This small settlement is inhabited by only 2 people. Sierra Petrovita, a Nuka-Colaaddict, who uses her home as a place to collect Nuka-Cola merchandise and memorabilia and Ronald Laren, the other inhabitant, who is only staying in Girdershade because of his crush on Sierra.
Girdershade consists of two houses under a damaged highway overpass, and has some minor barriers in place.
A random encounter of a scavenger offering the player a Nuka-Cola Quantum will mark Girdershade on their map if it hasn't been discovered yet. The scavenger will mark it regardless if whether or not the player purchases the Quantum from him.