I received a bid from a GC on a home addition project that seemed way too high based on my research for the foundation, but wanted to get others opinions.

The project will add 1,500 sqft, composed of three separate (but adjacent) additions to an existing home. All additions are straight forward rectangles, the lot is flat with easy access to the backyard for trucks/equipment.

The foundation is scoped as crawl space, 18" minimum code depth with poured concrete walls and footers. I am located in Contra Costa County CA.

The bid was as follows:

Demolition: $8K
Excavation: $27K
Foundation: $47K

Demo included 700 sqft of existing concrete (2" depth).

Therefore, total cost is over $80K, which seems about 4X what I thought it should cost in my area.

Thoughts? What am I missing here? (other than more bids, which I am in the process of receiving).