I'm designing a new kitchen extension. It requires a steel beam to create an opening in a current external wall. I have designed it to be placed below the ceiling height as shown in the drawing. I want to know if it can be placed above the ceiling, at the level of the floor joists in the existing building. I thought the joists could be propped and the wall propped then the wall knocked out around the joist ends. I assume they are built into the wall. they run perpendicular to the beam. Here are some pictures of the wall. The corrugated plastic is to come away. The opening is about from window to window in this pic. Any help appreciated.