How to handle the floor in new addition to barn.

I'm getting ready to put an addition on the side of our existing barn to use for storing hay as well as equipment.  I've got the building itself lined up with a local Amish builder, but I am on the hook for doing the floor myself.  The addition will be a "lean-to" on the side of our existing barn and will be 20 feet wide, 72 feet long and have a clearance of 15 to 16 feet inside.  The back wall and side of the addition will be enclosed, but the front will be left open for now.  I figure I can hang a tarp for the time being if I really need to.  The ground is fairly level with a slight slope towards the back of the barn and is clay soil.  I know I would like to get gravel in there for the floor, but I wanted to get the advice of all of you before I pull the trigger.  I'm thinking of getting screened gravel that is a mix of 2 inch stone on down to sand so that it will drain well, but will also pack down nicely.  Is this good or should I look at other stuff too?

 

For this winter, I'm only going to be storing some round bales and equipment in the addition and I don't think I have to have the floor in right away for that.  The round bales have been sitting on the field for just over a week, so I'm not too worried about getting the floor put in just for them.  Next summer, I plan on using this addition with my NH stacker wagon and bale grab to make haying a lot easier, so I'll definitely want the floor in by then.

 

I do have a big sheet of plastic that I bought for our greenhouse roof (supplier ended up cutting it a few feet too short) that I can use under the gravel, but if I put the gravel in now, I think it would be harder to get the plastic turned up at the sides and back of the barn when the walls go in.  The up side to this approach is that I won't have the building in my way when the gravel is delivered or when I'm getting it spread out.  The other thing that worries me about this approach is that the plastic will act like a big bucket until the building is put up and I'll have a bunch of trapped water in the gravel.

 

I could also wait and put the gravel in after the building is up, but that makes dumping and spreading it a bit more tricky.

 

Thanks in advance for all of your help.  I know this is kind of a rambling bunch of information.

 

Josh

How to handle the floor in new addition to barn.