hi, We currently have a old (1970s i think) concrete panel garage (pebledash covered). We only have 1 panel sized window about half height of panel and full width. Is it ok to remove a full panel and insert a door? The frame would be made by hand by a mate (joiner) and the door of a standard size and cut down slightly. The roof then supported on 5x2" just like where the window is. so can this be done? any advise is welcome. thankyou.