fence post depth question

[Eric_Phillips]

I am putting up a fence for some horses. I have a line about 12 posts long and 5 of them in the middle are only in the ground between 2-2.5'. They are 4x4s. I was using a post driver and hit rock. Will these be deep enough for line posts or should I pull them out and drill holes and break up the rock? Here is a link to the type of fence I am putting up 1" Ponyrail 14 Gauge 750 ft White

The top of the fence will be 54".

 

[oldnslo]

I am putting up a fence for some horses. I have a line about 12 posts long and 5 of them in the middle are only in the ground between 2-2.5'. They are 4x4s. I was using a post driver and hit rock. Will these be deep enough for line posts or should I pull them out and drill holes and break up the rock? Here is a link to the type of fence I am putting up 1" Ponyrail 14 Gauge 750 ft White

The top of the fence will be 54".

My only concern would be will the frost push these ot of the ground farther?

 

[forgeblast]

I have a set of old jackhammer bits to break through the layers of rock to set fence posts, using the bits and a sledghammer is just part of putting fences in around here. I try to get them down at least 30'' anymore and im happy but sometimes the rocks win.

 

[ToadHill]

as the frost heaves them, you'll probably have to pound them in every few years. I know around here the frost line is at about 40 inches so every thing is supposed to go down 48"

 

[Gizmo2]

My dealings on frost and fence posts (4x4) in Sullivan County NY is the frost will pull the post up rather than push it up from the bottom at 2.5 ft. The frost pulls the post up and about half the time the post will not settle back down come spring and I need to push them back down with the FEL. If we get about 6 inches of snow early on the posts will not pull up.
This fence is 24 years old with posts that were set between 2 and 3 feet....
http://www.tractorbynet.com/forums/projects/156233-board-fence-2.html#post1809077

I would also consider the rock you hit as an extension of the 4x4 post and not worry about it.

 

[Chilly807]

I wouldn't be too concerned, if it gives you problems deal with it then.

Chilly