Floor finishes such as pitch mastic and mastic asphalt that are impermeable to water can serve as a combined damp-proof membrane and floor finish. These floor finishes should be laid to overlap the damp-proof course in the wall as illustrated in Fig. 27 to seal the joint between the concrete and the wall.
Where hot soft bitumen or coal tar pitch are used as an adhesive for wood block floor finishes the continuous layer of the impervious adhesive can serve as a waterproof membrane.
The disadvantage of impervious floor finishes and impervious adhesives for floor finishes as a damp-proof membrane are that the concrete under the floor finish and the floor finish itself will he cold underfoot and make calls on the heating system and if the old floor finish is replaced with another there may be no damp-proof membrane.
Fig. 27 Surface damp-proof menbrane.