How to Make a Wet Bed to Level an Uneven Floor

Sweep the floor clean of any loose dirt or debris. Mop the surface using a pH-neutral cleanser and a rope mop. Rinse the floor after mopping with clean water.

Cover the floor with a layer of asphalt mastic spread in place with a trowel. Place a layer of roofing felt over the mastic. The mastic holds the felt in place. Place the felt’s first row so that the edges overlap the wall’s base by 4 inches. Cut the felt’s end with a utility knife fitting it in place. Make sure that the felt’s ends rise 4 inches up the walls’ base. Place additional felt paper rows on the floor overlapping the edges of each 4 inches over the previous row’s edge. Place the final row so that the edge also rises up the wall. Cut the felt lengthwise along the wall at the 4-inch mark and discard the excess paper.

Place a layer of metal lath over the roofing felt. Overlap the lath pieces’ edges where they meet by 2 inches. Cut the lath with a pair of tin snips when necessary for fitting. Staple the lath in place through the felt into the subfloor. Place a staple every 6 inches across the entire surface. If the floor is concrete, use metal ties connecting the lath’s overlapping edges instead of stapling it into position. Place a tie every 6 inches along the overlapping seams. The tied lath’s size and weight prevents its moving as you place the wet bed.

Make the mortar for use in the wet bed by mixing 4 parts sand with 1 part Portland cement in a wheelbarrow. Mix the two materials thoroughly together with a garden hoe, and then a latex additive to the mortar mix, using it instead of water for strength in the final bed. Mix the additive into the sand and cement until you have a wet concrete that you can shape with your hand.

Spread the mortar over the floor with a spade. Push the mortar firmly against the floor surface with a trowel through the metal lath forming a mortar layer on the floor’s surface. Lay a bed that’s about one-quarter inch thick.

Smooth the bed with the trowel as you go along. Placing a carpenter’s level on the wet bed surface as you’re smoothing it determines high or low points in the mortar. Scrape away high points from the mortar with the trowel’s edge and add mortar where needed filling in any voids. Allow the bed to cure for seven to 10 days before using the surface.