On Sun, 4 Aug 2013 12:11:29 -0700 (PDT), MJ
wrote:

In a week, I'll be building a 10x12 shed.

The plans call for a on-grade foundation with 6x6 skids. My property is sloped. From high pt to low pt is about 8 inches. I called out a guy and asked about pouring a slab. After I got over the price objections ($3k), he and I talked about cheaper suggestions. He said, oh, we could do Sonotube piers. I agreed but the project at that point stalled as I lost the person who was going to help.

Anyways, I found another person and he said he and I would do the foundation layout, digging, etc. ourselves. I told him my soil is kinda hard (clay and possible sandstone). No problem, just water the area and it will soften. I did a test dig yesterday and the water didn't drain for over an hour. Hmm, this is gonna be tough going.

Here's where I'm at. I could go with on-grade foundation using solid concrete blocks to level up the low spots. Not a problem for me, easy to layout and make happen. Or... we could get a power auger and drill the Sonotube piers. My helper who is a expert carpenter is away on vacation until two days before we start, so I can't get his opinion.

Which way would you go? Block or tubes?

My only concern is earth movement. Earthquakes are possibility. But a rare one. Would one would see a wood foundation come off a cement block pier in a minor (less then Richter 2) quake? I thought of drilling into the block and holding the joists with anchors. Can you drill solid block?

MJ


Here is some info on site prep. I have crushed stone
http://skipsonline.com/knowledge-base/site-preparation/

I was going to get a 10 x 12 too, but opted for a 10 x 16 and I'm glad
I did.