The method involves spraying the floor's upper layer (26) with a binding retarder. The upper layer is covered with a sheet (18) as soon as the upper layer can be walked on at the beginning of the solidifying phase. Another binding retarder (22) is sprayed on before the sheet is applied. The sheet is removed between several hours and several days after the first spraying. The upper layer is then roughened by sweeping or washing. The concentration of the first binding retarder is preferably such that its penetration depth corresponds to the desired roughening depth.
