Figure 6-51: one piece tubs and showers  (C) J Wiley, S BlissGuide to Choices of Tubs and Tub/Shower Units

  • TUBS & TUB REPLACEMENTS or RELINERS - CONTENTS: Guide to choosing & installing plumbing fixtures, sinks, tubs, & faucets for kitchens & bathrooms. Porcelain-Enameled Cast Iron Tub Properties. Porcelain-Enameled Steel Bathtub Properties. Fiberglass Bath & Shower Enclosure Properties & Recommendations. Acrylic Bathtub & Shower Properties
  • POST a QUESTION or READ FAQs about choosing & buying a bathtub - types, materials, features, or about buying a shower surround and pan assembly

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Bathtub & shower design & product choices:

This article discusses the types of bath tubs and tub/shower units, giving the pros and cons of each, including porcelain-enameled cast iron bath tubs, porcelain enameled steel bathtubs, fiberglass bath tubs and fiberglass shower enclosures, and acrylic bathtub and shower enclosures. Our page top photo shows the website editor bathing in a rustic bath tub [in 1944]. More modern, comfortable bathtub choices are available and are described here.

Page top photo: the website author having his first out-door bath in a wash tub, Dunnsville Virginia, 1943.

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Guide to Choices of Tubs and Tub/Shower Units

Japanese style bath tub installed in a Minnesota home (C) Daniel Friedman Steven Ostrow

Our photo (left) illustrates a Japanese style bathing tub installed in a Minneapolis home.

The classic tub for many homeowners is still the rock solid, cast-iron model with a porcelain enamel finish. Driven by cost savings on both materials and installation, manufactures have introduced lighter-weight alternatives using molded plastics (Table 6-10).

While not as hard as the original iron tubs, the plastic alternatives have improved over the years and provide great flexibility for designers

Table 6-10: Tub and Shower Materials & Properties (C) J Wiley, S Bliss

Table 6-10

[Click any image or table to see an enlarged version with additional detail, commentary & source citation.]

Most units include integral soap dishes, ledges, grab bars, and other molded features that help bathers and also provide rigidity to the unit. For new construction, most units are one-piece, creating a seamless, leak-free bathing enclosure (see Figure 6-51).

Figure 6-51: one piece tubs and showers  (C) J Wiley, S Bliss

Figure 6-51

Retrofit tub/shower units typically have four or five pieces that fit together with sealant.

The fewer pieces, the better, as fewer seams means less risk of leakage, less seams that an installer may caulk (a potential site for fungal growth), and a more attractive surface.

Porcelain-Enameled Cast Iron Tub Properties

Cast iron claw foot tub ca 1885 (C) Daniel Friedman

The classic tub material is very solid, very quiet, and resists scratches, chips, and stains.

On the other hand it is very heavy, cold to the touch, and available only in pretty basic shapes.

It does not easily mold into the body-hugging contours found on many of the plastic units.

Although the surface is the most durable for molded tubs, it is not indestructible. If homeowners use abrasive cleansers and pads, over time the finish will dull.

Our photo (left) illustrates an 1880's cast iron claw-foot tub installed by the editor (DF) during a renovation in Wappingers Falls, NY.

Porcelain-Enameled Steel Bathtub Properties

Porcelain enameled steel bath tub (C) Daniel Friedman

Porcelain enamed steel used to build a bath tub weighs less than cast-iron and feels less substantial, as the material has some give under the weight of water and bathers. It is also more prone to chip than cast iron.

Our photo (left) shows a porcelain enameled steel bath tub still in good condition in a 1960's home. [However some older porcelain on teel bath tubs we have inspected were prone to chip and then rust damage - Ed.]

A hybrid alternative is American Standard’s Americast, which is a porcelain enameled steel reinforced on the back with a cast polymer.

The material is stiffer and quieter than regular enameled steel, but it is half the weight of cast iron. The company literature claims that the surface is more durable and slip resistant than standard porcelain enamel and that the composite layer helps retain heat.

Fiberglass Bath & Shower Enclosure Properties & Recommendations

Bath tub re-lining project (C) Daniel Friedman

Bath Tub Replacement / Re-Liner Options

Our photo (left) illustrates the renovation of a badly-worn cast-iron porcelain lined bath tub in a 1920's home restored by the editor. The tub was re-lined using a modern plastic-type material that matches the profile and appearance of the original tub that was left in place beneath the liner.

New Fiberglass Shower or Bath Tub Properties

Half round shower enclosure (C) Daniel Friedman

Also called FRP (fiberglass-reinforced plastic), or gel coat, this material is manufactured by spraying a thin coat of gel coat into a mold followed by several layers of polyester resin mixed with chopped fiberglass. Between coats, fabricators typically reinforce tub and shower walls and floors with blocks of wood or corrugated cardboard.

One of the premium manufacturers of fiberglass tubs, Aqua Glass, uses a layer of rigid polyurethane foam between fiberglass coats, creating a stiffer assembly that helps the tub retain heat and deadens sound.

The company also adds an antimicrobial compound to the gel coat to inhibit the growth of bacteria and mold. With any FRP tub, the thickness of the gel coat and thickness of the overall lay-up affect its strength and durability.

Our corner shower enclosure (photo at left) with a round gliding door provides ample bathing space in a small bathroom. Photo courtesy Galow Homes.

One way to assess quality is to look for tubs that conform to the voluntary standard ANSI Z-124, which requires that a random sampling of acrylic and gel-coat tubs undergo a variety of durability tests.

The thin gel coat can be damaged, but it is relatively easy to repair with gel-coat repair kits sold in marine and automotive stores. Color matching, however, can be difficult. Also if a chip is not repaired quickly, water can penetrate to the backing and cause the damage to spread.

Overall, a gel-coat surface is less scratch- and stain-resistant than acrylic. Abrasive cleansers must not be used. Many manufacturers recommend an auto wax or special fiberglass bath wax available from tub suppliers.

A proprietary FRP composite called Vikrell™ (Sterling/ Kohler), makes tubs from a mix of resin, color, and chopped fiberglass molded under compression.

The material has no gel coat or layers to chip or crack and has color all the way through. The manufacturer claims that the high gloss finish has the durability of acrylic and the ease of repair of fiberglass at roughly 40% less than the cost of acrylic.

Acrylic Bathtub & Shower Properties

See description (above), under sink materials. One interesting high-end product called Armacryl (Kallista/Kohler) uses a thick clear layer of acrylic over a second color layer.

Like other acrylic fixtures, it is reinforced with a fiberglass backing. The result is a lustrous and thick acrylic finish with excellent durability.


This article series discusses current best design practices for kitchens and bathrooms, including layout, clearances, work space, and accessible kitchen and bathroom layout, clearances, turning space, grab bars, controls, etc. We include advice on choosing and installing kitchen countertops, cabinets, and kitchen or bathroom flooring, sinks, and other plumbing fixtures and fixture controls such as faucets. A list of kitchen and bath product manufactures and sources is included. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

-- Adapted with permission from Best Practices Guide to Residential Construction.


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