We learned the hard way that regardless of cage layout, the bottom of the ramp will be an area of high traffic. Our first ramps were quickly consumed by urine at the bottom, leading them to be warped and the wood to go foul. The new ramps have a thick layer of Performix Plastic Dip (think liquid latex but stronger) over the wood, with a double layer of rubber kitchen matting over it. This prevents any liquids for reaching the wood on the ramp and should last a lot longer.