Recommended Underlayment for Armstrong Alterna Tile

Recommended Underlayment Products

• Not all Armstrong Alterna applications require the use of an underlayment, as this product can install directly over many existing floor coverings. If an underlayment is needed, Armstrong recommends exterior-grade APA plywood featuring an Exposure 1 classification. Alternatives include poplar, birch, Type 1 lauan plywood, or fiber cement products specifically designed for use under vinyl or resilient flooring. Do not use particleboard, wafer board or oriented-strand board as underlayment with this flooring.

Recommended Underlayment Fasteners

• Armstrong recommends securing underlayment using ring shank nails, which you should set flush to the face of the board rather than countersink. The company does not provide a specific nailing pattern, and suggests following the nailing pattern recommendations of the underlayment manufacturer.

Acceptable Wood Subfloors

• Alterna vinyl floors can install over any wood subfloor that measures at least 1 inch thick and has at least 18 inches of air space underneath. For a standard 3/4-inch plywood subfloor, this product requires the addition of a 1/4-inch plywood or similar underlayment. You can also use a 1/4-inch plywood as underlayment over a tongue-and-groove wood floor with planks measuring 3 inches in width or less. for all other wood floors and subfloors, Armstrong recommends using a 1/2-inch underlayment. Never install this product over wood subfloors that rest directly on top of concrete without an 18-inch airspace in between.

Concrete Subfloors

• Alterna and other vinyl floors can install directly over smooth, even concrete subfloors without an additional underlayment layer if the floor is fully cured and dried. Check the surface to measure moisture and pH before installing tile. Depending on the Armstrong adhesive you use with your Alterna tile, the maximum allowable moisture level ranges from 80 to 90 percent. Concrete pH must be 9 or less for a successful installation.

Existing Floor Coverings

• Armstrong Alterna tiles can install over a single layer of firmly attached existing vinyl floor. A plywood underlayment is required if the existing floor contains multiple layers, is located below grade or consists of cushioned resilient flooring. If the floor is textured or embossed, use Armstrong cement-based underlayment to smooth the surface prior to adding new vinyl flooring. Avoid overlapping joints on existing tiles when installing over a vinyl or other resilient floor.