Light shotblasting is generally the most efficient way to abrade the subfloor surface.


Each part of the electrically conductive epoxy adhesive must be mixed independently before the two parts are thoroughly blended together.
Many high-tech customers’ electronics assembly plants, computer stores, and office buildings with telephone centers and computer rooms need flooring that reduces electrostatic discharge (ESD). Static is generated by simple movements, such as walking across a floor or pulling tape from a dispenser. Static charges build up on a body and then discharge the familiar "zap" of a static shock. Even a small charge, measuring just a few hundred volts, can damage miniaturized circuits in computers, cellular telephones, and other devices, causing them to function erratically or fail completely.

The first line of defense in preventing this damage is to install static protective permanent flooring, and require employees to wear conductive heel grounding-straps or footwear. This system minimizes static build-up on personnel, and carries any charges to electrical ground through the floor.

Installing ESD tile is similar to installing vinyl composition tile (VCT). However, the differences are important enough that they may affect the tile's electrical and physical performance.

Apply the tile in sections that are laid out to equal the coverage area of one-gallon unit of adhesive. Drop each tile into place, pressing evenly and firmly.
  • Determine the moisture level in the concrete subfloor. Most ESD tile is solid vinyl. It contains much less filler and doesn't "breathe" like common VCT. Any moisture in the subfloor will be trapped, and may cause the tile to bubble, buckle or loosen. Consequently, the moisture vapor transmission rate (MVTR), as measured by the industry-standard test, must not exceed 3 pounds moisture-vapor pressure per 1,000 square feet per 24 hours. If the MVTR exceeds this level, allow the subfloor to dry longer or apply a moisture-barrier product.
  • Abrade the subfloor surface. ESD tile requires a special electrically conductive adhesive. For the best bonding results, roughen the concrete surface. Aim for a texture similar to 100-grit sandpaper, which is typically done by light shotblasting.
  • Establish the path to electrical ground. Typically, you will install one ground point for every 1,000 square feet of floor space, with a minimum of three in a room. Locate the ground points where the building electrical ground is readily accessible, such as below an electrical wall outlet. The ground connections are made with copper foil strips, each 18-inches long. Stick two-thirds of the strip to the subfloor, and extend the rest up the wall, so that a couple of inches stand above the cove base. An electrician will jumper this stub directly to the outlet ground. These strips not only provide the path to ground, but also give auditors a handy place to check the floor's electrical performance as time goes on.
  • Mix the two-part adhesive thoroughly. The special electrically conductive adhesive is a two-part reactive epoxy. The two parts must be mixed thoroughly, first separately and then combined, until the blend is homogenous. Failure to mix the two parts thoroughly will hamper the curing.
  • Use the trowel notch size indicated on the adhesive package. The notch size, along with the installer's technique, the floor's porosity, and other factors, will affect the spread rate. Spread the adhesive directly over the ground strips adhered to the subfloor.
  • Work within the adhesive's time "window," beginning after spreading the water to flash off, but not so long that the adhesive starts to "skin over." The adhesive must be wet when the tiles are laid and later rolled.

    After each section has set for 20-30 minutes, use a 150-pound roller to roll the tile, first in one direction, then again in a perpendicular direction.
    A good rule of thumb is to work in sections sized to roughly match the spread rate of one unit of adhesive. For example, for a gallon of adhesive with a 135-square-foot spread rate, lay out a pattern 3-feet-wide by 45-feet-long. This checks whether you are spreading adhesive at the correct rate, and also helps you stay within the working time window.

    With reactive-epoxy adhesive, it's important to finish laying tiles over any exposed adhesive. If the adhesive cures and you later apply a fresh coat, the hardened trowel ridges of the previous coat will cause any tiles laid over the same area to lie unevenly and adhere poorly.

    Drop each tile into place and press evenly and firmly. If any adhesive oozes up between the tiles or onto the surface, wipe it off immediately with a soft, clean rag and warm, soapy water. If allowed to cure, the adhesive will be hard to remove. Its black color can ruin the appearance of light-colored tiles.

    Roll the finished section in two directions. After the tile has set for 20-30 minutes, roll the section twice with a 150-pound roller, first in one direction, and then in a perpendicular direction.

    Lift an installed tile periodically to check the adhesive coverage. The goal is to cover 100% of the tile back with the adhesive. When the tile back is completely black, you know the spread rate is about right, and that the rolling was done at the right time. Proper adhesive coverage affects both the bond and the floor's electrical conductivity. This quality-control step is essential to successful installation.

    If installed with reasonable care, and according to the manufacturer's instructions, the finished floor will do its job of reducing static and provide an attractive, durable surface.