Bostik D-40 DuraFlex is a high-performance, multi-purpose latex-modified thinset mortar designed for both interior and exterior tile installations. Formulated as part of the Hydroment® PM Series, D-40 delivers strong bond strength, excellent workability, and reliable performance across a wide range of tile applications.

This white thinset mortar is suitable for installing ceramic, porcelain, granite, slate, marble, limestone, and dimensional stone. It can be applied over properly prepared concrete, cementitious backer board, approved waterproofing membranes, and existing well-bonded flooring surfaces—making it a dependable choice for residential and commercial projects.

Approved Substrates

• Properly prepared concrete

• Structurally sound exterior-grade plywood (interior dry areas only)

• Cementitious backer board

• Bostik D-222 DuraGuard

• Existing well-bonded vinyl, VCT, or ceramic tile

Applications

• Interior & exterior tile installations

• Floors and walls

• Residential and commercial projects