Continues to examine the provision of damp proofing in ground-supported floors. Considers the problems associated with dampness in and damp proofing of floors in old buildings. Examines the options for replacing the original defective floor with a ground-bearing floor. Indicates that when a new DPM is installed, moisture can be diverted from the underside of existing ground floors to the external walls. Shows that in some instances the provision of a DPM may not be essential in replacement ground floor slabs provided that certain precautions are taken.