Products : JAMO : Surface Prep : Floor Mud Pre-blended Underlayment

Floor Mud Pre-blended Underlayment

FLOOR MUD produces an excellent underlayment for floor tile installations. FLOOR MUD is a factory blend of Portland cement, sand and chemical modifiers for floating shower pans and other floor areas. Meets ANSI A108.1, A108.4, A108.5 and A108.6.

  WHERE TO BUY Not all products are sold at all stores. Please call the distributor to ensure product availability.
Have a question?



FLOOR MUD is used for the forming of shower floors and curbs. It is good for interior or exterior applications and will not be affected by prolonged contact with water after it is properly cured. Designed to be mixed with water or Jamo’s STAR SET® 1000. FLOOR MUD becomes a smooth and easy-to-apply mortar bed.


TDS Documents

Technical Data Sheet


Suitable Substrates

Suitable backings, when properly prepared, are masonry concrete, WonderBoard® Backerboard (dry areas only), and cured Portland cement mortar beds.

General Surface Prep

All surfaces must be dry, structurally sound, free of any dirt or curing compounds, and not subject to temperatures below 40°F (4.5°C) or above 100° F (38° C). Additional installation procedures may be found in the TCA Handbook.

Health Precautions

May cause eye, skin or lung injury. Contains free silica. Prolonged exposure to dust may cause delayed lung disease (silicosis). May cause cancer based on animal data. Eliminate exposure to dust. Use NIOSH approved dust mask for silica dust. Contains Portland cement. If any cement or cement mixture gets into eyes, flush immediately and repeatedly with water, and consult physician promptly. Fresh mixed cement, mortar, concrete, or grout may cause skin injury. Avoid contact with skin where possible and wash exposed skin areas promptly with water. KEEP OUT OF REACH OF CHILDREN.

Limitations to the Product

FLOOR MUD must not be used directly over wood, asphalt sheeting, vinyl covered wall board, Masonite® , cement asbestos board, painted surfaces, metal, glass or plastic. Use in temperature ranges above 40° F (4.5° C). Protect from freezing for the first 72 hours.

Mixing Procedures

FLOOR MUD should be added to clean, potable water or Jamo’s STAR SET® 1000, a latex admixture in the temperature range of 50°F to 80°. Mix thoroughly with 2.75-3.25 quarts (2.6-3.7 L) water into 50 pounds (22.68 kg) of FLOOR MUD. (up to half water may be replaced with STAR SET® 1000). Let mortar stand for 15 minutes then remix before using. Mix to a damp consistency which allows the mortar be formed into a ball without crumbling. Do not add water, latex, or additional powder after slaking period.

Application of Product

Saturate clean, smooth concrete surfaces with water immediately before placing FLOOR MUD. The surface must be free from standing water. Before placing FLOOR MUD, spread a very thin continuous layer of pure Portland cement paste on the concrete surface. Immediately apply FLOOR MUD over the pure Portland cement coating. Firmly tamp and screed the FLOOR MUD. The thickness should be between 3/4" and 1-1/4" (19.1 and 31.8 mm). A minimum of 1-1/4" (31.8 mm) thickness is required for shower receptors. Shower stall areas also require a suitable waterproofing membrane and reinforcement. Consult local building codes, ordinance and trade practices.

Curing of Product

A minimum cure will be obtained in 12 – 24 hours, depending on ambient temperature. As with concrete, the strength will increase significantly with age during the first 28 days.

Cleaning of equipment

Water will remove uncured mortar from tile surface or tools.

Warranty Information

Product Warranty

Seller warrants that should this product prove to be defective material, it will replace the same or refund the purchase price of the goods. THIS WARRANTY IS IN PLACE OF ALL OTHER WARRANTS EXPRESSED OR IMPLIED. WARRANTIES OF MERCHANTABILITY AND OF FITNESS ARE HEREBY DISCLAIMED. The suitability of a product for an intended use shall be solely up to the user. Seller assumes no liability for consequential damages. Its liability shall in no event exceed the purchase price of the materials supplied by it. No person has the authority to change these items and there are no warranties except as herein stated.

© 2021 Custom Building Products. All Rights Reserved. Privacy