To create the ultimate man/woman cave, think about getting a wooden portable building. The benefits? Cheaper than a renovation, portable for when you move, insulated for a dry warm environment, and configurable to just the way you want it. Even include a kitchenette and a bathroom if required.
Space is well used and sizes for man/woman caves range from 4.8 metres x 2.4 metres up to 12 metres x 4 metres. They are pre-built ready to go on site. Similar uses for our portable buildings include workshops, work spaces, hobby spaces, and rumpus rooms.