I would provide the customer with a predictive wireless design to help with installation of a wireless network. The software I use can simulate different type of wall types and RD obstacles. I would provide the customer with a wireless coverage maps showing 2.4GHz and 5GHz coverage along with the Access Point locations and channel assignments.
I would require a .jpg or similar image of the floors you wish to cover.
Please note, that due to neighboring networks, wireless coverage could vary due to wireless interference from access points using the same channel. Unfortunately there is now way to know how much impact these neighboring networks could have on the wireless design.