To lay tiles on an uneven floor, you will first have to create a smooth, even surface. This is traditionally done using what is called a mud bed or a wet bed. It uses a mixture of sand and cement to create a smooth surface that is as hard as concrete, but not quite as strong. This is the type of floor that is underneath all tile shower floors. The items you will need for this project is as follows:

  • Roofing Felt
  • Metal lathe
  • Galvanized roofing nails
  • Sand
  • Cement
  • Water
  • Hoe
  • Shove
  • Wheelbarrow
  • Flat trowel
  • Lattice strips
  • Straight edges
  • Level

Determine requirements and obtain materials

Measure the room and examine the floor. If the surface is concrete or old tile, then you will not need to follow Section 2. If it is a wood floor, Section 2 is required.

Obtain enough roofing felt and metal lathe to cover the floor if Section 2 is required,. Both can overlap slightly, so an exact quantity isn’t required. You will need enough roofing nails for one nail every 4-6 inches.

Divide the square footage of the room by 3 and use that number as the cubic footage of sand required. Get one back of Portland cement for each 8 cubic feet of sand.

Prepare Wood Subfloor

Roll out the roofing felt and cover the entire floor. Let the felt sheets overlap each other slightly. Lay the metal lathe over the felt and nail down with roofing nails. Pull the lathe tight as you place each nail. You don’t want the lathe to have any bounce. The lathe sheets can overlap slightly or have slight gaps between them.

Install the Mud Bed

Mix the cement with dry sand in the wheelbarrow. This should be a large commercial wheelbarrow approximately 5 cubic feet in size. Fill the wheelbarrow almost full with sand leaving enough room for half a bag of portland cement and room to mix. Add half of a bag of cement and mix with the hoe until there is not unmixed sand or cement visible in the wheelbarrow. You can do the mixing with just a flat-bladed shovel, but a large hoe makes the job much easier.

Add water to the mixture a little at a time and mix it thoroughly. Start off with about a gallon of water. Continue mixing and slowly adding water until your mixture feels like wet sand. It should just stick together good if you clench some in your fist. The mixture shouldn’t be soggy or drip water when you pick it up in your hand.

Use the shovel to place two lines of the mixture across the floor. One line should start at the highest point on the floor and extend parallel to one of the walls, preferably toward a door. The other line will be parallel to that one close enough that you can bridge both lines with your longest straight edge.

Press and tamp down on the mud mixture to compress it. Your starting place at the highest point on the floor should be at a depth of about an inch. Place a piece of the lattice strip on the line with the starting point. Using the level and again starting at the high point, move the level back and forth, pressing down on the lattice strip to make it level with your starting point. When complete, you should have one level line of mud, fully compressed which is level with your starting point about an inch above the highest point on the floor.

Place another strip of lattice strip on the other line. Use the straight edge to span the two lattice strips. Place your level on the straight edge and tamp down on the second strip until it is level with the first. Next using the level, make the second line of mud level in the same fashion you used on the first. At this point, you have to lines of cement that are level with each other. This will be your working level for the rest of the floor.

Fill the area between these two lines with mud, mixing more as needed. Spread the mixture fairly even and level to a height an inch or two above your lattice strips. Use the trowel to tamp it down firmly. The area between the two strips should now be full and tightly compacted, slightly higher than the lattice strip. Carefully remove the lattice strips and replace them with a shorter length of 3-4 feet.

Place the straight edge across both lattice strips starting at one end of the room. Using a sawing back and forth motion, pull the excess mud from the center so that it is flush with the lattice strips. Use the trowel to smooth back over the surface. If the trowel sinks into the mud or makes a depression, trowel more mud into that area and repeat. As you back across the room in this fashion, you should be leaving a smooth, level cement surface flush with the lattice strips.

Slide the short lengths of lattice strip back as you go, giving you a new surface to work from. Carefully, fill the void left by the lattice strip with mud and smooth with the trowel. Now as you complete each section, you are leaving a smooth, even, cement floor behind you.

Continue backing across the room using the same method until the entire room is covered and even. You now have an even surface on which to install the porcelain tile.

Laying the tile

Mark a straight line off the longest wall, two tile widths plus the width of your grout joint, preferably in a line of site from a door. This will make sure the tile looks straight even if the room is out of square. Mix thin-set according to package directions and spread it with the notched trowel between the line and the wall. Place the tile against the line and work toward the wall. Gently twist or tap the tiles into the thin-set to ensure a good bond. Make any needed cuts against the wall with the tile saw. Porcelain tile is harder and usually larger than ceramic tile, so a tile saw is preferred rather than a traditional tile cutter.

Continue working across the floor in this fashion, spreading and tiling a couple of feet at a time. Make cuts as you go with the tile cutter. Allow the floor to set 24 hours when complete.

Mix grout according to package directions. Spread using the grout float, forcing grout into all joints and pulling the excess off with the edge of the float like a squeegee. Wash grout off of the surface of the tile with a damp sponge while smoothing the joints at the same time. Allow grout to dry to a haze and then wash again with clean water. Allow to dry, then buff with a clean dry towel if necessary.