I'm in the middle of a riser build and everyone talks about how heavy they are, it's now more realistic. My question: this is on the second floor above a 2 car garage. The riser is in the corner of the room and house. It is 6.5x12x18. My build is pretty typical as I've used this forum for tips. Those with house construction knowledge do I have anything to worry about? I'll have 3 chairs and people at the most.