What Is the Cause of a Tile Floor in a Kitchen Buckling?

No Perimeter Space for the Underlayment

• All tile installations require sufficient room to accommodate movement over time due to the seasonal expansion and contraction of a home. The underlayment needs to be left at least a 1/4-inch shy of all perimeter areas where it ends against a wall to allow for expansion during the summer. Otherwise, the underlayment has nowhere to go, and the pressure from the board butting up against the wall causes buckling.

Insufficient Space on Tile Perimeter

• The underlayment layer is not the only part of the tile installation that needs room to breathe. The installation of the tile itself is just as important, and the reason baseboards are installed on top of ceramic tile is to hide the void left behind along the perimeters to accommodate for movement. If there is insufficient room, the tiles will press against the wall and cause buckling, just as with underlayment installed right up against the wall.

Grout Instead of Caulk

• A common mistake that many do-it-yourselfers make is to grout the joint along the wall where the underlayment and tile terminate against a perimeter, thinking that all voids need to be filled with grout. This couldn’t be further from the truth as the entire installation surface needs that space for seasonal movement. Caulking can be used instead, if you are worried about leaving behind a void, because only caulking can cushion the tile perimeter without building up pressure.

Underlayment Installation Issues

• Installing underlayment cement boards back to back without any breathing space between them is also a sure way to create floor buckling at some point down the road. The manufacturers' recommendations range from 1/8-inch to 1/4-inch between each board, depending on if you are working with mesh concrete boards or fiber boards. This extra space accommodates movement just as much as the perimeter opening does along the walls.