Concrete – Can a conical form for pouring shorter concrete footers be used for fence posts

concretefencepost

The frost line is 1.2m deep in my area. That seems like a lot of concrete to pour for a fence post.

I'm wondering if a better way is to make a shorter footer following the suggestion that's used in wooden posts shown below, but with concrete footers:

Diagram showing conical-shaped wooden fence posts

Digging a hole like this seems tricky, so a concrete form seems like a better way. I found a patent for this kind of forms, but don't know where they can be purchased.

So, my questions:

  • Would a shallower conical post resolve the issue of frost heaving?
  • If so, how shallow? Wind load is a factor, so assuming a 2m high privacy fence, perhaps all of this is moot.
  • Where can one buy conical forms?

Best Answer

You can't escape physics and violate code, which places footing depths below frost depths. Just be glad you're not in Alberta, I hear they must go to 12ft.

Where restraint in the form of a building load is present, heaving pressures may or may not overcome the restraint, but they can be very high: 19 tons/sq ft has been measured, and a seven-story reinforced concrete frame building on a raft foundation was observed to heave more than 2 in

Concrete Network article on shallow footings and frost

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