What happens if siding nails are under driven?

When siding nails are under driven, it indicates that they are not fully seated against the siding material, which can lead to several potential issues, such as compromised holding power and vulnerability to moisture. Setting the nails snugly is essential as it helps ensure that they are properly anchored while also allowing for the expansion and contraction of the siding material. This snug fit influences the longevity and efficiency of the installation, as it minimizes the risk of water infiltration and damage that could occur if the nails are not adequately secured.

The other options suggest actions that either do not address the problem appropriately or imply allowances that could lead to further complications. Thus, adjusting the nails to be snug is the correct course of action to maintain the integrity of the siding installation.