Undermount Bathtubs: Everything You Need To Know

The desire for a spa experience at home hasn’t lost any steam, and luxuriating in a beautiful bathtub is often at the center of that dream.

To recreate the look of a spa, there’s nothing more elegant than an undermount tub. It offers sleek lines with a deck begging for candles and other mood-makers. Are you ready to take the plunge? Find out if an undermount tub is right for you.

What Is an Undermount Bathtub?

It’s like a drop-in tub except with a flat rim. Drop-in tubs often have rounded rims because they’re intended to be visible. You can use an undermount as a drop-in tub, but you can’t always use a drop-in as an undermount.

Undermount tubs feature feet or a flat basin that rests on the floor. They’re installed with a surround and deck.

“The deck surface hides the rim and hangs over the edge of the tub into the basin,” says Chuck Khiel, vice president of Fred Home Improvement in Bethesda, Maryland. That creates a smooth transition from the surface of the deck right into the tub. “It has the same look as an undermount kitchen sink,” says Khiel.

The only part of the tub that’s visible is the basin. That sleek look makes undermount tubs so appealing.

“Most are installed because the homeowner wants a luxurious look,” says Khiel. “People want to create that spa feeling in their bathrooms.”

Undermount Bathtub Types

Just like drop-in tubs, undermount tubs are available in various shapes, materials and sizes, from basic to full-on luxury.

• Shapes. Take your pick: oval, round, rectangular, triangular. “I’ve even seen a four-foot-square corner undermount tub,” says Khiel. “I guess you’d have to bathe with your knees bent!”
• Materials. Acrylic is most common tub material and maybe the best at heat retention. “My clients tell me it’s warmer than cast iron,” says Khiel. But you can also find solid surface, enamel-coated steel and even copper. Choose from various colors.
• Sizes. There’s really no limit to what’s available. You can get a custom tub made to fit any space.
• Features. Like other tubs, undermounts can be made more luxurious with added features. They can be deep with sloped sides for comfortable soaking, jetted or even outfitted with speakers. You even can add special fixtures like hand-held shower heads.

What Materials are Best for an Undermount Bathtub Deck?

“Some type of solid surface,” says Khiel. “It performs best.” That might include natural stones or a manufactured product.

“The deck surface material typically matches the surrounding walls,” says Brandon Ewers, a sales consultant with Pirch, a product showroom for bathrooms, kitchens and outdoor spaces in La Jolla, California.

What about bathroom tile? Khiel doesn’t recommend it. “We haven’t used tile on decks for years,” he says. Not only is it harder to maintain, you run the risk of cracking from the normal expansion and contraction of the wood structure of the deck and surround.

Undermount Bathtub Cost

Undermount tubs cost about the same as drop-ins, but undermounts tend to be less expensive than freestanding tubs. Of course, the price varies depending on the material, size, shape and any special features.

“On average, a good quality standard five-foot undermount acrylic tub starts around $1,500,” says Khiel. A copper tub will cost more. “It can sell for as much as $10,000,” he says.

Undermount Bathtub Installation

It’s more difficult to install an undermount tub than a drop-in. “It has to sit absolutely level on the subfloor,” says Khiel. “Framing for the surround is done right up to the height of the tub.”

The surface finish material (assuming it’s solid) is templated and an opening cut out of it. Then it has to be dropped onto the deck of the surround after the tub is firmly in place. It all needs to be a perfect fit. If the tub isn’t perfectly level and the surround and deck aren’t built precisely, the deck surface could crack. That precision makes it a much more difficult project to DIY.

Best Undermount Bathtubs

The space you have for an undermount will dictate its size and shape. If it’s a custom size, it will cost considerably more than one off the shelf. The material you choose will affect price, too. Here are a few options suggested by Ewers:

• Good value: “Kohler makes good undermount tubs,” he says. “Their Underscore series comes in multiple sizes. They have a clean look that’s really popular, but no options for customization.” Cost: $1,200 to $7,600.
• Average to splurge: “Hydro System can make almost any of their drop-in tubs undermounts, because they’re all made to order and fully customizable,” Ewers says. Cost: $2,000 to $4,000.
• Splurge: “MTI Baths is a higher price point in general, but they have beautiful tubs that are custom-made,” says Ewers. Cost: $3,000 to $8,000.