With frequent use, wooden gates are vulnerable to the effects of gravity. If the gate is in good shape but rubs or the latch is not aligned, installing a diagonal brace can correct the problem. Wooden diagonal braces may work for a while, but moisture causes the wood to expand and contract and the gate can sag again. Anti-sag gate kits consist of a stranded steel wire brace that isn't affected by moisture. In most cases, a homeowner can install the kit and align the gate in a relatively short time using everyday do-it-yourself tools.
Close and latch the gate and align the gap between the gate post and the edge of the gate at the latch side. To do this, lift up on the gate and install a wooden shim into the gap near the upper portion by hand until the gap is uniform from top to bottom. Work from the side of the gate that has the upper and lower horizontal rails.
Set up a cordless drill with a screw-tip attachment. Position one of the provided corner brackets on the face of the upper rail at the hinge side. Align the 90-degree edges at the upper edge and inner end of the rail that's closest to the gate post where the hinges attach. Attach the bracket with a 1 1/2-inch deck screw at each machined hole on the flat portions of the bracket.
Position the other corner bracket on the face of the lower rail at the outer corner on the latch side of the gate with the edges aligned at the lower edge and outer end. Attach it to the rail with screws at the machined holes.
Insert the hook at the end of the provided turnbuckle into the larger hole in the top bracket at the hinge side. Insert one end of the steel cable through the eye at the other end of the turnbuckle, and pull the end through four inches. Attach a cable clamp over the cables where they fit alongside each other, and tighten the clamp with an open-end wrench.
Loop the other end of the cable through the larger hole in the lower bracket and pull the cable tight. Install the other cable clamp around the two strands of cable four inches from the lower bracket.
Insert the tip of the screwdriver into the slot on the turnbuckle and and push up on the handle to rotate and tighten the turnbuckle. Reinsert the tip at the lower side of the slot and push up on the handle. Tighten the turnbuckle until the vertical gap at the latch side remains uniform without the wooden shim. Cut off the excess ends of the cable 1 inch from each clamp, using wire cutters.