An Expansion Joint is used when a driveway is poured to allow for expansion of the concrete and help keep the driveway from cracking. Until recently, the expansion joint was generally a 1×4 board used with wooden stakes to frame around the concrete pour areas. The construction crew nails a frame of wood and pours the concrete inside the frame to form a sidewalk or driveway. After the concrete dries, the outside boards and stakes are removed. The inside boards and stakes remain as expansion joints. Recently, true expansion joints have been replaced by control joints. A control joint is designed to control where the expanding driveway will crack. In this case, the boards used are 1×2 or shorter, and a frame is staked and nailed together. This time, when the concrete is poured, it flows under the shorter boards and is added until level with the top of the boards. Once the expansion joints in your driveway, sidewalk, or pool deck rot away, you will see concrete below where the board used to be.
A missing expansion joint can create a safety hazard for adults and small children. Rainwater can wash through the empty areas and under the slab, which can remove sand and weaken the integrity of the surface. Dirt, weeds and grass can fill in these areas, prompting herbicide use or a letter from the homeowner’s association.
There are different methods to replace expansion joints.
1. For the doityourselfer, there is a product which comes in a caulking tube which is used with a closed cell foam rod or sand below it.
2. There are companies who professionally use a multi stage self leveling product. The slab surface has to be extremely clean and dry before using either of these products, and must cure for at least 24 hours before walking or driving over it. If done improperly, when the expansion joints contract, these products can lose the grip or rip down the center.
3. You can purchase new boards and try to hammer them into the empty areas. This can be very difficult and usually the boards warp at the ends and foster an additional trip hazard.
4. A new product has been introduced which is made from extruded vinyl. To date, seven sizes are available. It is called SlabGasket, and is available at SlabGasket.com, at the local office in Park Ten, or from one of our dealers. (see dealer locater on the web site) After the old expansion joints have been removed, step and tap in SlabGasket. No curing or pressure washing is required. Snug fitting SlabGasket helps eliminate trip and fall hazards, impedes weed growth, and greatly improves the home curb appeal. It is readily available for the doityourself homeowner, or professional installation can be arranged in limited areas. Browse the web site for pricing, available sizes, installation tips, pictures and videos.