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SikaTile®-350 Flex Set Superior Grade Polymer Modified Thin Set Mortar

SikaTile®-350 Flex Set is a superior grade, polymer-modified, Portland cement, flexible, multi-purpose thin set mortar with exceptional features offering flexibility, higher bond strengths, extended adjustability and open times.  It can be used for both interior and exterior installations of tile in most residential and commercial floor and wall applications. This mortar contains a high blend of dry polymers, resulting in excellent adhesion to the substrate and tile. SikaTile®-350 Flex Set, features innovative Dustless Technology producing approximately 80% less dust than ordinary thin sets and is designed to promote cleaner working conditions and reduce mess. It uses less water and is creamier and easy to spread.


SikaTile®-350 Flex Set provides flexible, high strength for flat, even installations and is suitable for bonding the following types of tile and stone:

  • Brick and thin brick
  • Cement-based precast terrazzo
  • Impervious porcelain and glass tile
  • Natural stone tile
  • Vitreous, semi-vitreous or non-vitreous tile:
    • Ceramic, mosaic, quarry, cement body tile

SikaTile®-350 Flex Set can be installed in most interior and exterior residential and commercial installations on floors and walls on the following recommended substrates:

  • Brick Masonry
  • Cement Backer Board1
  • Cement Mortar Beds
  • Cement Plaster
  • Cement Terrazzo
  • Ceramic Tile and Stone
  • Concrete
  • Concrete Masonry
  • Exterior Grade Plywood2
  • Gypsum Wallboard2
  • SikaLevel®SikaTile® Membranes
  • Approved SikaLastic® Under Tile Waterproofing


  • Ideal for Exterior Vertical Installations
  • For Glass, Porcelain, Ceramic Tile and Natural Stone
  • Adheres to Non-Absorptive Surface
  • For interior and exterior floors and walls
  • Dustless formula – provides approximately 80% less dust than ordinary mortars
  • Cleaner working conditions by minimizing dust
  • Creamier and easier to spread
  • Uses less water for consistent hydration and quicker drying
  • Longer working time
  • No-Slake – No wait. Just mix, trowel, and install
  • Mold and mildew resistant

1 Consult cement backer board manufacturer for installation recommendations and to verify acceptability for exterior use.

 Sika® is committed to environmental responsibility in both products produced and in manufacturing practices. Use of this product can contribute towards LEED® v4.1 certification:

  • Up to 2 points towards MR Credit 5, Regional Materials
  • Up to 1 point towards IEQ Credit 4.1, Low-Emitting Materials – Adhesives & Sealants


American National Standards Institute (ANSI) — ANSI A108.5, A118.15E, A118.4E and A118.11 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” or 50mm Cube Specimens) 
  • 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 EJ171 Movement Joint Guidelines. 
  • ISO 13007-2 C2EP1

Chemical Base

Portland cement, selected aggregates, water retention additives, re-dispersible polymer

Shelf Life

15 months from date of production when stored in original, sealed package

Storage Conditions

Store in undamaged, original, sealed package, in dry conditions at 73⁰ F (23⁰ C)

Slant Shear Strength

4 Week Shear Bond Strength


Test Method


Typical Results

Porcelain Tile A118.15
Section 7.2.5

> 400 psi

400 - 450

Quarry Tile to Plywood A118.11
Section 4.1.2

> 150 psi

150 - 250


ISO 13007 Classification

Classification Code

Classification Requirement


C2 (cementitious, improved adhesion) ≥ 145 psi (1 MPa) after standard aging. Heat aging, water immersion and freeze/thaw cycles Pass
E (extended open time) ≥ 72.5 psi (0.5 Mpa) after 30 minutes


P1 (normal adhesion to plywood) ≥ 72.5 psi (0.5 Mpa) Pass

Mixing Ratio

5 quarts (4.75 liters) of clean potable water per 50 lb. bag

Pot Life

60 - 90 minutes

Open Time

> 30 minutes - Passes ANSI A118.15 Section 5.3

Cure Time

Product Curing time is affected by ambient and surface temperatures and humidity. Use the following as a guideline. Allow 24-48 hours before grouting and light traffic, and 7 days before heavy or vehicular traffic. As necessary, use plywood or other load distributing protection when moving heavy equipment across tiled assembly. 

2 Interior Use Only.