Deductions & credits

If an earthquake brace/bolt retrofit cost $15,000 and I received a $10,000 non-taxable/non-reportable FEMA grant, would my cost basis be the net cost to me $5,000 or does the entire $15,000 (the full value of the retrofit project) go to the cost basis?

 

I paid all the expense out of pocket, and was partially reimbursed with non-reportable FEMA grant money that is also tax exempt in California...

 

(I know the answer seems obvious, but I'd like to hear other opinions! thanks.)