Crack-isolation membrane stretches; joints still required
An anti-fracture membrane is bonded to the concrete, and the tile is bonded to the membrane, yet the membrane stretches where it must so force from the slab is reduced before it reaches the tile. That stretch is not a movement joint. Soft joints still have to let the tilework expand and contract, and the FAQ calls it a misconception to omit them because a membrane is present. Products are trowel-applied or sheet-applied. Performance varies, and the maker's instructions control the use.
Joints stay in the tile
A frequent misconception, the FAQ says, is that these membranes let you omit expansion joints. They do not. Soft joints still have to allow the tilework to expand and contract. Handbook guidance covers placement. Sun, temperature range, moisture, concrete age, structure, and expected load all change the spacing. Felt paper used as a cheap stand-in generally fails to hold bond, does not hold up to moisture, and can grow fungus.
Coverage choices
Makers sell these products to cover shrinkage cracks, to cross control joints, or to protect a whole floor. Covering the whole floor is a different scope from treating one crack. Some makers will stand behind a full-floor use. The page says to read that maker's limit rather than assume every membrane can cross a control joint.
Source
Fetched 2026-10-11 from Tile Council crack-isolation FAQ. The sentences above follow that page. They are not a contractor promise.
Related notes
- Tile notes index
- Concrete does not have one cure time before tile
- A cleavage membrane lets the mortar bed slip
- Shower photos
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