I am looking to install a fence as a DIY project. I live in the midwest where the frost line is recorded at 40 inches. I was going to dig my fence post holes 42 inches, and back-fill with tamped crush rock. I am using dog eared picketing and was going to stick it together. So I figured 4x4x8 ft posts should be suitable putting 1/3 of it in the ground sitting on tamped rock the rest of the way down. It got me thinking though, if water can get in and seep through the crush rock, will I have to worry about frost raising the post? Or is it only in the soil where heaving is a problem. Otherwise I will opt for the 10ft posts but was planning on 8ft ones to save a little money.
BTW, what type of rock is normally used for fence posts? All I read is to use crushed angular rock.. Is this the same as crushed limestone?