#4 Gaps in the Deck
#3 Nailing Too High
#2 Crooked Nails
#1 Air Pressure
Although many contractors do charge more for hand-nailing shingles, you'll find that our prices are quite competitive with most nail-gun roofers out there. Hiring us is a win-win for the homeowner!
"Roofing contractors who hand-nail shingles (and explain to their clients why they do so) have more work than they can handle, at a price that yields high profit...That's because the quality and durability of their work is consistently above that of their competitors." -Roofing Construction & Estimating by Daniel Atcheson (page 107)
Proper nail placement is crucial! Standard 3-tab shingles, and dimensional, laminated shingles alike, must be fastened in their designated nail zone or they will blow off. In fact, shingle manufacturers will not honor their warranty if fasteners are not properly placed and driven.
One of the biggest problems inherent with the use of nail guns, is the fact that it is hard to consistently control how deep each nail is driven into the shingle. In the morning hours, when temperatures are low, materials are stiff and more air pressure is required to properly sink each nail. As roof temperatures increase, surfaces become softer, and less air pressure is needed to sufficiently sink each nail. There are also other factors which affect how much air pressure is needed, such as cool areas where shadows fall across the roof surface, and hot areas due to adjacent reflective surfaces such as walls and windows. A conscientious roofer will be mindful of these factors. Almost 100% of the time, when we are called out to replace blown off shingles, we find that they were installed with a nail-gun.
TIP: If you do hire a roofing contractor who uses nail guns, ask to see whether they have pressure regulators mounted ON their nail guns. If they only have a regulator mounted on the compressor, they will not bother to adjust it each time it is necessary; Especially if the compressor is on the ground, as is often the case.
Improper techniques such as nailing while the gun is in motion will cause nails to get driven in at an angle, causing the nail head to cut through the shingle, which makes the roof much more susceptible to wind damage and actually voids the shingle's warranty.
Hand-nailing a roof has become a lost art these days. It is a bit slower than using a nail gun, but there is a marked increase in quality when comparing a hand-nailed roof to a gun-nailed roof. Listed below are four problems that often result when nail guns are employed to fasten shingles to the roof deck. We hope you will find the information useful whether you choose to hire us or someone else.
Notice this quote from the book 'Roofing Construction & Estimating', which is one of the books the N.M. Construction Industries Division uses as its' authority on roofing.
Roof decks, by design, have gaps and joints which can not be seen once the underlayment has been installed. A nail-gun has no "feel" to it, so an installer doesn't know whether each nail has grabbed into wood, or has slipped between a gap in the deck. Sometimes, the nailing strip on an entire course of shingles will line up with a joint in the decking. This results in nails sticking up, roof leaks, and blown-off shingles.
The gaps and joints which present a problem to the installer working with a gun are still a problem for the roofer who hand nails. The difference is, that the latter can feel when his nail hits a gap, allowing him to remove the nail, seal the hole, and relocate the nail. We pay attention to those details and that is another reason we can guarantee our roofs longer than others.