Sidewalk Expansion Joint Specs

Material

• Materials used for expansion joints must be tolerable to extreme weather and temperature conditions. Expansion joints must endure scalding heat without becoming soft and shapeless, and endure freezing temperatures without becoming brittle. Common expansion joint materials are cork composition, sponge rubber, fiber or plastic. Expansion joint material is available in premolded sizes or you can cut it to your own preferred size.

Size and Thickness

• Size and thickness of your expansion joints depend upon the thickness of your sidewalk's concrete. All sidewalks should be at least 4 inches thick and 5 to 6 inches thick at driveways, with a 4-inch base of gravel or firm dirt underneath. Expansion joints must cover the entire thickness of the concrete and extend from end to end, when in place. There may be a ¼-inch space left at each end, but not more. This is typical when rounding the edges of your concrete. Expansion joints should be at least ¼ inch but ideally ½ inch thick in between each slab or fixed structure. The expansion joint may be placed a little below the top surface of the sidewalk if you are rounding the edge or giving a sharp edge detail to the concrete. The expansion joint should never extend above the top of the sidewalk.

Spacing

• In considering the overall length of your sidewalk, the expansion joints should be placed every 20 to 50 feet; but, according to Concrete Construction Magazine, expansion joints are not needed if contraction joints are placed every 5 feet along the sidewalk. Contraction joints are lines sawed into the concrete, approximately 1 inch deep across the entire width of the sidewalk. If your sidewalk is a long path you will want to use expansion joints with contraction joints to avoid any possible buckling or cracking.