Footer Questions

[rtimgray]

Keep in mind that the bottom of the posts doesn't necessarily bear all of the weight - a great deal of the weight is borne out in the friction of the side of the posts in contact with the backfill material of the post hole. That is (more or less) how piles work - there is no "footer" per se. Poles for pole buildings also function the same way, just not as deep.

I've seen some pole building manuals recommend to NOT use a footer underneath the bottom of the pole but instead pour a concrete "necklace" around the pole (using lag bolts screwed into the pole to bond it to the concrete necklace). This increases the area in contact with the ground, increasing friction, and increasing load capacity.

So I would say that even if you think you might be marginal or below standard on the pressure for the footer area, you're probably fine by the time you add in the amount of pressure you will get from the pile friction.

Good luck and take care.

 

[Egon]

There are end bearing piles and friction piles.

Friction piles are usually driven to a refusal measurent per number of blows.

The frost area would not be considered in a friction pile.

 

[rtimgray]

The ground that is contact with a pile/post doesn't know if it was driven to refusal or if it was placed in hole and backfilled. Any area that is below the frostline will behave the same way (once settled/compacted), so you will get additional bearing capacity from the friction whether it was intended that way or not.