Creating a Mortar Bed for a Shower Installation using Sakrete Sand Mix

So you’ve finally decided that you need a second shower in the house. Good idea. You’ve scoped out of the spot, taken all of your measurements and rounded up all of the supplies. If you’re reasonably handy and have access to the internet you should be able to figure this out.

Since the purpose of this blog is talk about the mortar bed, we will not be addressing or advising on any of the other concerns such as plumbing, walls, shower doors and a host of other things.

Before building the mortar base insure that the substrate that the mortar bed will be placed over is structurally sound and has the ability to support the weight of the mortar bed and the remainder of the project. Like with any job getting the base correct is essential. In this case you need a good solid mortar bed to support everything. Sakrete Sand Mix is a prepackaged cement mix ideally suited to this application. Don’t be fooled by the words “sand mix”. This product is actually a high strength mortar made with sand and portland cement which I will henceforth refer to as “mortar”. As a side note, Sakrete Sand Mix can be used in many other projects like a bedding mix for brick and flagstone walkways or a topping mix for rejuvenating old concrete surfaces.

There are two ways to install a shower. One is by using a preformed shower pan. Unless your significant other is dead set on having tile, this is the easier way to go. However if there is no talking him or her out of tile, then by all means you can lay the tile on the mortar bed. Either way you still need the Sakrete Sand Mix.

Since water tends to run downhill you will need to make sure that the tile drain is at the lowest point. Typically the drain is dead in the center but you can put it anyway as long as it’s in the lowest spot. The important thing is to begin placing your mortar at the drain and work your out and up. Typically ¼” per foot is the amount of slope required to get the water to cooperate.

The overall thickness of the mortar depends on a variety of factors. If you are using a preformed shower pan, the manufacturer of the pan should provide instructions as to how thick the mortar bed needs to be. If you are installing tile, the mortar bed should be 2-3 inches thick on the outer edge and slightly less at the drain.

When mixing the mortar use only enough water to obtain a “dry pack” consistency. A good way to tell if you have the right “dry pack” consistency is to make a ball with the mixed mortar similar to a snowball. You need just enough water so this ball holds its form without breaking, if so you’ve added the correct amount of water. By the way please wear gloves when messing with mortar. Some folks have more sensitive skin than others but overexposure can cause burns and irritation.

Once the mortar has reached the “dry pack” consistency place the mortar in position and using either a wooden float or a stout rubber trowel shove the mortar into place. Unlike concrete this type of mortar isn’t troweled with the intention of putting a nice smooth finish on the surface. The intent is simply to push hard on the trowel until all of the mortar is tightly in place and relatively smooth. Once the mortar is in place allow it set overnight. Once the mortar is set you can continue the process of placing either the shower pan or tile.

(Note for tiling: Tiling should begin within approximately 16 hours of the mortar bed installation. After 24 hours, the mortar bed enters a green state and should not have tile adhered to it for 28 days.)



  • Ben C

    If I apply red guard to the mortar after the 16 hour waiting period, do I still need to wait the 28 days before applying tile?
  • Lee-Technical Service

    Ruby, we recommend that you follow ANSI 108 Ceramic Tile Installation for a Mud Bed. This will give you all the criteria for various installations. These are the guidelines that we follow and where we get our information. ANSI American National Standard Specifications for the Installation of Ceramic Tile.
  • Lee-Technical Service

    Billy, you typically moisture curing a product for 3 days. Then leave it alone for the rest of the 28 days.
  • Lee-Technical Service

    Brandon boyd, you cannot set the tiles in the freshly packed material. They will not stick to a dry-pack well enough. You can start thin setting the tile on the surface within 16 hours of placing the dry-pack.
  • Ruby

    We have a recessed shower with a mortar preslope and will be installing tile. If we follow your recommendation of, "mortar bed should be 2-3 inches thick on the outer edge and slightly less at the drain". This will take up all of our recess. Why do you recommend this thickness? Can we make the top mortar bed thinner?
  • Brandon boyd

    Can you place the tile directly on top immediately after you set it or do you need to wait till the next day and apply thinset to the bed with the tile?
  • Lee-Technical Service

    N C, when mixed to a dry-pack consistency, you can usually start grouting the shower within 16 hours of application. As far as how soon you can use the shower, you will need to consult the manufacturer of the grout for that information. The grout between the tiles would be the last product installed, so it is up to them as to how long you will need to wait before using the shower.
  • Billy

    can I just allow the mortar to sit uncovered for 28 days, or do I have to keep it moist?
  • N C

    do you have to wait the 28 days cure time before shower can be used if used for shower pan ? how long before grout
  • Lee-Technical Service

    Norman B, I have never heard of moisture staining a tile. The tile available today are typically hard bodied tiles and would not be affected by moisture. If it were marble, then you might get some staining but it would be from the thinset, not just the moisture. I was also wondering if maybe you are reefing to the grout joint itself. Joints can be affected by excessive moisture. If there is too much water in the grout and or if the grout is overworked. If you clean it too soon and or use too much water during clean up. All of these can cause efflorescence and mottled looking grout joints. Lots of people tile the showers within 16 hours of putting the mud bed in. There is very little water that goes into a mud bed so I would think that this is not your issue. If it is the joint and not the tile, then try using a grout cleaner to clean the joints. This should remove any excess salts and leave the tile with a move even coloration. You can also stain the joints if that doesn't work. Please let us know if this is not what you are talking about or if there is more to it.
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