What is the best way to generate a 3D mesh from a number of planes?

I'm trying to create a 3D mesh of a room from a given a set of planes. I've managed to create a rectangular box if I take the outermost points from the intersections of the equations of the planes (as long as they're within the bounds of the box). This approach does not work for rooms that have different shapes, like for example an L-shaped room. I'm wondering what approach should I take to be able to do this for rooms of any shape? Thanks.