and storms.
At the same time, excessively long roofing nails can poke through the decking and penetrate the attic ceiling (where present), causing new concerns.
For instance, some homeowners consider the attic space a half-story used for overhead storage. In such instances, sharp nail tips protruding from the attic ceiling are a safety hazard. Moreover, protruding nails can cause leaks in the attic.
Factors to Consider when Choosing the Right Roofing Nail Length
Choosing the correct length of roofing nails comes down to five main factors – nail type, shingle properties, sheathing properties, decking type, and whether the roof includes additional layers that impact the thickness.
Type of Roofing Materials
How many types of roofing materials can you count? It’s a long list, from asbestos cement (AC) sheets to aluminum sheets, polycarbonate roofing sheets, and asphalt shingles.
However, most Americans use asphalt, wooden, metal, and slate shingles. Clay and cement tiles are common, though they don’t require nailing.
Unfortunately, it escapes most people’s minds that all these roofing materials have different thicknesses.
For instance, a standard three-tab asphalt shingle is 3/16 inches thick. Meanwhile, metal roofing sheets are thinner. For instance, gauge 26 carbon steel sheets (the industry standard for residential applications) are 0.0179 (3/160) inches thick.
That’s about 10x thinner than standard asphalt shingles. On the other hand, wooden shingles are 3/8 to 5/8 inches thick.
So, you can do with shorter nails for metal roofs but require longer nails for roofing shingles, especially wood shingles.
Shingle Thickness
Fortunately, asphalt shingles are the standard roofing material in the US, making nail shopping less stressful. But, again, the various asphalt shingle types vary in thickness.
For instance, the standard thickness of three-tab shingles is 3/16 inches. Meanwhile, architectural shingles are 50% thicker (and heavier). This means a regular architectural shingle is 9/32 inches (compared to 6/32 inches for three-tab shingles).
Finally, impact-resistant shingles can be up to 1/4 inches thick, with some thicker. For instance, Class-4 impact-resistant shingles are thicker to resist greater impact.
You need longer nails for thicker shingles to fully penetrate the shingle and attain a sufficient depth in the sheathing.
Roof Deck Type and Thickness
Let’s come to roof deckings (also known as sheathings). Again, two factors are critical, the decking type (material) and thickness.
Oriented Strand Board (OSB) is the most popular sheathing material, accounting for more than 50% of all sheathing installations in the country since 2007. It’s lightweight and durable.
Moreover, it’s cheaper than the other options. Plywood is another popular choice as it’s dense, strong, and water-resistant.
You may also come across wood-board and concrete sheathings. However, these two are less popular.
The various materials have different thicknesses and thus require different nail lengths for a strong roof. For instance, OSB sheathings range from 5/16 inches to 3/4-inch thick boards. Meanwhile, most plywood sheathings are 3/8 inches to 1/2 inches thick.
The thicker sheathings accommodate longer nails for a stronger roof. However, you need shorter nails for thinner sheathings to avoid penetrating the other side of the decking material.
Additional Layers Add Thickness
Finally, you should consider additional roofing materials that may impact the overall roof thickness. Two excellent examples are roof overlays, and shingle/panel overlaps.
A roof overlay is when you install a new roof over the old one. So, unlike regular reroofing projects where the old roof is first uninstalled, overlays keep the old roof.
Right away, you realize that the total roof thickness is greater. Therefore, you need longer nails to reach the roof decking.
In this case, the total shingle thickness is the sum of the thicknesses of the old and new shingles.
Similarly, overlapping sections of the roof comprise two roofing sheets/shingles on top of each other. Therefore, you must consider the additional thickness.
For instance, overlapping architectural shingles form 2*(9/32) = 9/16-inch thick shingle layers. You need longer nails to hold down the extra-thick layer strongly.
What Size Nails should I Use for Roofing?
The best idea is to work with a roofing contractor or qualified professional. They understand roofing nail sizes like the back of their hands.
Alternatively, use roofing nail calculators found on reputable websites. Most calculators use industry figures generated from various building codes with input from experienced professionals.
However, perhaps you cannot find either. In that case, consider the following general guidelines.
Correct Nail Length for Roof Sheathing
Roofing Nail Length for 1/2-Inch Thick Plywood
We recommend 3/4-inch roofing nails when using a 1/2-inch thick plywood sheathing, assuming you’re using regular asphalt shingles. This is because the nails will penetrate the plywood to a sufficient depth to guarantee a strong hold. However, 1 1/4-inch nail are better if using thicker shingles.
Roofing Nail Length for 5/8-Inch Plywood
Use 1-inch roofing nails on 5/8-inch plywood sheathing when using three-tab composite shingles. Meanwhile, consider 1 1/4-inch roofing nails for the same plywood thickness when using dimensional composite shingles or 3-tab shingles over three-tab shingles.
On the same note, find 1 1/2-inch roofing nails for nailing dimensional shingles over three-tab shingles.
Roof Nail Length for 3/4-Inch Plywood
For 3/4-inch thick plywood sheathing, use 1 1/2-inch to 2-inch nails. Nails shorter than 1 1/2 inches may not penetrate the plywood sheathing to the desired depth. Thus, you may be left with a weak roof. If you’re unsure, err on the side of longer nails.
Roof Nail Length for 1/2-Inch OSB
The ideal nailing length for 1/2-inch OSB is 3/4 inches. Three-quarter-inch nails provide a secure hold without penetrating through the sheathing. Of course, you must choose the right shank type and thickness for maximum roof strength.
Roofing Nail Length for 7/16-Inch OSB
We use 1 1/2-inch to 2-inch nails for 7/16-inch thick OSB sheathing. Remember that 7/16 of an inch is about half an inch. So, you want longer than standard nails to get through the shingles and reach a good depth in the sheathing. Unfortunately, one-inch nails don’t offer enough holding strength.
Can Roofing Nails be too Long?
Yes, roofing nails can be too long for the project. Ideally, the nails should only be long enough to penetrate the shingles and 3/4 of the sheathing. Otherwise, longer nails may penetrate the other side of the sheathing, causing damage and safety hazards.
Consequences of Wrong Roof Nail Length
Too short or too long roofing nails pose various problems. For instance, extremely short nails don’t hold the roof strongly, increasing the risk of shingles being blown away by light storms and winds.
Moreover, you may be tempted to overdrive the nails. Meanwhile, long nails can damage the sheathing, compromising the roof’s structural integrity.
Types of Roof Nails
Besides length, you should consider roofing nail materials, shank type and size, and head diameter and type.
Regarding material, your options include aluminum nails, galvanized steel nails, stainless steel roofing nails, and copper nails. However, galvanized roofing nails (with a zinc coating) are the most common, though copper roofing nails are more durable.
Meanwhile, the two most common shank types are ring and smooth. Ring shank nails are the standard choice for roofing projects as they provide a stronger hold and resist winds better. Meanwhile, smooth shank nails work best for basic projects.
Additional Roof Nailing Tips
The following are additional nailing tips to ensure a strong, durable, and hazard-free asphalt roof;
- Follow the roofing manufacturer’s instructions
- Ensure proper roofing nail length
- Ensure proper shingle layer alignment
- Don’t under or overdrive nails
- Avoid nailing cracked decking
- Use the right nailing tools (e.g., nail guns)
Roofing Nail Length FAQs
What Size Roofing Nails for Architectural Shingles?
The International Building Code requires a 12-gauge shank and 3/8-inch diameter head nails for architectural shingles. Meanwhile, the minimum nail length requirement is one-inch. However, consider a 1 1/4-inch nail for thicker shingles. Also, consider longer nails for thicker sheathing materials.
Can I Use Screws for Roofing Shingles?
No, you must not use screws for roofing shingles, as screws leave small gaps around the fastener that may cause leaks. Instead, use roofing nails. Specifically, consider 10-12 gauge zinc-coated steel or aluminum nails with barbed or deformed shanks. We recommend nailing by hand or using a coil nailer.
What Type of Nails Should I Use for Shingles?
Ring roofing nails made from hot-dipped galvanized steel are the best for roofing shingles. They hold down roofing felt and asphalt shingles exceptionally well. Ideally, you want 12 gauge or thicker nails. Meanwhile, the ideal roofing nail lengths depend on the thickness of the sheathing and shingles.
How Many Nails Per Square?
Most roofing manufacturers recommend four nails per shingle in the middle of the roof and five on the first row for standard roofing applications. This works out to 320 nails for every square (100 square feet).
Are 7/8 Roofing Nails Long Enough?
No. Unfortunately, 7/8-inch nails are not long enough for regular roofing applications. For instance, it won’t fully penetrate a 1/2-inch OSB sheathing. Yet most projects require sheathings up to 5/8 inches thick. So instead, consider 1 1/4 to 2-inch long nails.
What’s the Correct Cedar Shake Roofing Nail Length?
Generally, the nails must be long enough to fully penetrate the shingles and go 1/2 to 3/4 inches into the cedar shingle sheathing. So you need a 1 1/2-inch nail for regular cedar shake roofing projects. Use ring shank nails with a blunt tip to prevent cracking.
Summary
One-inch nails are the industry standard for regular roofing projects, especially when using three-tab asphalt shingles over a 3/8-inch thick OSB sheathing.
However, consider longer nails for thicker shingles or sheathing and shorter nails for thinner roofing materials.