When hand nailing roofing shingles is better?

We have to say most of the time hand-nailing will have a slight advantage over gun nailing shingles.  Although I would almost never hand nail a roof, mostly because the advantages do not outweigh the increased time for any experienced roofer.  However there are more crews every year that go to strictly hand nailing because of the percieved quality advantages.  For many companies it is a marketing decision more than a decision driven by the need to install a superior product.  This plays into a reoccurring theme we strongly believe in the product you put on your roof in part the quality of the shingles and materials and part the quality of the labor used to install them.

So why is hand nailing roofing shingles superior?

Simply put hand nailing eliminates errors than gun nailing can create, not that it is a given they will happen.  Perhaps the biggest single point to make here is that when you are gun-nailing it is quicker for the vast majority of roofers out there, and you can make mistakes you don’t even realize.  The likelihood of an inexperienced roofer making mistakes while gun-nailing is near 100%.  Let’s explore a couple common mistakes made while installing asphalt roofing shingles with an air nailer.

Problem Explanation Picture
 
Over Driven Nails When  the pressure on compressors is not set properly roofing guns coil nailers are so powerful they can drive nails through the shingles and actually indent them.  This causes a shingle failure and leak point often times all the way through to the deck because of the pressure and cushioning effect on the deck below.  This is near impossible with hand-nailing because when your hammer hits the shingle the pressure on the nail head DRAMATICALLY decreases, you’d have to have a ball-pin hammer to drive a nail this far by hand.    It is possible to set pressure correctly and regulator at every gun dramatically help.  The problem is individual gun regulators are not as common as they should be,  and weather dependent your compressors need to be adjusted to ensure the proper pressure is being applied to the nails. Roof-overdriven-nails-440x330
Side or angle- Driven nails Driving nails at an angle or not directly square can result in a poor quality roofing installation. While it may not matter when wind driven rain pulls up on the shingle tab portion this can create just enough of a gap to get a leak, additionally if overlooked and not hand pounded flush, later in the roofs life this can lead to nail pops damaging the shingle above.  Seen in the upper left of the picture on the right nails driven an an improper angle can actually rip or tear into the surface of the shingle creating future failures.  Side Driven Nail hurts roof shingles
Under Driven Nails You will almost never under drive a nail when hand nailing because you have physical feedback from your hammer when the nails has been properly sunk.  It is possible to under drive with a nail gun.  The most common way this happens is simply from too many guns being hooked up to the compressor.  If four guns are going and the pressure gets too low to properly drive the nail, while the gun may still fire the nail won’t sink completely.  If you are going fast it is easy to miss this.(Many times this happens and you actually catch it) and “flush it down” to the shingle.  While this is an extreme example at the right it is a good example of what can happen over time if the nail didn’t end up penetrating the roof deck properly. Under Driven Nails
Improper Nailing Locations  The most common improper location for nailing asphalt roofing shingles is high nailing.  Simply put this is placing the nail above the nail line.  This is a critical error because to nails than do not penetrate both layers of shingle and this is the number one cause for blow offs.  However, we also see low nailing and all together too many nails as well.  IN GENERAL (not as a rule)  I see many more mistakes on gun nailed roofs when is comes to nail placement than hand nailed roofs.  This is because it is easy to reach and nail with a gun, and go fast causing mistakes.  When you use one hand to place the nail and the other to hammer nail placement mistakes are much harder.  AS LONG AS YOU KNOW WHERE TO PLACE THEM IN THE FIRST PLACE! high nailed
Mistakes – Nail Misfires This is a common symptom  of inexperienced gun nail roofers as well.  Guns can be set to fire when you press them down and because of this a tired or rushed roofer can misfires the gun simply when they lean back or put a gun down to re-position themselves.  These are fixable if you aren’t lazy but can require some real effort if done in the middle of an installed roof.  Sometimes they are just ignored, and turn into a leak 5-10 years later. Air nailer shingling better hand nailing
 

 Conclusion: Should we all just suck it up and hand nail?

If you look at the table above you may come to the conclusion – shoot with all the possible “mess-ups” when using a power nailer why not just hand nail?  We are being a little picky here but all of these problems are a reality.  That being said there are 1000′s of roofs installed every year using power nailers with no ill-effects.  With an experienced crew that truly CARES about quality and knows what they are doing power-nailing is fine.  If time and money were no object maybe I would insist on hand-nailing but expect to pay a higher price.

Disagree?  Something to add?  Comment below.