I am the power of attorney for my dad. Can I use his IRA certificate and buy a new roof so Mom has one before Dad applies to Medicaid?

Find an elder law attorney. It will be worth it. They deal a lot with Medicaid.

Dallascayden: Most likely this would be allowed, but consult with an attorney to be sure.

If you father and mother live in the new house and their new house requires a new roof and you are the POA, yes, you can get estimates of best price and you can have a new roof put on the home.
This is a perfectly legitimate expense.
If you are POA hopefully you are on accounts as the signee under POA and you write out checks using your father's name, followed by your own name and the words "by POA". So it would be signed "Dad Baker by Son Baker under POA or Son Baker by POA or Son Baker, attorney in fact." You will keep this in records then in a file with Dad's expenditure.

If they are married and he l8ves in the house, this is a legitimate spend down.

I would encourage you to contact a certified elder law attorney and make sure that mom is taken care of before dad applies.

She doesn't have to live in poverty for him to qualify. An attorney can help mom keep part of dad's social security if she needs it to live.