All concrete services need to be sealed when a timber floor is applied over the surface. Concrete has the ability to allow moisture to migrate through its structure. When this water rises to the surface even in minute amounts and it reaches the back of a solid timber floor it can cause that timber to expand. It does not matter how old the concrete is. Reticulation may play on the wall of a house and the water migrates through the concrete and affects the timber and floor failure can be catastrophic. Dishwashers may leak as may fridges or other wet areas and moisture may migrate into the concrete. Following this disaster may follow if there is no moisture barrier applied to the surface of the concrete under the timber. Sika MB primer is an ideal moisture barrier for protecting your floor and we strongly recommend the use of an MB primer under any floor.