Nail popping is a result of the construction materials in a house drying and shrinking plus the natural settling of a house over time. A nail pop is an imperfection which occurs when the point of attachment of the wall, ceiling or roof sheeting to the wood framing of the house fails. This id due to movement caused by either the sheeting moving and the nail staying still, or the nail moving and the sheeting staying still. The results are the same - a nail pop.