Products : Surface Prep : Mud Bed and Patching Compounds : Fast Setting Thick Bed Mortar

Fast Setting Thick Bed Mortar

Fast Setting Thick Bed Mortar is a pre-blended sand and cement formula to prepare for the installation of ceramic tile using the thick set method. To increase strength and reduce water absorption it should be mixed with Custom’s Mortar Admix. Economical, saves time with no job-site blending of sand and cement is required. High-strength, ideal for commercial and industrial installations.

This pre-blended underlayment is specifically designed to float a mortar bed for ceramic tile. It is easy to mix and use, eliminating the need for site mixing of sand and cement. Fast Setting Thick Bed Bedding Mortar's 3:1 mix ratio provides a high-strength surface ideal for tiling commercial and industrial installations.

Available in select markets only.

  WHERE TO BUY Not all products are sold at all stores. Please call the distributor to ensure product availability.
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Key Features

  • Pre-Blended — No job-site blending required
  • Easy to mix and use


Applicable Standards

American National Standards Institute (ANSI) ANSI A108.1 of the American National Standards for the Installation of Ceramic Tile ASTM International (ASTM)

  • ASTM C109 Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in.or [50-mm] Cube Specimens)
  • ASTM C627 Standard Test Method for Evaluating Ceramic Floor Tile Installation Systems Using the Robinson-Type Floor Tester

Resilient Floor Covering Institute (RFCI) Recommended Work Practices for Removal of Resilient Floor Coverings Tile Council of North America (TCNA) TCNA Handbook for Ceramic Tile Installation, TCNA Method EJ171

Conformance to Building Codes

Installation must comply with the requirements of all applicable local, state and federal code jurisdictions.

Environmental Consideration

Custom® Building Products is committed to environmental responsibility in both products produced and in manufacturing practices. Use of this product may contribute to LEED® certification.

Suitable Substrates

  • Interior or exterior
  • Floors
  • Concrete
  • Exterior grade plywood (interior applications only)

General Surface Prep

Use impervious gloves, such as nitrile, and safety glasses when handling product.

Surfaces must be structurally sound, clean, dry and free from grease, oil, dirt, curing compounds, sealers, adhesives or any other contaminant that would prevent a good bond. Glossy or painted surfaces must be sanded, stripped and cleaned of waxes, dirt or any contaminants. Concrete must be cured 28 days and accept water penetration. Concrete must be free of efflorescence and not subject to hydrostatic pressure. Concrete slabs should have a broomed or brushed finish to enhance the bond. Plywood flooring must be structurally sound and meet all ANSI and deflection requirements. For questions about proper subfloor installation, call Technical Services. Smooth concrete surfaces, existing glazed tile, terrazzo, or polished stone should be roughened or scarified. Roughen the surface by sanding or scarifying, rinse and allow to dry. Expansion joints should never be bridged with setting material. Do not sand flooring materials containing asbestos. Ambient temperature, surfaces and materials should be maintained at a temperature above 50° F (10° C) or below 100° F (38° C) for 72 hours.

Movement Joint Placement

Expansion joints and cold joints, as described in ANSI A108.01, should never be bridged with setting material. They must be brought through the tile work and filled with an appropriate elastomeric sealant, such as Custom's® 100% Silicone. Contact Custom's® Technical Services for the proper treatment of control or saw cut joints. Refer to TCNA EJ171, F125 and F125A.

Health Precautions

This product contains Portland cement and free silica. Avoid eye contact and prolonged contact with skin. Wash thoroughly after handling. If eye contact occurs, flush with water for several minutes and consult a physician. Do not breathe dust; wear a NIOSH approved respirator. Refer to Safety Data Sheet for complete safety information.

Limitations to the Product

Do not apply directly over wood, metal, fiberglass, plastic and OSB panels lightweight concrete, gypsum underlayment, OSB, particle board, hardwood or Parquet floors.

Bonding to Concrete Surfaces

Concrete or plaster must be fully cured and must accept water penetration. Test by sprinkling water on various areas of the substrate. If water penetrates, then a good bond can be achieved; if water beads, surface contaminants are present, and loss of adhesion may occur. Contaminants should be mechanically removed before installation. Concrete must be free of efflorescence and not subject to hydrostatic pressure. Concrete slabs should have a broomed or brushed finish to enhance the bond. Smooth concrete slabs must be mechanically abraded to ensure a good bond. Use bonding mortar to adhere to concrete surfaces.

Bonding to Plywood Surfaces

Plywood floors, including those under resilient flooring, must be structurally sound and must meet all ANSI A108.01 Part 3.4 requirements. Follow TCNA F141 or F145 guidelines for the installation of the thick bed mortar over plywood sub floor. For questions about proper subfloor installation, call Custom® Building Products.

Mixing Ratios

Thoroughly mix 3 quarts (2.84 L) Mortar Admix and 50
lbs. (22.68 Kg) of Thick Bed Mortar to a semi-damp, dry pack



Application of Product

Follow ANSI A108.1 A, B or C for the installation of ceramic tile with thick bed mortar.

Drying Time

Curing time is affected by ambient and surface temperatures and humidity. Use the following as a guideline; 24 hours before grouting or light traffic.

Cleaning of equipment

Clean with water before material dries.

Handling & Storage

Store in a cool dry area.

Product Maintenance

Properly installed product requires no special maintenance.

Ordering Information


50 lbs. (22.68 Kg). bags

Coverage Chart


Approximately 5 - 6 sq. ft./50 lbs. (.46 - .55 m2/22.68 Kg) when applied with at a 1” (2..5 cm) thickness.

Chart for estimating purposes.  Coverage may vary based on installation practices and jobsite conditions.  You can also use the material calculator at or contact CUSTOM Technical Services at 800-282-8786.

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