Tile & Stone Installation

Sill and Wall Mud (821)

SGM Sill and Wall Mud (821) is a mud / light-weight plaster substrate, factory blended, and consisting of Portland Cement, sand, and lightweight fillers. This product is designed for use as a lightweight plaster substrate bedding (brown coat), which does not place an additional load on structural members. Sill and Wall Mud 821 eliminates costly job-site mixing of sand and cement mixes.

Product Details


SGM Sill and Wall Mud 821 may be used over the following substrates without metal lath:

  • Portland cement plaster;
  • Gypsum wallboard;
  • Concrete block;
  • Brick; or
  • Clay tile.

Metal lath is required when going over the following:

  • Masonite;
  • Wood;
  • Metal; or
  • Plastic products.

All surfaces must be clean, dry, and free of wax, grease, scaly paint, and all other foreign matter. Hence, any further cleaning shall be done using SGM Safe Clean Crystals; refer to Safe Clean Crystalslabel directions. Remove all liquid curing agents. All materials and areas to be tiled should remain above 40°F (forty degrees Fahrenheit) 24-hours prior and 72-hours after installation.


Add sufficient cool, clean water to dry mix, approximately 1.5 gallons per 50 lbs. of Sill and Wall Mud. Mix until mortar becomes trowable; let material slake five (5) minutes, then re-mix. Apply Sill and Wall Mud to the surface using sufficient pressure to work mortar to form a good mechanical bond. Float Sill and Wall Mud to desired thickness (maximum of ? inch). Cut in material approximately every two (2) feet to four (4) feet both vertical and horizontal and allow for cuts to fall out on tile joints.


The minimum cure is reached in 24 hours. Tiles may be set the same day Sill and Wall Mud is applied.


Twenty-eight (28) to thirty (30) square feet at ½ inch (13 mm) thickness per 50 lbs. bag.


Up to one (1) year from date of manufacture in an unopened container.


Product is alkaline on contact with water. Use paddle for mixing to avoid splashing into eyes or contact with skin. During mixing or application avoid contact with eyes. In case of such contact, flood eyes repeatedly with water and CALL A PHYSICIAN. Wash thoroughly after handling and before smoking or eating. Do not take internally. CONTAINS FREE SILICA — DO NOT BREATHE DUST. Prolonged exposure to dust may cause delayed lung disease (Silicosis).

WARNING: This product may expose you to chemicals, including silica, which the State of California recognizes as a cause of cancer. For more information, visit the Proposition 65 Warnings Website (www.P65Warnings.ca.gov). Use NIOSH approved masks at all times to handle silica dust. KEEP OUT OF REACH OF CHILDREN.


In case of skin contact, wash thoroughly with plenty of warm soapy water. For eye contact, flush with plenty of water for 15 minutes and get medical attention immediately. If you experience difficulty breathing, leave the area to obtain fresh air. If continued difficulty is experienced, get medical attention immediately. If swallowed, do not induce vomiting, get medical attention immediately. KEEP OUT OF REACH OF CHILDREN.


None required.

SGM, Inc. warrants this product will perform in accordance with its intended use for a period of one (1) year from the date of manufacture. Any claim for defective product must be submitted in writing to SGM, Inc., and samples of defect must be provided. SGM, Inc.’s sole obligation will be to replace any product determined to be defective by SGM Inc. EXCEPT AS PROVIDED HEREIN, SGM, INC. MAKES NO OTHER REPRESENTATION OR WARRANTY OF ANY KIND, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR PARTICULAR PURPOSE. IN NO EVENT SHALL SGM, INC. BE LIABLE FOR DAMAGES OF ANY KIND OR NATURE, WHETHER ARISING BY CONTRACT, TORT OR OTHERWISE. SGM, INC.’S SOLE OBLIGATION WILL BE TO REPLACE ANY PRODUCT DETERMINED BY SGM, INC. TO BE DEFECTIVE.