Q. How large should grout joints be in tile?
A. There’s not a specific standard for the size of a grout joint, but there are some basic guidelines to consider. What is the amount of variation from tile to tile? Are the edges of the tile straight or irregular? How large is the tile? Is the sub-surface level?
A tighter grout joint will show more variation, potentially revealing mistakes in the installation. Grout also exposes the differences in the angle of the surface. When tiling over a hump, the grout joint opens up and when tiling across a depression, the top of the grout joint narrows. Larger joints do a better job of concealing such discrepancies.
Be sure to use the right grout. Joints smaller than 1/8 in. should only be grouted with unsanded grout, whereas joints 1/8 in. and larger require sanded grout. Joints larger than 3/8 in. usually need a heavily sanded grout to accommodate the large space.
Style is another factor. Lay tiles closely for a contemporary feel or space them widely for a more rustic look.