Our current flooring is laminate and has been down for about 10 years. We thought it's time for a change and so bought some new stuff. Are there any pitfalls with putting the new flooring down on top of the old stuff. Obviously I would use an underlay for sound proofing etc. but I don't think I need to worry about underlay with a damp proof membrane because the original flooring has been down for 10 years with no problems.