I have also torn off both hand nailed roofs and gun nailed roofs.
Hand nail vs gun nail roofing.
When you use a gun usually a third or under driven a third or over driven and a third or correct.
Hand nail installers are quick to feel a nail miss the wood sheathing while nail gun operators have to rely on sounds and intuition.
Most times the roofs that have been put on with a nailer all nails stay in the wood when tearing off.
Over or under pressurized nail guns can result in nails that are either driven too hard or not driven deeply enough.
A good contractor will inspect the roof sheathing after it is removed to determine if nail misses are likely to occur.
If this is the case hand nailing should be preferred over the use of a nail gun.
Taking into consideration the same size nail is used.
However most manufactures claim that either method is a viable option.
A hand nailed roof is hands down a better roof than using a nail gun.
Hand nailing can be fast but the same man at the same skill level doing the same job will perform faster using a gun and compressor.
I have roofing crews that can hand nail just as fast as a gun.
But it s important for these roofers to always test their tools before using them.
As far as it taking longer.
There just are not many shinglers that have the skill level to keep up with a man with a gun.
Hand nailed roofs most nails come out during tear off.
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A hand nailed roof trump s a gun nailed roof any day.