The floor under the flooring is termed the subfloor that provides support for the flooring. Special purpose subfloors like floating floors raised floors or sprung floors is also arranged upon another underlying subfloor that provides the structural strength. Subfloors that are below grade (underground) or ground level floors in buildings while not basements usually have a concrete subfloor. Subfloors higher than grade (above ground) usually have a laminate subfloor. It takes planning from early in the designing stage and carries through even after the carpet is installed.