Installing wood laminate flooring over a concrete slab provides stability for the new floor. Concrete slabs are the most popular subfloor for a new laminate floor. There are preparatory steps you must take before installing the floor, to ensure the floor will not creak or crack after use. Before installation, you must also treat the concrete to make sure moisture does not seep up into the laminate flooring.
Leave the laminate flooring in the room where you plan to install it for 48 hours. This gives the flooring a chance to become acclimatised to the atmosphere in the room, which may include some swelling of the wood.
Sweep the floor thoroughly with a broom. Lay the 6 foot straight edge down on the floor, starting in the corner farthest from the door. Slowly move the straight edge across the length of the floor, then down the width of the room. Note any low spots or rises in the flooring.
Mix your concrete levelling compound in a five-gallon bucket, according to package directions. In general, you add water until it forms a thick paste. Apply the levelling compound to any low spots with a putty knife. Use the knife to smooth the surface of the compound. Let it dry overnight.
Use the surface grinder to grind down any high spots in the flooring. You can rent a surface grinder from your local home improvement store. Operating instructions will vary with the grinder you select, so be sure to read the manual completely before you begin using the machine. Sweep the floor again when you are done.
Pour concrete sealer into a paint tray. Starting in the corner farthest from the room's entrance, begin applying a thin layer to the concrete slab with the roller brush. Apply a layer to the entire floor. Allow it to dry according the package instructions. The concrete sealer will keep moisture from warping the flooring once you install it.
Lay 1/4-inch spacers against the far wall. The spacers provide the necessary expansion room for the flooring, since it will swell and shrink as the humidity in the room changes.
Lay a full length plank against the spacers, at the top of the room. Lay another plank at the end of the first. Insert the tongue into the groove end of the first plank, listening for a click that means the two planks have joined. Continue joining the first row of planks until you have a full row.
Select a 2/3 plank to begin the next row, and then a 1/3 plank to begin the third row. The fourth row should start with another full length plank. Always join the next plank to the preceding ones by clicking the tongue-and-grooves together. Use your soft headed mallet to gently tap any planks into place that you are having trouble joining. Repeat until the entire floor is complete.
Install your trim or moulding around the edge of the room. The installation instructions will vary, depending on the moulding you selected.
Most laminate floors come with the underlay attached, but if yours does not, simply lay the underlay before you set the spacers. The underlay should come up the wall 2 inches.