Topmount

Topmount, or top-mount, is a mounting method in which the fasteners and support hardware are applied from the top surface of the item being installed, with the fixture or its mounting hardware exposed on or above the surface. This approach contrasts with under-mount or flush-mount configurations, where components are hidden below or within the supporting plane.

In residential plumbing and cabinetry, top-mount is commonly encountered with sinks, often called top-mount or drop-in sinks. The sink rim rests on the countertop and is secured with fasteners or adhesive around the edge, and the seam is finished with caulk. This makes installation straightforward on various countertop materials, but the visible edge can be less seamless and cleaning around the seam can be more challenging than with undermount sinks.

Beyond sinks, top-mount methods appear in cabinetry hardware, electronics enclosures, and some mechanical devices. In cabinetry, mounting plates or brackets may be attached to the face or surface of a cabinet from above. In electronics, top-mount brackets secure components to the top panel of an enclosure. In mechanical keyboards, top-mount refers to a switch mounting style where the switch plate is fastened from the top of the case, a choice that can affect acoustics and flex.

Advantages of top-mount installations often include simpler alignment and replacement, while disadvantages can include a more visible seam, potentially higher profile, and greater exposure to dust and moisture at the mounting interface.