PSA: stack the flaps in brick pattern for the second floor, mine held 40 lbs with no tape
I built a 2 story fort in my garage last weekend using only appliance boxes and started laying the top floor flaps like bricks instead of lining them up, and it held my 40 lb nephew sitting on it. The overlapping corners spread the weight so nothing sagged, and I didn't need a single strip of tape up top. Anyone else skip tape entirely on the upper levels or am I asking for a collapse?
That brick pattern trick shows up everywhere, like how a brick wall or even a game of Jenga holds up way better than just stacking stuff in a straight line. Overlapping spreads the load so each piece leans on its neighbor instead of everything resting on one weak spot.