Additional room plans

I want to build a detached room next to my house. The room needs to be 4mt x 4mt with an ensuite bathroom approximately 4mt x 1.5mt. Shower recess needs to be at least 1500mm and a laundry tub with space for a washing machine. Floor to be tiled with underfloor heating. Front of room to face North, flat roof with high windows for light on northern side. No windows on other sides except for bathroom which needs to be on East side of the room. The existing house is to the East of the site and has flat roof facing South, This room will face North so opposing rooflines