The primary helical screw vendor in Marin is Chris Baumstagger (Woodacre, CA 415-488-4598); he uses AB Chance helicals. Chris is a great guy. He knows his stuff and he seems to have most of the Marin business. He provided a quote of $93,000, including all concrete work, yet this fee would not include reconnecting the house, sheet rocking, finishing, etc.  Chris was a wealth of information. He had a few specs he wanted to change on the plans, for example, instead of using sand under the slab, placed there only for curing the concrete, he was interested in using recycled concrete ground into gravel. He explained that I should describe this project as a "voluntary foundation upgrade" (which it was) to make it easier to fast-track the plans. He said he could build off the plans that the engineer had provided, and he didn't think that drilled piers were the Cadillac. In his words, "we helical guys end up repairing too many of them."

More than a year had passed since I had spoken with Chris. With the foundation project suddenly moving forward, I reached out, leaving a few phone messages saying I was ready to move on the foundation upgrade. He didn't get back. Perhaps it was because I originally spoke with him back in August of '06, and I might seem a bit flakey. But the bottom line was I needed to find other helical screw vendors.

I asked Dave Olnes, my engineer for the parking space retaining wall. He provided three names. 

I contacted George Walton, with Alameda Structural (510-301-4583). George explained that he had smaller equipment and if he could do the work it was less than 30 kips, otherwise it would have to be someone else. 

I contacted Dan Yust, at Accustruc (925-872-4680). Dan had a few comments. Could he begin at 7am since he would be driving from the East Bay? Did I plan to live in the house? (He didn't recommend it, since among other reasons, earthquake risk.) He advised that he would not suggest trying to save the pantry. It would cost $5,000 to save and perhaps $10,000 to rebuild from scratch. He thought that it would cost about $1,000 to $1,500 per helical to use him. The plan called for 13 verticals and three diagonal helicals.

Finally I contacted Tony Yudice at GeoSystems (415-456-1492). Tony Yudice came out, visited the property, and seemed like a solid guy. He quoted $23,625. He was in Marin, and seemed competent, so I approached my structural engineer to confirm that Tony's proposed Cyntech screws would be OK. The engineer agreed, under the condition that I increase the thickness of the shaft, and increase the diameter of the blades at the end. Tony explained to me that this was overkill, and that the larger blades would probably not even penetrate to the depth stipulated by the engineer, given the dense clay that the soils report indicated, but that he would order the larger screws.

Footnote: Tony was right. The screws were specked to go 20'-30'. into the ground. They went only 10'-15'. The helical portion of this foundation upgrade cost more than it should of, since I had to order hardware that was not used.