PLANNING First, determine whether you will be installing a three-wall unit, a sliding shower door, or both. Then you can ... While youa#39;re at the building materials retailer, select the appropriate caulking and other materials you might not have. INSTALLATION The ... In other cases, you will want to remove the old tiles and install a a#39;/4-inch underlayment panel to ensure a smooth surface. Remove old soapanbsp;...