It's ceiling mounted on a beam about 2 feet from the back wall and about 2 feet clearance above it. The ceiling vaults towards the screen so the clearance is a little more at the front of the projector. The sides (where I think most of the heat is exhausted) are completely unencumbered (maybe 8 feet from one wall and 10 from the other??). That's why having some horizontal shift was important to me. I don't have a beam going down the center of the room and the screen is centered in the front. If I moved the screen, it would either block my fridge (a no no as that's where I keep beverages and food) or it would have gotten too close to the cabinets on the other side of the room. I suppose I could have spanned the beams, but didn't really want to go there unless it was unavoidable.