Hangzhou, it may be time to involve an outside private inspector to give his opinion on what, if any, issue there is. Backing out of the contract at this stage may cost you some money, depending on your contract. Problem could be any of the issues suggested, and it might also be "hot concrete" pour that's the issue, hard to tell.
If you need a referral for an outside inspector contact me offline. I'm also in the 94539 area code, you could also email some photos that I could forward to my inspector for comment....
Steven A. Ornellas, GRI, ABR, e-PRO, CMPS, RE Masters, MBA
REALTORÂ® / Mortgage Banker-Broker / Certified Mortgage Planning Specialist
Steven Anthony Real Estate & Financial Services
Expect Excellence. Get What You Expect.â„¢
Web Reference: http://www.Steven-Anthony.com