Undermount Bathroom Sinks and Vanity Basins

Will an undermount basin work with your countertop?

An undermount basin hangs from beneath the counter, so the cutout edge is exposed and the counter must be a solid slab such as granite, quartz or solid surface. It does not suit laminate, whose core swells if water reaches it. Use the maker's cutout template, measure the cabinet's inside width and depth, and leave clearance for the drain. The faucet usually mounts in the countertop, or on the wall, because the basin itself has no deck for it.

Fitting is a precise job. The basin is clipped or bracketed to the underside of the counter and sealed with waterproof silicone, and the fixings must be strong enough to carry a basin full of water. Dry-fit first to see how much of the rim shows around the cutout, which is called the reveal, and let the silicone cure before using the sink.

Shape, depth and what is in the set

Rectangular basins give the most usable bowl for a given cutout, while oval ones have gentler corners that wipe clean easily. Sizes in titles, such as 49 x 38 x 13 cm, give the three outside dimensions. A deeper bowl splashes less, and a shallower one leaves more cabinet space below. Porcelain is hard and easy to clean, though a dropped item can chip it. Some listings are sets of two basins or a basin with faucet and drain, so read the contents before choosing.

Questions about Undermount Bathroom Sinks and Vanity Basins

Can an undermount sink go into a laminate countertop?

It is not recommended. The cut edge of laminate is particleboard that swells when it gets wet, and an undermount basin leaves that edge exposed. Choose a drop-in or vessel basin for laminate, or switch to a solid surface, stone or quartz top.

How big a cabinet does an undermount basin need?

The basin's outside length and width must fit inside the cabinet opening with room for the clips or brackets, and the bowl depth must clear the drawers or shelf below. Check the base cabinet's inside dimensions against the basin sizes in the title.

Does the basin come with a drain or overflow?

Drains are normally separate. Many bathroom basins have an overflow hole near the rim, which needs a matching pop-up drain, while basins without an overflow need a non-overflow drain. Check both the listing text and the product images.