Mortar under the Shower Base

When installing a new tub or shower you may find your self in need of leveling the roughed in area. Most hardware or home improvement centers sell different types of mortar that can be used to level the tub/shower base fairly simply.

What Type of Mortar to Use

It will save you a lot of time and hassle if you use a pre-mixed thin-set mortar. The thin-set mortar will allow you to level the uneven section to some degree and it is relatively inexpensive.

If you were to use a brick mortar you may later be faced with a mold or mildew build up on the surface of the mortar. Another type to use may be the Mira X Plan to level the underbelly of the base.

How to Apply

Now you’re ready to apply the mortar. If you did not purchase the premixed mortar, follow the manufactures instructions on the package.

First use a smooth edge trowel to spread and then use the notched trowel (raking it over the surface to create and adhesive gripping surface).

Make sure you push the mortar into all the groves in the surface for added protection. There may be some areas where a build up is necessary. To do this you may have to apply more than once allowing some drying time in between applications. You can use a level to check the surface once it has dried some then correct any missed areas.

The Use of Cement Board

You may choose to use a piece of cement board to help ensure a level surface. This is accomplished by cutting the cement board to the shape of the rough surface, then laying the mortar (while still wet- DO NOT let the mortar dry) in a level pattern.

Once you have done this then you can place the board using shims if you still have problem areas. The shims can be removed after the mortar has dried. Secure the board into the mortar with 2 1/2 “deck screws. The screws will need to go into the floor joists for support.

Now You’re Ready

You have just created a secure, sturdy and level area for your shower base. Now you can lower it in and finish your install, creating a relaxing and functional home improvement.

See Also: Installing Shower Pans