Many properties both old and new have solid concrete floor slabs, these have both advantages and disadvantages over suspended timber floors. The main disadvantage with older concrete floors is that they can be prone to cracking and can sink or rise up if the substrate the soil or other matter below them has been either disturbed by things like tree roots or defecting water pipes and drains or have simply been constructed badly or damaged from some form of structural damage. The other disadvantage is that older floor slabs often lack both a DPM or damp proof membrane or any insulation and can act as a cold sink drawing heat from the property. It is also more of an issue if you need to retro fit pipe work or cables if you move or add items like sockets and radiators. Often these issues are raised by surveyors when a property is sold or remortgaged and they usually recommend that a structural engineer be commissioned to write a report on the possible causes and recommendations for the removal and remedial repairs to the floor slabs. It is usually recommended that the defective floor slab be replaced and a new DPM and insulation be installed. This will automatically trigger the need for a building notice and the works to be inspected at various stages by the local authority building inspector. Your building contractor should be able to take care of this for you but you should check to make sure they have the paperwork in place and the inspections booked at the appropriate time.