How to build a shed ramp and account for ground heaving

Question

I live in the Baltimore Maryland area and have recently built a shed on a shed pad that is about 8 inches of 57 stone to promote drainage. I built the shed floor joists using 2x6 pressure treated wood resting on pressure treated 4x4s. My yard was pretty sloped in the back so the pad was a bit a raised off the ground in the front until I put some additional top soil down and graded. Now I need to build a shed ramp to get my small John Deere in there. I planned to remove the small green t1-11 piece under the door and add a 2x6 ledger board and use these rafter ties to add the ramp joists to the ledger board:

Where the doors open I may need to notch out a birds mouth out of the bottom of the 2x6s so the ramp hangs lower than the door and reduce the slope. At the bottom of the ramp I was going to secure the joists to some cinder blocks buried under ground with addition stone under that. My concern though is the shed, shed pad walls (where birds mouth will sit), and the bottom of ramp joists may all have ground heaving at different rates. So this could put a lot of stress on the ledger board. How could I design this without having to worry about this effect? My other idea was to not even connect the ramp to the shed and use hurricane ties and have the ramp just rest on the 4x6 shed pad walls and use the cinder block idea at the bottom still. This way it will stay close to the shed and still have something holding it still. The ground heaving issue would still be a issue though for the pad walls and the ground moving at different rates but at least the damage over time will be to the pad wall and not the shed floor joists.

Answer 1

I would suggest hanging the ramp joists off of the rim joist (use joist hangars), then leave the other end just sitting on their blocks on the ground and not attaching them to the ground.

While it is possible that the ground under the shed will move at a different rate or by a different amount than the ground under the end of the ramp 3-5 feet away, the difference isn't likely to be substantial enough to cause significant damage any time soon. Additionally, when the ground is heaving is when you'll be least likely to use the ramp for anything heavy like a riding lawn mower, so the damage will be minimal.

In a comment, you mention being concerned about the rim joist "taking all the pressure" of frost heave. The rim joist should be properly fastened to the floor joists, so any pressure on it will be distributed across all the joists that pass under the door (and several nearby). For a light structure like a shed, it's unlikely to cause significant damage in the short- to mid-term time frame.

In 20 or 30 years, you can worry about rebuilding the ramp and cursing younger you for being so lazy. :)