thanks for all the replies. what I'm thinking about doing is putting in 2 5inch thick slabs of concrete over the top of my floor. thinking 2 ft in width the whole length of the lift on each side. mounting the lift on top kind of like the gas pumps islands at gas stations. I will pin the slabs in with some stainless steel doll pins ( drilling only a half inch so not to hit any water lines ) to keep it from moving and some ramp extensions for the difference in height my slab is probably more closer to 6 " thick and a 5 bag mix with fiber and wire mesh