Dear Angie: My home needs a new roof. Which is better: hand-nailing or using a nail gun for the shingles? Does it matter? — S.A., Norman, Okla.
Answer: Let me start by answering your last question first. Technically, it does not matter whether a roofer hand- or gun-nails the shingles. Both methods are approved by roof manufacturers, so there is no "right" or "wrong" way.
That said, this is certainly a topic about which many roofers are very passionate. Improperly nailed roofs can be more susceptible to leaks and damage from storms. Ideal nail placement on roof shingles is limited to a very small area. If the nail is driven outside of that area, it could impair the roof and void the manufacturer's warranty.
Because of that, many highly rated roofers on Angie's List tell me their preferred method is to hand-nail roofs. By doing so, roofers can ensure the nail is properly placed and is nailed in at the correct depth; flush with the shingle and not over- or under-driven.
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Though this can be achieved with nail guns, many roofers tell me there is more room for error, especially if the person doing the nailing is inexperienced or is rushing through the job.
Contractors who nail by hand say they can feel whether the nail catches the wood but don't get that same feeling with a nail gun. Nails driven between boards or outside the ideal placement area will loosen over time, eventually causing raised shingles or leakage. If there is a failure with the roof and you make a warranty claim, expect the manufacturer to check the nail pattern to ensure that the nails are flush and placed properly.
The advantage to nail guns is that they reduce the amount of time and effort to put on a roof. As one roofer told me, a nail gun never tires, unlike a worker who's been hand-nailing all day on a roof where it's 100 degrees.
Still, there are a lot more variables to gun-nailing. It is important that the nail gun compressor settings be adjusted regularly and that the equipment is maintained properly. To account for variations in temperature, wood type and roof type, the air pressure for nail guns must be adjusted frequently and accordingly. The angle of how the roofer holds the gun is also important. If it's off, even slightly, the nail can go in crooked.
The bottom line is that both methods have their flaws. The most important thing you can do is choose a roofing contractor who has a proven track record, will explain clearly, in writing, his or her method for nailing, and will offer a comprehensive warranty for the work and will stand behind the warranty should something go wrong.