A system comprising a roof of a building structure and a support structure (200-A) for mounting equipment on the roof, the support structure (200-A) comprising: at least one support rail, for supporting the equipment; one or more standoffs, coupled to the at least one support rail, for maintaining the equipment away from the roof; and wherein: the support structure (200-A) is preassembled off the roof for installation on the roof as a single unit; no tie-down is present to retain a lower end of the support structure (200-A); and the support structure (200-A) penetrates the roof of the building structure (100-E) only at an apex of the roof, the support structure further comprising: a main support comprising: a load-bearing member having a first end (210-A), a second end (210-B), and an interface member disposed between the first end (210-A) and the second end (210-B), wherein the interface member has a face that mates with an apex of the roof, and wherein the interface member is larger than a hole or a gap in the apex of the roof through which the second end (210-B) of the load-bearing member passes; the interface member provides at least one of a pivot point for any torque loads from the equipment, a physical support of a weight load of the equipment, and a weather shield for the gap in the apex; and only the second end of the load-bearing member extends beyond an imaginary plane formed by the interface member in order to penetrate the apex of the roof on which the support structure is installed. at least one support rail, for supporting the equipment; one or more standoffs, coupled to the at least one support rail, for maintaining the equipment away from the roof; and wherein: the support structure (200-A) is preassembled off the roof for installation on the roof as a single unit; no tie-down is present to retain a lower end of the support structure (200-A); and the support structure (200-A) penetrates the roof of the building structure (100-E) only at an apex of the roof, the support structure further comprising: a main support comprising: a load-bearing member having a first end (210-A), a second end (210-B), and an interface member disposed between the first end (210-A) and the second end (210-B), wherein the interface member has a face that mates with an apex of the roof, and wherein the interface member is larger than a hole or a gap in the apex of the roof through which the second end (210-B) of the load-bearing member passes; the interface member provides at least one of a pivot point for any torque loads from the equipment, a physical support of a weight load of the equipment, and a weather shield for the gap in the apex; and only the second end of the load-bearing member extends beyond an imaginary plane formed by the interface member in order to penetrate the apex of the roof on which the support structure is installed. the support structure (200-A) is preassembled off the roof for installation on the roof as a single unit; no tie-down is present to retain a lower end of the support structure (200-A); and the support structure (200-A) penetrates the roof of the building structure (100-E) only at an apex of the roof, the support structure further comprising: a main support comprising: a load-bearing member having a first end (210-A), a second end (210-B), and an interface member disposed between the first end (210-A) and the second end (210-B), wherein the interface member has a face that mates with an apex of the roof, and wherein the interface member is larger than a hole or a gap in the apex of the roof through which the second end (210-B) of the load-bearing member passes; the interface member provides at least one of a pivot point for any torque loads from the equipment, a physical support of a weight load of the equipment, and a weather shield for the gap in the apex; and only the second end of the load-bearing member extends beyond an imaginary plane formed by the interface member in order to penetrate the apex of the roof on which the support structure is installed.