What Is the Metal Sheet That Goes Under Floor Tiles?

Metal Screen Information

• A metal screen may need to be installed on top of the subfloor if the tiles are large, such as 18- or 24-inch tiles. The screen helps provide support for the tiles and the weight of people walking on the tiles. The screens should be laid in strips over the subfloor. A wire cutter is used to cut the screens near the edge of the wall. An industrial stapler should be used to attach the screen to the subfloor. A bed of mortar is then added on top of the metal screen and followed by the tiles.

Metal Lath

• A metal lath may also be placed under tile floors to provide for stronger adhesion. A layer of 15-pound roofing felt is first attached to the wooden subfloor with staples and a staple gun. The metal lath is then installed on top of the roofing felt and subfloor with corrosion resistant nails. The nails are hammered into the lath every six inches and must catch three strands of the wire mesh with each nail. The mortar bed is typically 3/4 inch in thickness and wooden floating strips can be used as a guide. The mortar is spread evenly over the lath and is compacted so the mortar presses into the lath.

Radiation Shielding

• Some buildings and geographic areas may require the installation of radiation shielding. The metal radiation shielding sheets are laid on top of concrete floors. Joints of the metal sheets should overlap by one inch. A coat of varnish over the sheets prevents a chemical interaction between the concrete floors and the metal sheets from occurring. A 1/4-inch-thick plywood subfloor is then added on top of the sheets. Tiles are then installed on top of the subfloor.

Considerations

• The type of metal product that is placed under tile floors depends on whether the tile needs additional support or better adhesion. Building codes may also dictate which type of metal product is required. In many applications, backer board can be used to install tile floors. Some tile floors may be installed without the use of a metal sheet or backer board at all if the surface is level and the tile is not heavy.