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I have a colonial built in 1913 and I live in NYS. My roof was just completed today and I have exposed nails across the entire roof!

image of roof nails

It was not like this before. When I asked the contractor about it, he said this is normal, but I'm having a difficult time accepting this answer. I have included a picture to show what the entire roof looks like from the inside of the attic.

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That's perfectly normal. I would have preferred to see the vertical joints in the sheathing line up with the rafters, but that's about it. Roofing nails actually should come through about a quarter inch - I'd be more concerned if they didn't.

  • It looks like a majority of the nails are coming through 3-4". Is that also normal? – Darrick Herwehe May 8 '15 at 12:49
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    @DarrickHerwehe - The nails coming through 3-4" are for the sheathing (thus I would have preferred them going into rafters). It certainly won't harm anything unless as Tyler Durden mentioned, you stand up suddenly. – Comintern May 8 '15 at 12:53
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    It is better to have too much nail than not enough. – DMoore May 8 '15 at 12:57
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    It would be difficult at best to hit every rafter while roofing. It's possible they used longer nails because they needed them at one point in the project and rather than worry about where to change the nails they just used them for the whole project. As stated there's nothing wrong with the nail poking through a bit extra. – Dano0430 May 8 '15 at 15:18
  • This roof was originally wood shingled over spaced furring strips. They've laid OSB sheeting on top to handle standard asphalt shingles. The nails you show are probably 10 penny, driven through to attach the sheeting to the spaced furring strips that wood shingles are normally attached to. The rafter is that thick piece of wood to the right of the picture that the furring strips are laid across.. – Fiasco Labs Jun 18 '16 at 6:17
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I think there is a big problem with nails extending through the sheathing into the attic space. When the temperature falls below 32 degrees the humidity in the air will condense on the nails (frost). Above 32 degrees, the frost melts and water soaks back up into the wood (capillary action) and over a few winters you will have a moist wood surface - and a mold problem. That is the cause of my problem, I think. I know proper attic ventilation - air flow - is suppose to eliminate humidity but humidity is in all the outside air. The humidity is increased by improper ventilation from bathrooms etc, but air flow does not eliminate or reduce humidity in the air. Temps around 32 and humidity around 70 to 90 will result in frost and water and mold. Nails extending through the sheathing seem to be source of a serious problem in my attic. Other opinions most welcome.

  • Although your idea sounds logical it is quite normal for nails to protrude. – Ed Beal Dec 19 '16 at 14:05
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Once you fully nail through the roofing wood to the other side you end up with a stress fracture for moisture from both sides.nails should nit reach the full thickness to the floor roofing material and if its a new home structure as it makes the electricians and heating /cooling people work slower at times too.

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Nails should never go through the plywood, water does go under the shingles and rust the nail thus making it thinner, more water to go through, the correct nail length should be the sum of the shingle thickness plus the underlying materials minus 1/4 inch...it is strange that protruding nails are thought to be normal! it is a common error in American building construction methods...you will not find this elsewhere in the world!

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