>>320373761
You need enough floor space to move around in for room scale VR. You can include other things within that area, like a desk or a sofa, but you'll need to be careful not to fall into it so I strongly recommend against. I made do with about 1x1 when I first got VR but it's a lot nicer now with 2x2.5. 
You can also do standing only but that's a lot more boring in my opinion.