Roof Hatch
What a roof hatch has to survive
A roof hatch is the one access product that sits permanently in the weather and gets opened by someone standing on a ladder. Those two facts drive the whole specification: the seal has to hold through years of exposure, and the hardware has to work with one hand.
The galvanized KRHG and the aluminum KRHA
Karp builds two models: the KRHG galvanized roof hatch and the KRHA aluminum roof hatch. Both use heavy gauge stiffeners for added support and stability, and are finished with EPA approved electrostatic paint.
Three details are worth reading closely on the spec sheet. The push-button lock release sits on the front side of the cover, shielded from environmental elements, so the mechanism is not the first thing to fail in the weather. The gasketing is wider and more durable than a standard curb seal, to maximise the door to curb seal and ensure watertight closure. And all edges are rounded, which matters on a product that is handled from a ladder.
Standard sizes on the galvanized model are 24 x 36, 30 x 36, 30 x 54 and 30 x 96 inches, with weights from 135 to 335 pounds.
Choosing a material and sizing the opening
Galvanized steel gives strength and durability at weight. Aluminum gives a lighter cover, which shows up every time someone opens it by hand, and inherent corrosion resistance that suits coastal and high-humidity sites.
Size by what has to go through the opening, not by what fits the curb. A hatch sized for a person is not a hatch sized for a rooftop unit component, and the equipment schedule is what should set the dimension.