I, and many others, wrap their cages in shower curtains. I use the inexpensive white ones so it also acts as a visual barrier. Wrapping the cage in the tarp does not defeat the purpose of the careen cage. If you were to seal all of the edges of the tarp to the cage then it would. By attaching just the corners, as I do, it still allows plenty of air exchange to take place while keeping overspray contained in the enclosure.