Question about setting posts in clay soil

My buddy who's been doing this for 20 years told me to just dig the hole and set the post, no gravel needed, because the clay would pack tight and hold it. I tried that on a job in Springfield last month, and after a heavy rain, three of the eight posts were leaning. I had to go back and pull them, put in a 6-inch gravel base for drainage, and reset them. It cost me a whole afternoon. Has anyone else found a better method for clay, or is gravel the only way to go?

3 comments

3 Comments

the_fiona9d ago

Actually had the same thing happen with gravel. Water pools on top of that layer and just makes a muddy soup. Your buddy's right, the key is packing that clay like concrete. Maybe your holes were just a bit too wide.

max_brown9d agoTop Commenter

Well, I've seen gravel work for years. That pooling issue sounds like the hole wasn't deep enough.

martin.riley9d ago

So when you say the hole wasn't deep enough, are you talking about the depth of the gravel layer itself or the whole pit? Because if the base clay isn't packed right, it doesn't matter how deep you dig, the water has nowhere to go. It just sits there and turns everything into a mess. I've seen that happen a lot where people just dump gravel in a hole and call it a day. The real work is in that base layer.