[Madhatter]

lintel its called a lintel, you have to acroprop the wall at the top of the opening with temporary acro props, basicaly just extending scaffolding poles that extend like a clothes prop. this holds the wall up above the opening that the joists are fixed to. The joists are the thick wooden beams that your floor boards sit on and your ceiling is screwed to. The gap between the two is often used to run cables and pipes.

I've actually heard of electricians using dogs to run under the floor boards to pull cables through.

The lintel is a steel girder that is put in to keep the wall up, its slid in and the props are taken out. Also lintels go above door openings and window openings, on older buildings they're a great big piece of stone ofeten decorative.

Must say that I'm impressed that you girls know as much as you do, do you fancy setting a building company up.