you need to ask for a cement (powder) based flexible adhesive. you'll have to mix it yourself with water. if your tiles are white or a light colour get a white adhesive. the shop will prob try and give you a rapid set adhesive, just be careful when using rapid set as it will set really fast. you'll only get about 20-30mins bucket time. I'd advise you ask for a slow setting adhesive unless your husband is a quick tiler. goog