# Concrete or Gravel Backfill for Pole Barn Posts?



## sahmoffour (Nov 4, 2010)

We're getting ready to build a 24' by 32' pole barn. We have pretty sandy soil, and aren't sure what's the best way to go about setting the posts. Dig a hole, pour in a concrete slab, place post and backfill with gravel? Crushed limestone? More concrete? Dry concrete or pre-mixed?


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## T-Bone 369 (Jan 18, 2007)

The pole barn builders I have worked with use a concrete "cookie" in the botom of the post hole then backfill with gravel. The cookie is a concrete disk about 12 inches across and five inches thick (IIRC). Seems to work out pretty well as long at the hole is below the frost line.


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## Plowpoint (May 2, 2012)

Here in Maine we never backfill with concrete because the rough texture causes the frost to "grab" the concrete, and with that 9% expansion upwards every year, tends to lift posts out of the ground. To that end, we always backfill with gravel, with the understanding that soil that has little water, does not heave as much.


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## sahmoffour (Nov 4, 2010)

Thanks, you've confirmed what I was thinking. We checked with a relative as well who's built a couple barns and they also did gravel so we'll stick with that.


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## Wellbuilt (Dec 25, 2020)

If you are in wet ground the gravel will allow water to fill up around the pole and stay wet and rot . 
I like treeted lumber 5’ from the bottom then Doug fur on the top 3 2x6 spliced add 2 12” blocks on the bottom so the pole won’t just slide out. 
Back fill with the same dirt so the water can’t collect around the pole . 
I fix a lot of real old barns and the posts rot at ground level where they get wet and then dry .


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