Space & Size
Is there enough work space?
Running out of space mid-exercise is one of the most disruptive things that can happen in a workshop, and it is entirely preventable.
Space and size covers whether the room is large enough for the activities you have designed, including breakout work, wall use, movement and any physical exercises. The headcount is the starting point, but the activities are what determine the real space need. Eight people doing a collaborative mapping exercise need more room than twenty people watching a presentation.
Consider the surface area, not only the floor area. Workshop activities often need wall space for posting outputs, table space per participant for writing and building, and clear floor space for activities that involve movement or standing. A room with generous floor space but no usable wall surface is still a constraint.
Think about what the room looks like partway through the day. After several exercises, when the walls are covered in sticky notes and large paper, and tables have been pushed to the sides, will it still work? Plan the room for its end state as well as its start state.