Friday, May 26th, 2017 by Joe Boettcher
Did you know one little nail can make or break the stability of your roof? It's true! Any contractor worth his salt knows that great shingle installation hinges on the proper size, number, and placement of nails. Inadequate use of nails during installation can lead to shingles cracking or blowing away and damaging your roof. With this in mind, here are some facts about roofing nails you should be aware of the next time you have roof work done on your home:
You may be tempted to think it doesn't matter what size nail is used during shingle installation as long as it fastens the shingle to the roof, but you should avoid this thinking at all costs! Good roofing is in the details--from the big things like the placement of flashing and ice and water shield, all the way down to the proper size of the smallest nail. To emphasize this fact, the Asphalt Roofing Manufacturer's Association (ARMA) lists some nail size guidelines on their website. According to them, for a nail to be right for shingle installation, it must have a head diameter of at least 3/8" and a nominal shank diameter of 12 gauge. The length of the nail is also crucial because it must be long enough to penetrate the roof decking by at least 3/4", which means your contractor should always consider the type of roofing job when determining what size nail to use. For example, a longer nail will probably be more necessary for a layover than for a tear off because it will have to penetrate more layers of shingles. Your contractor should also be aware of how thick your roof decking is because if it's thinner than 3/4", then the nail will have to be long enough to extend at least 1/8" beyond the deck. All of these factors should always be taken into account when choosing the right size nail for a roofing job.
Typically building codes and shingle manufacturers alike will require four nails to be installed on low-pitched roofs and six on steeper roofs. Six nails are also better for areas with high winds. We at My-Pros like to use six nails because it tends to make for a more stable and sturdier roofing system. However, if a shingle manufacturer should strictly specify four nails for their warranty to be maintained, then your contractor should use four nails to keep the warranty in tact. Obviously, the best option is always the option that gives you the most long-term security both regarding money and the overall quality of your roof.
Nail placement requirements will usually vary by manufacturer, but there are some good general guidelines. First and foremost, nails should never be driven into the shingle so that they're too shallow, too deep, or crooked. A nail is too shallow if it does not penetrate at least 3/4" deep into the roofing deck. A dead giveaway that a nail is too shallow will be if you can see some of the shaft sticking out above the shingle. These nails should be pounded in the rest of the way immediately. Conversely, a nail is too deep when its head penetrates the shingle, which is a problem because it can create a hole or crack in the shingle that could become susceptible to leaks. If you notice your contractor over-driving nails into your roof, you should request that those overdriven shingles be uninstalled, patched with asphalt, and reinstalled immediately (just make sure your contractor knows not to put nails in the spots where the old holes were patched, as this can create unstable shingles). One of the main culprits of overdriven or underdriven shingles is the use of an inadequately adjusted nail gun. Although nail guns are great because they make the shingle installation process a lot quicker than installing them with a hammer, they can also be potentially catastrophic if the nail gun begins to malfunction and your contractor isn't paying attention. Finally, nails should also never penetrate your roof at an angle. Installing them straight on is the only way to ensure that the shingle is fully flat and secure.
There are also some general guidelines a contractor should keep in mind when determining where to place nails on a shingle. Nails should be installed so that they're 5 5/8" above the bottom of the shingle and below the strip that seals the shingle down. The nail should also always hit both the top shingle and the very top of the shingle underneath it so that both are fully secured. Another good rule of thumb is to keep nails at least one inch away from the sides of the shingle. By following all of these nail placement guidelines along with the manufacturer's instructions, your contractor will ensure that your roof will remain secure for many years to come.