D
doug boardley
in all my years tiling I've always stuck to the same principles of "never gamble" with unknown prior istallations, this principle has led to repeat work from customers plus the chain of countless recommendations. This stems from the principle of doing the job right without being hindered by cheapskate influences and "taking a gamble". The choice is yours.in all my years tiling i have done this quite a lot[tile over tile] ,ther are alot of customers out there who can not afford to have the tiles taken off and walls re~plastered,times are hard enough at the moment[or is that only in wales],as isay if the old tiles are stuck solid thre will be no problem as the weight of the tiles is evenly distributed over the full walls not just in one spot.I myself would give it a guarantee never mind the adhesive companys,so as i say imo no probs.