Natural Stone & Large Tile Premium Mortar

Product ID: TDS-309

Premium quality, polymer-modified mortar for natural stone or large format tile 15″ (38cm) or larger on one or more sides. Can be used for clay pavers or other thin or medium bed applications (up to 3/4″ thick). Non-slumping formula minimizes lippage.
Formerly named Marble, Granite & Travertine Premium Mortar

  • Supports large and heavy tile for flat, even floor installations
  • Sag and slip resistant – immediately holds wall tiles in place
  • Exceeds ANSI A118.4 and A118.11

Coverage Chart

SQUARE FOOT COVERAGE PER 50 LB BAG (SQUARE METER PER 22.68 KG)

Chart for estimating purposes. Coverage may vary based on installation practices and jobsite conditions. For more trowel sizes, please use the material calculator at CustomBuildingProducts.com or contact CUSTOM Technical Services at (800)282-8786.

Trowel Size

Min Coverage

Max Coverage

1/4" x 1/4" x 1/4" (6 x 6 x 6 mm) Square-Notch

90 sq. ft. (8.4 M²)

100 sq. ft. (9.3 M²)

1/4" x 3/8" x 1/4" (6 x 9.5 x 6 mm) Square-Notch

60 ft² (5.6 M²)

67 ft² (6.2 M²)

1/2" x 1/2" x 1/2" (13 x 13 x 13 mm) Square-Notch

IMPORTANT NOTE BELOW

42 ft² (3.9 M²)

IMPORTANT NOTE BELOW

47 ft² (4.4 M²)

3/4" × 9/16" × 3/8" (19 × 14 × 9.5 mm) U- Notch @450 angle

3/4" × 9/16" × 3/8" (19 × 14 × 9.5 mm) U- Notch @300 angle

34 ft² (3.2 M²)

42 ft² (3.9 M²)

38 ft² (3.5 M²)

47 ft² (4.4 M²)

*IMPORTANT NOTE: Custom Building Products does not recommend the use of a 1/2" x 1/2" x 1/2" (13 x 13 x 13 mm) Square-Notched trowel as the ½” spacing between each square notch has been shown to make it more difficult to bed tiles and achieve proper mortar coverage. CUSTOM recommends the use of a trowel design that promotes mortar ridge collapse such as either a deeper, slanted, U-notch, V-notch, or ridged large format trowel when applying thicker amounts of mortar to accommodate tile warpage and back pattern recesses. Applying mortar using a 3/4" × 9/16" × 3/8" (19mm × 14mm × 9.5 mm) U- Notch at a 300 angle provides better coverage between the tile and the substrate and the same coverage area as a ½” notched trowel.

Regardless of the trowel used, mortar coverage between the substrate and tile underside is required to be ≥80% for dry areas and ≥95% for wet areas and exteriors with all tile edges properly supported with mortar and in a minimum of 3/32” (2.38 mm) and a maximum of ¾” (19mm) continuous thickness. Note: Larger tiles, tiles with deep underside patterns and ungauged natural stone tiles may require larger notch sizes and may need to be flat back-troweled (formerly back buttered) or notched-back troweled to achieve proper coverage and mortar support. To meet warranty requirements, CUSTOM recommends testing to confirm adequate bonding mortar coverage.

When back troweling, consider the tile’s underside pattern and depth to estimate thickness and usage to add to your estimate. For achieving proper mortar coverage see the following video: Trowel & Error. (Also available in Spanish and Russian.) For information regarding back troweling, refer to The National Tile Contractors Association / Reference Manual & Flat Back & Notched Back - Troweling (TileTVS3 22 08)

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