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Comparing Heat Retention in Freestanding Bathtub Materials

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White rectangular freestanding battub on a brown platform in front of a stone wall

Freestanding bathtubs can be made from a wide selection of materials, including acrylic, cast iron, copper, and wood, among others.

Each tub material has its unique attributes, which inevitably have an impact on their ability to maintain a comfortable water temperature. Recognizing the differences in heat retention properties among these materials can help you plan a better, more efficient, and enjoyable bathing experience.

Key Takeaways

  • Heat retention varies across different freestanding bathtub materials
  • Awareness of these variations can enhance the user’s bathing experience
  • Eco-friendly bathtub choices stem from informed decisions about material heat-retention properties

Heat Retention Properties Of Bathtub Materials

Round wooden freestanding bathtub on a wood floor surrounded by green plants

It’s important to note that factors like insulation, room temperature, and the use of a bathtub cover can influence the heat retention of any bathtub, regardless of its material. When choosing a freestanding bathtub, consider both your desired heat retention and the overall aesthetic and maintenance requirements to make the best choice for your needs.

Cast Iron Bathtubs

Cast iron bathtubs are champs when it comes to heat retention. You can absolutely soak in a hot bath longer in a cast iron bathtub. These heavy-duty tubs might be harder to install, but they’re perfect if you’re looking for the best in heat retention.

Stone Resin Bathtubs

These tubs are composed of crushed stone mixed with resin, offering a sleek, modern appearance. Stone resin tubs provide excellent heat retention. They can keep water warm for a reasonable amount of time, though not as long as cast iron.

Porcelain Enameled Cast Iron Bathtubs

Porcelain enameled cast iron tubs, like cast iron, have good heat retention qualities. They can keep water warm for an extended period, offering a comfortable bath.

Copper Bathtubs

Copper bathtubs are stunning, but they also have a knack for maintaining that cozy water temperature. Copper is a natural conductor, which means it heats up quickly and retains warmth admirably throughout your bath time. They may not retain heat as well as materials like cast iron or stone resin.

Natural Stone Bathtubs

Natural stone bathtubs, such as marble or granite, offer moderate heat retention. While they provide a luxurious look and feel, their heat retention may not be as high as some other materials.

Acrylic Bathtub Material

Acrylic tubs are lightweight and less effective at heat retention compared to denser materials like cast iron or stone resin. They may require frequent topping off with hot water to maintain temperature.

Fiberglass Bathtub Material

Fiberglass tubs have the lowest heat retention among the common bathtub materials. It’s a less durable and thinner material compared to the other contenders on this list. They can lose heat quickly, making them less ideal for long, relaxing baths.

Porcelain Enameled Steel

While porcelain enameled steel tubs are durable and easy to clean, they don’t retain heat as effectively as cast iron or other materials, often requiring more frequent hot water additions.


Wooden tubs, while visually appealing, have relatively poor heat retention properties. They tend to lose heat quickly and may not be suitable for maintaining warm water over extended periods.

This comparison table ranks different freestanding bathtub materials based on their heat retention properties, with “1” indicating the best heat retention and “9” indicating the worst:

Bathtub MaterialHeat Retention Ranking
Cast Iron1
Stone Resin2
Porcelain Enameled Cast Iron3
Porcelain Enameled Steel8

Keep Your Bathwater Warm Longer: Top Strategies


Taking steps to enhance heat retention in your freestanding bathtub will lead to longer, more comfortable bathing experiences, no matter the material. This is how to improve the heat retention of your tub during tub time:

Inline Heaters

Inline heaters, also known as circulation heaters, are a fabulous way to keep your bathwater warm. These little gadgets are installed within your bathtub’s plumbing and continuously heat the water as it circulates. This means your soak stays hot and steamy without needing to constantly add more hot water.

Inline heaters are energy efficient, meaning you won’t need to worry about a drastic increase in your utility bill. They usually come with an automatic shut-off feature to ensure that the water doesn’t overheat.

Double Walled Tubs

Double-walled tubs are built with an extra layer of material, creating an insulating effect that helps keep your bathwater hot for longer periods. They usually come with thicker walls which can provide extra durability and sturdiness, ensuring years of steamy enjoyment.

This chart compares the heat retention properties of double-walled and single-walled tubs:

 Double-Walled TubsSingle-Walled Tubs
HeatRetained LongerCools Quickly

Heat Retention in Environmentally Friendly Bathtubs

Freestanding copper tub with a white porcelain inner standing on a white rug

When considering a new freestanding bathtub, one of the key concerns might be heat retention and the material’s effects on the environment. Some eco-friendly bathtub materials do the job quite well.

One example of an outstanding eco-friendly material with excellent heat retention is natural stone. Cast from limestone and other minerals, these tubs not only look luxurious but also hold heat like a champ. They’re recyclable, which makes Mother Earth smile.

Now, let’s compare natural stone to other popular materials found in the bathtub universe:

MaterialHeat RetentionSustainability
Natural StoneExcellentHigh
Cast IronGoodModerate

Copper is a natural conductor of heat but also excels in sustainability. In fact, almost all existing copper can be recycled. As the table shows, cast iron and acrylic can’t quite reach the toasty heights of natural stone.

Cast iron does have decent heat retention, but its production process isn’t as eco-friendly. Acrylic tubs may be lightweight and budget-friendly, but they drop the ball on both heat retention and sustainability.

Selecting the best Freestanding Bathtub Materials

Understanding the heat retention capacities of various materials is essential for choosing an environmentally friendly bathtub. If you are looking to upgrade your bathroom and want to ensure that you are making a conscious effort to reduce energy consumption, this information will be particularly useful.

Tags: Eco-friendly tubs, freestanding tubs, Heat retention tubs

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