Federal Taxes: Amt Deduction Eligibility of Refinanced Mortgage Interest

I have a question on federal taxes. If I do a cash-out refinance on my main home, with less than 100% LTV, the interest on the new balance would be fully deductible under "standard" taxes. But for AMT taxes the interest on the increased balanced would be deductible only if it was used to improve the home. The question is if the home improvement expenses can be incurred prior to refinancing? In other words if I spend, say $100K to improve the home using my savings, and later refinance the mortgage later and get $100K cash out, can I claim that this increased mortgage balance was used to improve the home? I don't see any IRS publications that state this one way or another.

Federal Taxes: Amt Deduction Eligibility of Refinanced Mortgage Interest