Pole Barn

I hope to build a pole barn some day but the land isn't really level there. Their might be a 12"-18" drop over 40'.

What I was thinking was sinking in all the posts then filling in to grade. But how would I keep the dirt from washing out from under the concrete slab other than fitting concrete blocks between the posts and filling them with cement.

sinking the posts, using form boards and pure some concrete in making a mini retaining wall leaving the outside form board on and using it as a lower band board ?

Doing this would allow me to fill in the floor as I can also allowing nature to help settle the fill until its enough to where I can pure a slab.

Ideas ?

If you want to pour a slab, you should really pay a few bucks to have the top soil stripped and compacted fill placed to provide a good base for your concrete. The cost to do it right really isn't that much compared to the costs you'll incur fixing problems that crop up if don't properly prepare the site.

Andy I understand what you are saying.

Tenn has good clay type soil. When dry, its like brick. Where I want to build my shop slopes down hill a little. The driveway is higher than where the shop is going to be.
Being understood the posts need to be sunk in the ground, could I pure a concrete wall incorpiating the posts to a level that would allow me to build up a good base to grade to where I them could pure the cement floor which would be about 6" above the driveway grade to keep water and such from flowing thru the garage plus I would be able to lay a grey water floor drain that would flow out the back of the shop. I am only talking about 8" in the front side to 18" in the rear.

What kind of issues would I be looking at by incorpirating the posts with the form boards and puring a small retaining wall to contain the base used to build up the flooring. The outside boards would be PT and would be left to be used asthe lower band board for the side of the building.

You can do it, but compare the costs of a properly constructed retaining wall to what it will cost to bring in fill and prepare the site. Conventional site prep using fill may be cheaper than building a retaining wall.

Take a look at the book "Post-Frame Building Handbook" put out by NRAES, Northeast Regional Agricultural Extension Service. It has good information on site preparation.

I had the same problem when adding a 20 x 30 addition to our arena, land sloped about 2 feet in 25 feet, sloping away from the arena. I brought in crushed stone as fill and prepared a level site before sinking any posts. That way you're not maneuvering around the posts while spreading the material. The site was leveled about 3 feet beyond where the walls end, then tapered down to ground level. I tamped as I went by driving back and forth with my pick up. Not as good as a vibratory roller but it worked pretty well. When we drilled for the poles we just went right through the fill. I would definitely prepare a level site FIRST, then start construction. _Letting the site sit through a few good rains doesn't hurt either, water does a pretty good job of packing things as it washes the fines down and settles.