Yep upstairs, the noise was incredible. I was about to squat so loaded 60kg onto one side of the bar and as I walked around to load up the other side, the bar tipped up, slid off the catchers and obviously thought it'd try having sex with my floor. Which it did. Successfully. Luckily it's just through the first layer of floor boards, it didn't go all the way through, that certainly would've required some fixing!
I've got matting either side of the rack where the barbell makes contact, just not everywhere else as, prior to this, I didn't really think it was necessary! It's because I'm used to training with my mate so we load the bar up simultaneously but I was on my own today and forgot about gravity.