When installing floorcoverings as part of a refurbishment, especially in older buildings, you may find a number of challenges that would be less likely to be encountered in new-build settings, including contending with subfloors in a poor condition. Among these are sand/cement or calcium sulphate screeds with a weak or friable surface – often the result of improper installation or curing techniques. Fortunately, if one of F Ball’s technical representatives has the chance to inspect these, they can often recommend steps to avoid the need to completely remove and replace them, saving considerable time and expense. This was the case when F Ball’s technical service department recently attended a school in Leicestershire to advise on installing floorcoverings in two ground-floor classrooms. AssessmentThe first room was in the original building, which predates 1965, where old 9inx9in thermoplastic vinyl tiles had been removed, leaving most of the old black bitumen adhesive behind. However, where the adhesive had lifted it revealed the sand/cement screed subfloor had broken up in places and appeared to be weak and friable. Moisture tests undertaken using a digital hygrometer indicated that subfloor relative humidity levels were 92% in this area. In accordance with BS8203 Code of practice for