Basically I want to know if what I’m imagining is possible. We have a staircase that goes straight up, central in the house with what I believe to be load bearing walls on both sides. There’s nothing above it and window at first floor height (impossible to reach and clean! Essentially I’d like to board across the bottom third of the staircase, and create a doorway from my son’s bedroom to give him a cupboard. This would mean making a doorway in a supporting wall and creating a floor where there isn’t one currently. Before I get a builder in for a quote and look like an idiot, do people think this can be done?