Modular indoor buildings create enclosed spaces inside warehouses, manufacturing plants, office buildings, and other large facilities. They allow the facilities to build out their floor plans faster and with less noise and mess than standard construction. They also can be moved and reconfigured as floor plans change. In-plant offices provide rooms for people to work. Cleanrooms and controlled environments isolate processes or equipment from the surrounding facility. Restrooms offer access to sinks and toilets. Modular indoor building accessories include windows, doors, and other optional parts for customizing modular indoor buildings.