You'll need 1.5 feet of lap length if you're using 8 mm diarebar. Lapping should be avoided if possible in the center of the slab panel. The reason being that any lap marks here will usually show up when stained or finished, especially if it's a dark color. You can avoid this by making sure that the last inch-and-a-half to two inches of your slab panel is flat. If you do have to lap some pieces of wood, use a belt sander with a fine-tooth disk to smooth out the edges before finishing the slab panel. This will help create a flat surface when applied over existing subflooring. 8 mm diarebars are commonly used in hardwood flooring because they resist checking and allow for easy installation. The main drawback to this size diarobber is its cost; you'll spend more per square foot installing 8 mm diarebar flooring than you would with 7 mm or 7 1/4 mm diarebar flooring. Most homes were built with 6 mm thick floors. However, as homes become more energy efficient, there's a growing demand for thinner floors. 6 mm thick floors are now considered old-fashioned and block heat flow which can lead to heating and cooling costs increase during winter months and reduced comfort levels in summer.