A fastener installation tool and related method are provided for installing fasteners in boards, where the boards are installed immediately adjacent one another, without a gap established therebetween. The tool can include an alignment projection that projects a preselected distance downwardly from a lower surface of the tool. The alignment projection can be disposed between opposing corners of first and second boards to install a fastener without establishing a gap between the boards. This construction can be suitable for installing boards constructed from materials that shrink over time, such as wet, treated lumber or other materials, and even non-shrinkable boards where tighter spacing is desired. A related method of installation is provided.