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Questionable/Unsuitable Substrates

UNSUITABLE SUBSTRATES

QUESTIONABLE SUBSTRATES

Unsuitable substrates are substrate types that are not suit able to receive direct bond applications of ceramic tile and stone under any circumstances. The following are examples of unsuitable substrate types:

Questionable substrates are substrate types that when prop erly designed and prepared can receive direct bond applica tions of ceramic tile and stone. Some questionable substrates conform to specific ceramic tile and stone industry installation methodology when applicable requirements are followed. In addition, the use of specific installation materials designed for unique applications can result in a successful installation. Consult ceramic tile and stone installation manufacturers for their recommendations. The following are examples of ques tionable substrate types:

• Masonite • All grades of luan plywood • Any untreated polystyrene insulation boards without tileable surface coatings • Extruded polystyrene insulation board • Particle board • Paneling • Stripwood floors • Hardwood floors • Grease saturated concrete • Contaminated concrete • Cushion backed vinyl flooring • Paper and glass mat exte rior gypsum sheathing

• Pressure treated plywood • Fire-resistant plywood • Chemically treated ply wood • Felt paper • Scribing felt • Substrates that exceed recommended deflection under design loads • Curing compound treated concrete* • Form release treated con crete or masonry surfaces*

• Cutback or other adhe sives • Paint • Metal • Plastic laminates • Epoxy coatings • Seamless flooring • Non-cushioned vinyl flooring • Vinyl tile • Chemically treated con crete • Chemically hardened concrete

• Pre-cast concrete • Post-tensioned concrete

• Grease-coated concrete • Light-weight concrete • Cork • CDX plywood • Gypsum concrete • Gypsum plaster • Poured-gypsum underlayment • Tileable access panels • Cracked concrete

* Mechanical abrasion (e.g. shot blasting, high pressure wa ter blast, sand blasting, etc.) is required to bring these sub strate types into conformance with industry standards. See page 58. * Certain unsuitable substrate types can receive ceramic tile and stone installations when installed with a non-bonded thick-bed mortar floor assembly or a cleavage membrane/ lath and plaster wall assembly. Consult tile and stone in stallation manufacturers for their recommendations.

Certain questionable substrate types can receive ceramic tile and stone installations when installed with a non-bonded thick-bed mortar floor assembly or a cleavage membrane/lath and plaster wall assembly. Consult ceramic tile and stone in stallation manufacturers for their recommendations.

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NTCA Reference Manual | 2024 / 2025

Chapter 2 | Substrates