What Are Bathtubs Made Of?
Homeowners base their choice of bathtub materials on cost, cleanability and durability. Weight, sustainability and heat retention are also important.
Bathtub materials used by the ancients would look strange in a modern bathroom. The Babylonians coated bricks with a mixture of bitumen and limestone to make them waterproof. Roman tubs were made from terra-cotta bricks and tiles, and the Chinese soaked in tubs hewn from tree trunks.
By contrast, many modern bathtub materials come from a factory. That doesn’t make them any less attractive than the natural materials people have used through the ages, but they are definitely more affordable and easier to keep clean.
Raf Howery, CEO and founder of Kukun, who parlayed his fix-and-flip expertise into a data-driven home improvement platform for design-conscious homeowners, doesn’t think any bathtub material is “best.” But to him, some score higher than others on his three most important factors: durability, cost and cleaning. Homeowners should also consider weight, heat retention and sustainability.
What People Look For in Bathtub Materials
Some people choose a bathtub based on aesthetics. Others are more interested in comfort, and still others mostly price. A typical priorities list would include:
- Durability: How well does the bathtub material resist impacts, and will it prevent flexing and cracking?
- Ease of cleaning: How hard will it be to wipe off that bathtub ring? How susceptible is the material to hard water, rust and other types of bathtub stains?
- Weight: Even a lightweight bathtub is heavy when full, but one made of a super-heavy material can put enormous stress on the floor.
- Thermal conductivity: People who like to soak for hours will appreciate a material that retains heat. Those who limit their time in the tub may not care.
- Sustainability: Does the material come from a sustainable source? Is it recyclable, or will the bathtub just slowly deteriorate in a landfill when its service life is over (assuming no one claims it for container gardening)?
- Cost: Decide what you’re willing to spend before you shop.
Fiberglass, Howery says, is the least expensive material. These are manufactured by forming fiberglass resin into a bathtub shape and coating it with gel-coat resin.
- Lightweight and easy to install.
- Easy to repair when damaged.
- Sand, a sustainable material, is the main ingredient in fiberglass.
- Flexible and prone to cracking and scratching. Howery says fiberglass tubs often feel unstable.
- Porous enough to absorb water, so stains can be difficult to remove.
- Color can fade over time, especially after prolonged and repetitive cleaning.
Similar in appearance to fiberglass, acrylic is manufactured by heating a sheet of plastic resin, forming it into a bathtub shape and reinforcing it with a fiberglass coating. Howery calls acrylic moderately expensive.
- Completely non-porous. Does not support mold growth and resists staining.
- Lightweight and suitable for installation anywhere.
- Easy to clean, although abrasive cleaners are not recommended.
- Howery notes acrylic does not absorb heat. Water stays hot, which makes acrylic tubs great for soaking.
- Limited sustainability. Petrochemicals form acrylic resin.
- Although not as flexible and prone to cracking and scratching as fiberglass, acrylic can still feel unstable.
Cast Iron Bathtub
The design of the modern bathtub owes its origin to John Michael Kohler, who added legs to a cast iron horse trough and coated it with hard enamel to create the first clawfoot tub. To make a modern cast iron tub, molten iron is poured into a mold. Then a hard enamel coating is applied.
- Great durability. Highly resistant to impacts and scratches.
- Good heat retention. There’s a reason why some of the best soaking tubs are made of cast iron.
- Easy to clean and maintain. The hard enamel coating is non-porous and stain resistant.
- Designer friendly. Howery notes various colors and styles are available.
- Sustainable materials. Cast iron tubs last a long time, and the materials are all recyclable.
- Heavy. Cast iron tubs weigh between 300 and 500 pounds without water. According to Howery, installation is “difficult, elaborate and costly.”
- Expensive. Howery says that cast iron tubs are among the priciest ones out there.
Enameled Steel Bathtub
A more lightweight alternative to cast iron, porcelain enameled steel is still a heavy bathtub material. Offering what Howery characterizes as “extremely limited” design options, it’s typically molded into alcove and other built-in tub models.
- Durable and long-lasting.
- Scratch and stain resistant. Easy to clean.
- Good heat retention.
- Expensive compared to other materials.
- Enameled coating can chip and wear through, and the steel can rust.
Solid Surface Bathtub
A relatively new addition to the market, solid surface bathtubs are made from various types of polymers.
- Non-porous, stain resistant and easy to clean.
- Excellent heat retention.
- Stylish with high-end appeal.
- Among the more expensive bathtub materials.
- Not as heavy as cast iron, but still heavy and may require extra structural support.
Cultured Marble Bathtub
Made from a mixture of limestone and resin and coated with a layer of gel coat, cultured marble is a class of stone resin materials fabricated with natural crushed stone.
- A wide selection of styles and colors is available.
- Longer lasting and more durable than other materials.
- Non-porous and easy to clean.
- More expensive and not as widely available as other materials.
Reminiscent of Roman terra-cotta baths, ceramic tubs are lined with ceramic tiles. This type of tub can be customized into any shape.
- More design options than any other material.
- Can be a low-ticket item when budget tiles are used.
- Can be difficult to maintain. Grout is porous and can support mold if not cleaned regularly.
- The irregular tile surface can be uncomfortable, making this type of tub less than ideal for soaking.
Most top-of-the-line bathtub materials are natural ones that people have used through the ages. They include natural stone, copper and wood, and are just as likely to be custom-made as purchased off the shelf.
If you’re looking for something exotic and cost is no object, you might consider a crystal tub. Tubs hewn from solid chunks of amethyst and quartz are out there, but beware: Their price tags are in the millions.