Spacers for All Tiles
Spacers are used to help keep grout joints in straight, even rows between tiles. While it may be tempting to remove the spacers to butt the tiles up against one another, this can cause other design problems. Tiles are rarely perfectly straight and square. The high temperatures used to produce some porcelain tiles leave them slightly warped, while machined tiles, including natural stone, can vary in size by as much as a 1/16 inch. Spacers are designed to even out these size discrepancies and help keep the rows of tile straight. By using spacers on the backsplash, even small ones, you help to create a more even design.
Spacers and Wall Tile Applications
If you choose to use a grout joint between tiles, use spacers to help keep this joint even and straight. While an experienced installer may be able to lay out a floor without use of spacers, creating an open joint simply by sight, this becomes more problematic on the walls. Gravity pulls on the tiles while the mortar is still wet, which may cause the tiles to slide slightly. This is why tiles are laid from the bottom up and supported by the counter or a temporary ledge while drying. Spacers are held in place by the pressure of the tiles surrounding them. They in turn help hold the tiles in place on the wall while the mortar dries, producing an even installation.
Spacers and Handmade Tiles
Because the backsplash is decorative as well as functional, it's common to use decorative tiles that have been handmade. Handmade tiles may be straight and square or they may be convex, concave, have waves through the body or wavy and uneven edges. Handmade tiles installed on the backsplash will require a wider grout joint and therefore wider spacers to help even out these differences. Failure to use spacers when installing these tiles on the backsplash will lead to uneven rows of tile or rows that jog back and forth with the tiles.
Remember that the backsplash is functional as well as decorative. Straight, even grout joints will do more than simply keep tile rows straight, they will help protect the wall from moisture damage.
Spaces between the tiles must be filled with grout. No matter how closely you fit the tiles together, there will still be a small gap that can let moisture through. Leaving wide, straight, even grout joints makes it easier for the grout to fill the gap between the tiles, rendering the backsplash waterproof. This will help protect the installation for years to come.