Post Footings

I have been working on finalizing the footing plans for the twenty posts we need to put up for our barn. I have a grave concern for rising damp. The antique wood we have, and the new posts we are making out of our felled poplar trees deserve to remain dry. I have seen the damage done to those components of the barn that were in contact with ground, and the amazing preservation afforded those posts held up off the ground by a simple rock footing. The rock, having been much denser than concrete, didn't exhibit the rising capillary action of water near as much.

This capture from SketchUp shows a compound footer made up of 12 inches of compacted stone and a 36"X36"X12" concrete filled FastBag from FabForm. We will dig out 20 holes, 12 inches deep, by 36 inches square, to hold the rock, [Thank goodness for the back hoe!], compact it with a hand tamper, and set the bags over the rock. That will give us effective 2 foot deep footers with half the concrete.The bag is waterproof, and will prevent ground moisture from entering the concrete. We will place a moisture barrier under each post, likely a square of EPDM, to serve as a backup.