24x32 cabin pier question.

[Johnbenjamin]

Hello,
I'm building a 24x32 a frame cabin.  Quick question about piers.  The cabin will likely be 4' oc sitting on a tripled 2x12 "beam" supported every 8' by piers.  How small a pier can I get away with?  I was planning for 12", but 10" or 8" sonotube will decrease the amount of digging (frost line is 5').
Thanks in advance!

[Don_P]

At the bottom of that pier sits a footing that is wide enough to support the loads from above on the soils below without sinking. Think of a snowshoe, it spreads out the weight to keep you from sinking, same concept.

Building codes require piers be engineered and for good reason. You asked a question that revealed a level of understanding, but actually anyone contemplating piers should consider that to be money well spent.

[Johnbenjamin]

At the bottom of that pier sits a footing that is wide enough to support the loads from above on the soils below without sinking. Think of a snowshoe, it spreads out the weight to keep you from sinking, same concept.

Building codes require piers be engineered and for good reason. You asked a question that revealed a level of understanding, but actually anyone contemplating piers should consider that to be money well spent.

Was planning on using Bigfoot footings with the  sonotube, which will create a larger base for the pier.  Still curious which size is appropriate.

[UK4X4]

If you search the site for pier constructions the calculations have been posted many times, you have to start at the roof inc snow loads, upper floors and or lofts, main floors etc etc and then look at the total load of the house divided by the amount of piers.......

The area the piers each sit on.....and then look at the soil properties as well, as every site is diferent.

Hence engineers are commonly used.

Ball park calculations and worst case scenarios would be fine for a shed....but if your building a house then the foundation is worth investing in !

Many, me included looked at piers first and then moved on to full perimeter foundations ...or in my case a huge monolithic bath tub as my soils and location were bad.

[joebuilder111]

Question: i'm having a 16' x 36' cabin pre-built and placed on piers on a slab. The manufacturer has stated i need 30 piers under the cabin (which is built on 4x4's running the 16' direction). I'm planning on using 3 8" x 8" corner blocks. My question, do i need to mortar the piers or can i dry stack? I've attached a pic of what i'm asking. Any help would be welcomed.

[azgreg]

Why would you put piers on a slab?