What is the primary characteristic of the waterfall installation method?

The primary characteristic of the waterfall installation method is that the carpet falls over the bullnose of the tread. This technique involves allowing the carpet to drape down from the edge of the stairs, which not only creates a visually appealing transition but also provides protection to the edges of the stairs. This style helps in reducing wear and tear on the carpet and enhances safety by covering potential tripping hazards created by exposed edges.

The waterfall method is particularly useful in residential settings where aesthetics and safety are both important, as it allows for a smooth finish that complements the home's interior design while offering a soft landing surface on stair edges.