Do You Need Joints in a Floating Concrete Porch?

Seasonal Movement

• Seasonal movement is best described as the movement of a material as it reacts to Mother Nature’s changes in temperature. As the weather warms up, materials swell. As the weather cools down, materials shrink. It is not the shrinking that affects flooring installations, but rather the swelling. If joints and space are not provided, buckling will occur, which forces the floor elements to pop up and away.

Swelling

• Not all floating floor installations are affected by swelling, as composites and vinyl products will not be affected by water. Wood, on the other hand, naturally swells when it comes into contact with water, whether in the form of rain, condensation from the concrete slab below or simple humidity in the air. If no room is provided for the swelling of the wood, buckling will occur.

Termination Joints

• Any area where the floating floor terminates needs to have at least a quarter-inch of space to allow for movement across the entire floor. This is especially true of tongue-and-groove installations on top of the slab. Because there is no individual spacing between each plank on the deck, the only place the floor has room to expand due to the various elements is along the outer edges where the installation terminates. If you cut the deck tight to the wall of the house, for example, buckling will occur.

Deck Joints

• If you have ever walked on a wood deck, you will notice that there is spacing between each individual deck plank. This is because of the swelling that occurs when wood is wet. However, composite materials also have individual deck spacing requirements for installation over concrete porches. The exact spacing will depend on the manufacturer’s recommendations, but as a general rule, there should always be at least 1/8 inch spacing for non-tongue-and-groove installations.