I have also seen this done where the customer writes the checks for $8,000 or $9,000 regularly for cash and tells the bank/writes in memo line that it is for a contractor. The bank knows that the customer has construction being done on their home.

While the contractor may very well want cash to avoid the issue of bad checks, it is still structuring and should be reported.
Kathleen Blanchard CRCM "Kaybee"