I have had a extension built at the back of my house. It is almost complete now. I had a 6 ft. 6 in. patio door at the back of the house, and the builders left it till last to remove. This will leave my kitchen to be open plan into the extension. When they removed the door, they found that the floor was a different level. As a fix, the builders, working by hand, have put more concrete down in strips. I wanted to put a quality laminated floor down, but the strips have made the floor uneven. Would a floor leveler product be appropriate in this application?