|Hand Nails Vs. Gun Nails|
We hand nail every shingle, the old fashioned way.
Figure 1: The nail is properly applied. The head of the nail has been driven in to the point it is fully against the shingle, pressing the shingle tightly aginst the deck below.
Figure 2: This shows what happens when an air nail gun is used, but not enough air pressure is applied. The nail does not fully rest against the shingle. This allows the shingles to flop during high winds and can cause the shingle to tear and be blown off. Because wood varies in density (there are "hard" spots and "soft" spots), setting the air pressure is guesswork, at best. Sure one could set it so for 90% of the roof, the nails are driven properly, but what happens when you drive the nail into a hard spot in the decking? You get the situation illustrated in Figure 2.
And what happens when you hit a soft spot? You get the situation illustrated in Figure 3. The soft spot in the decking offers less resistant to the nail, therefore the nail is driven in further, sometimes completely though the shingle. For all practical purposes, the nail in Figure 3 is not holding the shingle at all.
So, yes a worker could set his nail gun air setting to drive 90% of the nails into the roof properly but that leaves the 10% which are driven in improperly. Are you willing to give up 10% of your shingle to the next windstorm, simply because of poor workmanship?
What about staples? The facts are that staples simply do not provide the same type of pressure against the shingles that a roofing nail head does. Because of the makeup of shingles, it is much easier for a shingle to tear along the "head" of the staple. Once the shingle tears, it's easy for the staple to pull through the tear and release the shingle. Storm after storm has proven that more shingles are blown off of roofs that were stapled on that for those that were nailed. If you're confident your roof won't be subjected to high winds, go for it.
Hand nailing means every nail is driven in by hammer. The proper amount of pressure can be applied to make sure each nail is set properly, ensuring a good tight seal of the shingles to your decking. Figure 1 above is what you want, and the best way to achieve that is hand nailing. Many contractors charge more for hand nailing. We believe it's the only truly proper way to install shingles, therefore, we do not charge extra for it.