By: Juan Jimenez
A defect that I often find during my home inspections is exposed nail heads on the roof. When the roof is installed exposed nails should be kept to a minimum, but it is unavoidable in certain situations. Most often the exposed nails are on the ridge, the flashing, an improper roof repair, or the result of a nail pop. The photo below shows to exposed nail heads. One is already rusted.
The biggest problem with exposed nails is that they rust. As the nail rusts, its diameter shrinks but the original hole stays the same size. The end result is a direct path for water to enter the attic. The leak may go undetected but over a long period of time may cause wood rot or mold. Here you can see some rusted nails with leak stains around them. Luckily, the home inspection caught these before they caused considerable damage.
All exposed nails should be properly sealed by a qualified roofing contractor. A sealant compatible with the roofing or flashing material should be applied to the nail. Some roofers will also rub two shingles together so that the granules rub off and adhere to the sealant. The intent is to prolong the life of the sealant. Keep in mind that this is not a permanent solution. The sealant will wear off and will need to be replaced regularly. Regular home inspections annually or bi-annually can spot deteriorated sealant, or nail pops that have caused exposed nail heads, and prevent costly repairs.
In short, every exposed nail head is a potential leak and should be properly sealed.