The danger of nail guns
You probably haven’t spent much time thinking about how your roof was installed. It’s shingles and nails, right? What’s complicated about that? Well, there’s a little more to it.
If you’ve ever had a shingle fly off your roof after a storm, it could be because your installer used a nail gun instead of hand nailing your shingles.
Nail guns are popular because they shorten training time and reduce effort. It takes time and practice to become proficient at hand nailing, while nail gun productivity can be achieved almost immediately. In spite of this apparent advantage, we hand nail all our shingle roofs.
The main reason is that we have more control over the depth of the nail, which must be flush with the surface of the shingle. This means the nail can’t be over-driven or under-driven.
Roofers who use nail guns will start the nail gun compressor in the morning, at the beginning of the day. Of course as the day goes on, the temperature gets warmer and the installer needs to adjust the pressure to compensate for temperature variations. What ends up happening is the installer doesn’t adjust the compressor because it’s a hassle to frequently go up and down the ladder. Instead, they’ll usually set the compressor extremely high which drives the nail too deep into the shingle. This also saves time for the installer who would normally have to hammer raised nails to “finish.”
Unfortunately, over-driven nails tend to blast completely through the shingle, creating a problem that remains unseen until high winds test the installation. Six flush nails are required to achieve a wind rating of 130 mph. If any of the nails are under-driven, you’re going to lose shingles in the next wind storm. It’s a big problem in Oklahoma because of our high winds.
Sometimes installers who use nail guns will compensate by increasing the amount of nails per shingle. However, this just increases the amount of deck penetrations which weakens the shingles over time due to thermal expansion and contraction.
The ideal nail placement is limited to a very small area. When a nail is driven outside of that area, the shingle’s wind resistance is reduced and the manufacturer’s warranty may be invalidated. Shingle manufacturers have certain guidelines they want installers to follow. They’re very particular about how many nails go into each shingle and the placement.
Proper nail placement is certainly possible when using a nail gun, but tends to be considerably more accurate when hand nailing.
That’s because with hand-nailing, you can feel when the nail misses a board. It’s a feeling you don’t get when using a nail gun. Nails driven between boards are more likely to be overlooked, which will cause raised shingles or leaking.
A lot of our installers are so used to hand nailing that it’s a comfort issue for them. They can feel when the nail is in the right place and they’re more confident in the work they do. They also have the skill and practice to hand-nail quickly. It’s intuitive after a while. They know where it’s supposed to go and what it’s supposed to look and feel like.
Sure, it takes a little more time for new installers to get trained on hand nailing, but we really feel it’s well worth the time and effort to ensure we’re building quality roofs that will withstand most anything Oklahoma weather throws are at.
If you’re interested in learning more about our roof nailing process or would like a quote, please contact us at 359-3951.