KERDI-FLEX is a waterproofing strip with a built-in elastomeric center section that accommodates movement at structural joints, expansion joints, and transitions between different substrates. Standard KERDI membrane and KERDI-BAND are rigid — they'll bridge a seam, but they can't handle substrates that move independently. KERDI-FLEX can.

The 10" width gives you 5" of bonding area on each side of the movement joint, with the flexible center section spanning the gap. It's the correct solution anywhere two structural elements meet but might move differently — concrete-to-concrete construction joints, wood-to-concrete transitions, or any location where the architect specified an expansion joint.

When to use KERDI-FLEX vs. KERDI-BAND

• KERDI-BAND (rigid): For sealing seams between sheets of the SAME substrate that move together — KERDI-to-KERDI overlaps, KERDI-BOARD panel joints, pipe penetrations
• KERDI-FLEX (flexible): For joints between substrates that move INDEPENDENTLY — construction joints in concrete, wood-to-masonry transitions, expansion joints specified in the construction documents
• Rule: If the joint has a gap, a foam backer rod, or was specified as a movement joint — use KERDI-FLEX, not KERDI-BAND

Installation

• Apply thin-set mortar to both sides of the joint (not in the joint itself)
• Center the KERDI-FLEX strip over the joint with the elastomeric section spanning the gap
• Embed the flanges into the mortar — full contact on both sides
• Do NOT fill the joint with mortar or embed the flexible center — it needs room to flex
• Overlap adjacent KERDI membrane by minimum 2" over the flanges

Critical notes

• The movement joint must continue through the tile surface — use a soft joint (caulk/sealant), NOT grout, at the tile level
• KERDI-FLEX handles movement, not structural loads — the substrates on both sides must be independently supported
• Maximum joint width: consult Schluter technical data for your specific application

Specs

• Width: 10" (25 cm)
• Center section: Elastomeric (flexible)
• Flanges: KERDI membrane material (bonds with thin-set)
• Sold by: Linear foot

Pairs with

• KERDI waterproofing membrane
• KERDI-BAND (for non-movement seams)
• Schluter SET or ALL-SET mortar