A sleeper is a thin piece of wood which is laid on top of a concrete floor providing a surface to which a finished floor can be nailed or glued.
Why use a Sleeper?
Generally speaking, a number of types of finished floors cannot be attached directly to concrete. The most notable of these is solid wood floors which have become increasingly popular as a flooring material. A sleeper is used to provide a surface to which the finished floor can be attached to either using glue or nails.
The construction of a sleeper usually involves laying down some type of thin strip wood such as plywood. This should be done using a moisture resistant type of plywood to prevent warping or damage as a result of moisture coming up through the ground.
It is also recommended that prior to laying down the sleeper the concrete should be treated with a finish and a heavy moisture resistant sheet of plastic should be installed to prevent moisture from reaching the finished flooring material.