What is the rule about expansion joints?
Answer Expansion joints and control joints can’t help with frost heaving, but they are necessary to mitigate other kinds of cracking. Expansion joints, which go all the way through the slab, allow minor movement of the concrete something you can’t prevent. These joints essentially break up a larger slab into smaller, less vulnerable pieces. Control joints, or relief joints, run only an inch deep and provide a channel for the harmless cracks that happen as the concrete cures and shrinks. On sidewalks, both these joints run across the width of the walkway. Expansion joints shouldn’t be more than 24 feet apart. Control joints should be spaced the same distance as the width of the sidewalk. On patio slabs, the joints are often divided into a grid, with the control joints about 8 feet apart and expansion joints no more than 24 feet apart. There should also be expansion joints wherever the patio butts the foundation or forms an inside corner. It’s possible for a masonry contractor with a spe
