Nosing is required anywhere there is balustrade or newels. Typically, nosing from a flooring company has a shorter overhang and does not have the space for trim under it. Typical floor nosing overhangs 1-1/4”, whereas Designed Stairs nosing overhangs 1-3/4” to allow for trim under the nosing. This includes apron and cove. Designed Stairs provides all of the nosing where there is balustrade or newels so that the nosing and trim will match the stair style. i.e., If the stair has square-nosed treads and square cove, the nosing, apron, and cove would also be square to match.