What Kind of Mortar Bed Is for Showers?

Sand Mix

• Sand mix is the ideal mortar mix for showers because of its strength and its resistance to cracking -- a common problem with mortar as it dries. Sand mix is composed of portland cement and sand. If you don't want to mix the mortar yourself, you can purchase bags of sand mix at most hardware and equipment supply stores. If you opt for bagged sand mix, you need only mix the material with the amount of water recommended by the manufacturer to create the mortar you need for the shower pan.

Latex Additives

• If you choose, you can use a latex additive in your sand mix instead of water or you may blend the sand mix with equal parts water and latex additive. The plastic polymers in the latex increase the strength of your mortar mix and, subsequently, the strength of your shower pan. Latex additives also help the mortar bed repel water. When selecting a latex additive, avoid polyvinyl acetate as it does not offer the same degree of water-resistance as other latex options, such as styrene butadiene rubber and ethylene vinyl acetate.

Hydrated Lime

• Like latex additives, adding hydrated lime to your mortar bed is purely optional. Hydrated lime further reduces the risk that your mortar bed will crack as it dries. The lime also increases the water-resistance of the finished product. Thus, it serves as an excellent alternative to latex additives. For the best results, replace approximately 10 to 15 percent of the sand mix with hydrated lime. You can use hydrated lime together with latex additives in your mortar bed if you wish.

Installing the Mortar

• Scoop the mortar mix into your shower bed with a shovel. This reduces the chance that any of your mortar mix will fall into the drain or partially cover the drain. Keeping the drain hole clear at all times, slowly spread the mortar mix across the shower bed with a flat trowel.

  The mortar bed should catch and redirect water leaks down the drain. Because of this, a mortar bed with a downward slope in the direction of the drain is beneficial. You can slope your mortar bed however you wish, but a pronounced slope isn't necessary and may make tile installation a challenge. A simple slope that measures 1 ½ to 2 inches on the edges of the mortar bed and three-eighth to one-half-inch at the drainage hole is sufficient to redirect water leaks.