Checking the unevenness of the floor

When working on flooring, e.g.. pouring out self-leveling masses, or cement screeds, but also when laying the floor panels it is important to determine the unevenness of the subfloor or the ceiling. Any deviation, first of all, concavities can be easily determined by applying a long one, a simple wooden or better metal patch. It should be applied in different places on the ground and in different directions. By observing the size of the clearances between the patch and the ground, we mark the most concave or convex places.