Chain Link Fence

[Bowfin]

So I moved to Duluth and put up a chain link fence in the late 1990's. Not ever working in clay before, I cemented in the posts like I've always did when putting in fences in sand and dirt. Over the last 15 years I have been watching random fence posts frost heave every year in the clay soil up here. I started pulling a couple posts to replace them.

Anyone have any tips how to secure chain link fence posts in clay soil without having them frost heave? I was thinking of a small bit of cement at the bottom of the hole, filling the rest with pea rock and then a small bit of cement at ground surface?

[Pat K]

If you use sona tubes you will have fewer problems with frost heaving. The freezing clay can' grab the treated cardboard as easily as it can the uneven edges of free form concrete.

[CAMAN]

Sono tubes work well, you can also flare the hole. By making the top of the hole 6-8" diameter and the bottom wider it prevents the soil from grabbing the concrete and pushing it up. Also dig the hole 3-6" deeper than needed and pour some pea gravel at the bottom to help keep water away.

[Bowfin]

I bought some sona tubes and pea gravel. Is it alright to set some posts in cement when its getting below freezing at night? Will the cement cure when lows are getting in the 20's?

[cavalierowner]

Not a problem because the concrete is getting warmth from the dirt around the Sonotubes. And concrete generates some of it's own heat from the curing process. In fact, to a point, the slower the concrete cures, the stronger it is.

[Down Deep]

I live in the Duluth area. I had a 5ft chain link fence installed 8 years ago. When I was getting bids 3 of the 4 companies were going secure the posts in concrete and one said he would drive them straight in the ground. When I asked him why he said you have clay and gravel soil and the frost will heave the concrete and post right out of the ground. Having had experience with deck supports being heaved by frost I believed him. My fence has been in the ground for 8 years and the posts are still straight, the gates open perfectly and the fence is tight and level. If it were me I would knock the concrete off or buy some new posts and drive them in.

On another note. The installer also told me that given the harsh winter weather it would be inevitable, that over time, some heave would occur no matter how fence posts are installed. He said with the post simply driven in the ground I could call his company back and reinstall the fence for the cost of labor. With concrete that option is way more expensive.

[Bowfin]

Down Deep,

I'll keep this in mind. I replaced 4 posts with sona tubes this last week but I have more to replace next summer. Maybe I'll have them driven and have an experiment going in my back yard!

Thanks everyone for your comments.