ARDEX FLEXBONE UI 740 Uncoupling Waterproof Crack Isolating Membrane, 215 Sq Ft Roll, 1/8" Thick, Load Bearing Floor Underlayment for Ceramic, Porcelain Tiles in Heavy Stress Areas

Product Features:

• Roll measures 1/8 inch (3 mm) thick, making it suitable for large residential and commercial tile flooring projects.
• The ARDEX FLEXBONE UI 740 underlayment membrane, made in Germany, designed for interior residential and commercial tile flooring installations requiring a high load-bearing uncoupling solution.
• Effective uncoupling action protects surfaces, tiles, and grout joints from cracking or buckling caused by natural substrate movement, moisture exposure, and temperature shifts within the subfloor.
• The unique bone-shaped stud pattern fills with thin-set mortar in one pass, and its GripLock® Technology creates an extremely strong mortar-to-membrane bond, ensuring strong tile adhesion and long-term performance.
• The stud structure distributes loads evenly, supporting tile surfaces while absorbing lateral shear movement to improve flexibility and extend tile and grout joint longevity.
• Ventilation channels in the FLEXBONE pattern compensate for vapor, allowing vapor pressure equalization beneath the tile assembly.
• The high performance felt backing supports vapor pressure equalization, helping manage moisture vapor transmission over concrete and wood subfloors, including basement installations.
• It also features waterproofing capabilities, when installed in accordance with manufacturer guidelines and proper seam treatment.
• Take advantage of the FLEXBONE UI 740’s Extra Heavy load bearing rating to protect tile installations in high-stress residential and commercial areas, including shops, restaurants, kitchens, hallways, gyms, offices, foyers, hotels, hospitals, food courts, and other high-traffic environments.
  

Product Description:

The ARDEX UI 740 FLEXBONE is a high load-bearing uncoupling and crack isolation membrane designed for safe and effective tile flooring installation over interior substrates. Installed over the prepared subfloor, it helps protect tile and stone finishes from lateral movement, substrate shifts, and existing cracks that can lead to tile damage or grout failure. The membrane is designed to be permanently bonded to the substrate using polymer-modified thin-set mortar, creating a strong, integrated underlayment for ceramic, porcelain, quarry, and natural stone tile installations.

The membrane features a distinct bone-shaped stud pattern with ARDEX GripLock® Technology that readily accepts thin-set mortar. As the mortar cures, the undercut geometry of each stud allows the mortar to mechanically lock in place, improving mortar adhesion and mechanical bond strength between the tile assembly and the uncoupling membrane. The stud structure distributes heavy loads, supports tile surfaces, absorbs lateral shear movement, and improves flexibility, helping extend tile and grout joint longevity in residential and commercial flooring applications. This durable waterproof uncoupling membrane reduces stress transfer from the substrate, helping minimize cracking and surface failures over time while reducing installation time compared to traditional underlayment systems, with added waterproofing functionality.

ARDEX UI 740 includes a felt backing with integrated ventilation channels that allow vapor pressure equalization, which is a critical factor for installations over wood and concrete substrates and in basement renovation applications where moisture vapor transmission may be present. Vapor pressure equalization helps reduce the risk of moisture buildup beneath the tile assembly and supports long-term floor performance.

ARDEX UI 740 works with a wide variety of surfaces and floor coverings, including ceramic tile, porcelain tiles, cement tiles, marble tiles, natural stone tiles, granite, existing tile, cracked but sound surfaces, painted floors, and mixed substrates, when installed in accordance with manufacturer guidelines. Suitable for residential and commercial applications, including bathrooms, kitchens, living areas, hallways, bedrooms, basements, offices, retail spaces, hotel rooms, showrooms, and renovation flooring projects.

Made in Germany, ARDEX UI740 FLEXBONE delivers reliable uncoupling performance, crack isolation, and moisture vapor management for modern tile flooring systems. Designed for high-traffic and heavy-load environments such as kitchens, hallways, living areas, basements, foyers, offices, retail spaces, and commercial settings, this uncoupling membrane provides long-term durability and helps prevent substrate-related damage under demanding conditions. Engineered for superior strength and suitable for home improvement professional projects.