How to select tiles for a shower.

Many types of ceramic, porcelain tiles are suitable for showers. There are some important performance factors to consider, but you can advise your customer starting with tile material, then size, shape, color and layout. Choosing the right tile for showers starts with focusing on the specific areas where your customer intends laying tile.

Important Note: Because showers are (very) wet areas it is highly advisable to contract a professional installer to do a shower. Showers require much more than simply laying tiles. Careful sloping, waterproof membranes and grouting are essential.

Shower Floors

Good tiles for shower floors should be slip-resistant, impervious to water and suitably sized for the space and the slope of the shower tray.

Many porcelain tiles are popular options, while most glazed ceramic tile is unsuitable, because it's too slippery (unless the tiles are very small).

No tile installation is truly waterproof, and it's not necessary to have tile classified as impervious, unless the shower is outdoors and subject to freezing temperatures, but the least impervious tiles (classified as non-vitreous) generally aren't suitable for shower floors.

Shower floor tile size affects both design flexibility and slip-resistance. Shower floors slope toward the drain and often have multiple planes to direct all the water to a single point. This makes a difficult business of laying tile in a standard shower pan with large format tiles. Mosaics or smaller tiles are recommended because they conform to the slopes. Smaller tiles also involve more grout lines than larger units, and because grout is fairly rough this means greater slip-resistance.

There are exceptions however; a barrier-free, shower or 'wet room' might use large-format tiles covering the floor with a single sloping plane leading to a linear, trench-style, drain. The large tiles and one-way slope create a nice surface for movement and the tiles can continue right into the main bathroom area. The most important consideration here is slip-resistance. Slip-resistance for tile surfaces is rated by a measure called the coefficient of friction (COF); large tiles used in wet areas like shower floors should have a COF of 0.6 or higher. 

Shower Walls

Good tile for shower walls includes pretty much any type suitable for wet locations. Glazed ceramic and porcelain tile are the most commonly used, from the common 10x10cm white squares to narrow 7x21cm 'subway' tile right the way up to large format tiles of almost any size, provided the installer is up to the task. Glass and stone also make good tile for shower walls. Stone tiles should be easy to clean and resistant to staining from mineral content in water. As for grout joints, the benefit of slip-resistance doesn't apply to walls so the question of size comes down to wall size, layout and shape, as well as maintenance: the gritty surface of grout is harder to clean than the smooth tile faces.

Proportion is critical with all wall tile, and this is particularly true with shower enclosures.
It has become increasingly popular to choose matching or complimentary mosaics to add detailing to shower enclosures. Although these are more expensive per area you don't need much and they can really make the space special.