I have a 48" The concrete is about four feet high and the window sits on the concrete wall. I plan to remove the window and have a professional cut out the concrete opening for the door. The siding comes down about a foot below the top of the concrete wall. The question is how big an opening for the door. Being told 41.5 inches to allow for the door framing to be attached the concrete opening on both sides? How do I cover the gap where the brick mold is attached to the siding but not the concrete as the siding is over the concrete?