Nail size is more important than you might think when sheathing a roof. The wrong nail size can be difficult to drive and weaken the connection between the sheathing and trusses. The best roofing nails for 7/16 sheathing are 3/8-inch to 7/16-inch diameter. These are called 8d common nails or 8-penny nails.
Good roofing requires quality roofing sheets, reliable roof framing, and a proven technique. Of course, it also requires an experienced or highly skilled roofer.
However, the list doesn’t end there. If you want the perfect roof, you must also select the right roofing nail length. Otherwise, you may damage the roofing sheets and underlayment material. The wrong nails can also result in weak roof framing, increasing the risk of the roof being blown off by the wind.
What’s the Best Nail Size for Roof Sheathing?
Generally, you need one-inch nails for ⅜-inch thick roof sheathing. However, some building codes require thicker sheathing, so you can use 1 ¼-inch long nails for the sheathing project. Longer nails are necessary for roofing projects involving thicker sheathing material to penetrate the OSB material underneath fully.
Can I Use Screws for Roof Sheathing?
Before discussing nail selection, many roofers often wonder whether you can use screws for roof sheathing. Is it a good alternative to nails?
The short answer is -yes. Although most roofers prefer nails, screws are almost as effective and more practical in certain projects.
For instance, screws make more sense for small projects because they offer more control when inserting and extracting. Screws also offer more tensile strength. Tensile strength refers to a material’s ability to resist breaking under pressure.
For instance, you need fasteners with high tensile strength when joining pieces that typically bear weight or come under significant tension once installed.
So, screws make sense in sheathing since the sheathing material bears significant weight once the roofing sheets are installed.
Nails or Screws for Roof Sheathing?
Nails are the better choice if you have to pick between nails vs. screws for sheathing. Screws are very good too. However, nailing down your sheathing materials instead of screwing them has several critical advantages.
- Nails are easier to “nail”: You want to move as quickly as possible when installing sheathing material. Unfortunately, screwing screws won’t let you move fast enough. Nails, on the other hand, are easy to insert with a hammer or nail gun.
- Nails are more flexible: Think about it; how often do you see bent screws? It’s not as common as bent nails because nails are more flexible under pressure. Screws will snap rather than bend.
- Nails offer excellent grip: Screws offer very good gripping, too. However, few fasteners come close to shank nails if you want the best grip in wooden structures. And it’s understandable because, unlike traditional nails with smooth shafts, shank nails have ringed shafts – like screws. The shanks increase gripping power by up to 40%.
Overview of Roof Sheathing, Thickness, and Nail Patterns
Once you’ve settled on nails for your roof sheathing project, the next thing you need to assess is your sheathing material. The type of sheathing, its thickness, and other qualities directly affect the type and size of nails ideal for the sheathing project.
Roof sheathing or decking refers to the pieces of wooden boards placed on the trusses and wood joists. They are typically 4×8 boards and are installed perpendicularly on the roof frame.
The main purpose of the sheathing material is to ensure a straight roof. Roof sheathing also helps distribute the weight of the roof.
Roof sheathing is made from oriented strand board (OSB) or plywood, though most roofers prefer OSB because it’s lightweight and cheaper. Wood board is another common material.
Roof Sheathing Thickness
Roof sheathing comes in two main sizes ¾-inch and ⅜-inch thickness. The choice of thickness depends on the project type. However, many experts recommend thicker sheathing as it supports more weight.
Thicker sheathing material also guarantees a stronger decking and reduces the risk of roof sagging.
Sheathing Nailing Patterns
Roof sheathing nailing patterns also vary depending on the project type. For instance, if you live in a location with frequent earthquakes, you need more nails per square meter. The same applies in areas where you need to protect the roof from strong winds.
Another important factor is your local building codes. Each municipality has different requirements. So, it’s best to visit your local building authority before deciding.
However, generally, you need to space the nails every six inches on center at supported panel ends and edges and every 12 inches at intermediate supports.
Roof Sheathing Nails Sizing: Gauge, Length, and Diameter
So, now you’ve selected a sheathing material and are ready to choose nails for the sheathing installation. The following tips and considerations will come in handy.
Nail Materials
Roof sheathing nails (and nails for other roofing projects) are typical;y made from four materials as follows;
Aluminum
Aluminum nails are very common because they are the most affordable for roofing projects. They are also incredibly lightweight. Above all, aluminum nails are highly rust-resistant, thus fairly durable.
The only downside is that aluminum nails readily react with acids. This makes them ill-suited for coastal projects. Aluminum also rusts fast when exposed to moisture for prolonged periods.
Stainless Steel
Stainless steel nails are even more durable than aluminum. They are also very long-lasting. More importantly, they are as corrosion-resistant as aluminum nails but come in almost the same price range. So, they’re a good choice if you’re looking for quality sheathing nails at a good cost.
The only real challenge with stainless steel nails is carbon footprint. Stainless steel, though recyclable, is very difficult to make. Stainless steel nails are also heavy.
Galvanized Steel
Some people consider galvanized nails the best choice for roof sheathing, and they’re not too wrong, given the benefits of galvanized steel.
Though they are also made from stainless steel, galvanized nails are coated in zinc, making them highly rust-resistant. The zinc coating also adds durability.
Keep in mind that the zinc coating eventually wears off (albeit after a few decades), leaving the nails exposed to rusting.
Copper
Finally, copper nails are arguably even better than galvanized nails for any roofing project, including roof sheathing installation. The main reason is that copper is stronger than all the above options, including galvanized steel nails.
The nails can last 100+ years after installation. It’s also easier to remove copper nails without damaging the roofing material.
Unfortunately, copper nails are the most expensive of the four options. As a result, they are only used in special projects, such as slate roofs that typically last more than a decade.
Types of Nails
Besides material, it also helps to consider the shape of the nail. Roof sheathing nails come in three main types;
Smooth Shank Nails
Smooth shank nails are the simplest and most common nail type. They are also the easiest to make and cheapest to buy. They are completely smooth and free of grooves.
This quality makes them easy to drive with a hammer, making them an excellent choice for framing and finishing projects.
Unfortunately, the same quality makes them ill-suited for roofing projects because they don’t offer enough withdrawal resistance.
Ring Shank Nails
Ring shank nails have a series of circular threads/rings throughout the nail’s shank. As such, they offer better drip than smooth shank nails. Indeed, research shows they offer twice the withdrawal resistance of smooth shank nails.
However, the main downside is that ring-shank nails can damage solid hardwood when withdrawing the nail. Fortunately, no one uses solid hardwood for roof sheathing.
Screw Shank Nails
Finally, screw shank nails are designed with spiral threads, similar to screws, to ensure superb fastening for maximum hold.
They offer the highest level of withdrawal resistance of the three nail types and are characterized by a diamond tip that makes it easy to penetrate the material.
Unfortunately, screw shank nails are more expensive than smooth and ring shank alternatives. They are also difficult to drive into dense woods. That said, though, they are considered the best option for sheathing and other roof decking projects.
Nail Sizes
Finally, roof sheathing nails come in different sizes. It’s critical to find the right nail size to ensure a quality project. The three most important factors are nail gauge, nail length, and nail diameter (shank and head).
Remember that nail “gauge” is another word for nail thickness. One gauge is the number of nails in one inch when the nails are lined up side by side. So, the term “gauge” is often used when describing the diameter of nails.
Anyway, here’s how to choose nail diameter and length.
- Nail Diameter: When evaluating nail diameter, you should consider both the shank diameter and head diameter.
- Shank diameter: According to the 2018 Edition of the Internal Building Code (IBC), you should use 12-gauge shank nails for sheathing installation. This is equivalent to 2.67mm. You can also use 13-gauge nails. However, avoid nails smaller than 12 gauges thick.
- Head diameter: The ideal head diameter for roof sheathing installation is 16-gauge. Again, you can use thicker nails but not smaller nails.
- Nail length: Regarding roof nail length, you need 1-inch nails for standard ⅜-inch sheathing material and 1¼-inch nails for ¾-inch sheathing material.
If you’ve read or heard about 16D, 10D, and 8D nails and wonder where roof sheathing nails fall, you should shop for 8D common nails (not sinkers).
The difference between common and sinker nails is that common nails are smooth, while sinker nails have textured heads and coated shanks.
8D nails are around 0.134-gauge and typically 2 ½ inches, whereas the others are much larger. 16D nails, for instance, are 0.148-gauge and 3 ¼ inches long (sinker) and 0.162-gauge and 3 ½-inches (common).
Meanwhile, 10D nails are 0.148-gauge thick and 3-inch long. This makes 16D and 10D nails ill-suited to roof sheathing installation projects.
Tips for Proper Roof Sheathing Installation
After choosing the right nails (material, type, and size), the next step is to install the roof sheathing correctly to ensure a reliable and durable roof. We recommend focusing on five things;
- Check the level of the nailing surface: You want to ensure a level nailing surface. So, shim the trusses or rafters accordingly and install a bocking in bowed or warped surfaces to make the surface flat.
- Ensure proper roof ventilation line with your local codes: A minimum net ventilation of 960 square feet for every 1,000 square feet of the ceiling area is acceptable in most states. However, you can reduce it to 480. Check with your building authority.
- Fasten roof sheathing panels properly: Use 8D nails spaced six inches apart on the center at supported panel ends and edges and 12 inches apart at intermediate supports.
- Cover the sheathing with underlayment felt: A single underlayment felt over the sheathing material minimizes exposure to weather.
- Install the roof according to manufacturer recommendations: A quick call to the manufacturer can help you avoid common blunders during installation.
What Size Nails for Roof Sheathing FAQs
Should roofing nails go through the sheathing?
Yes, the sharp tip of the nail should go through and extend at least ⅜ inches beneath the sheathing material.
What size roofing nails for 7/16 sheathing?
The best roofing nails for 7/16 sheathing are 3/8-inch to 7/16-inch diameter. They are called 8d common nails or 8-penny nails and can be round-headed, sharp-pointed 11-gauge galvanized steel or the equivalent corrosion-resistant roofing nails.
What size nails for OSB sheathing?
8D nails are considered standard for OSB roof sheathing materials. Feel free to use a nail gun or hammer.
What is the best roofing nail length for 1/2-inch plywood?
Ideally, you want to use 1-inch long roofing nails.
What’s the best roofing nail length for 5/8 plywood?
Generally, the nail should go in at least 19mm. This means you should consider 30mm to 35 mm nails.
How many nails do you need per sheet of plywood on the roof?
A truss spacing of 16 inches means you have six trusses per sheathing board. So, you need 6×6 = 36 nails per plywood sheet.
Summary
The type and size of nails you need for a roof sheathing installation project depends on the project itself. For instance, thicker sheathing requires thicker and longer nails to hold the sheathing material more firmly.
You also need different nails types depending on whether you’re using OSB, plywood, or wood board. However, generally, you need one-inch long nails for standard ⅜-inch thick roof sheathing and 1¼ -inch long nails for ¾-inch sheathing material.