Ways to collateralize funds for construction

[Pat Jackson]

I'm wanting to close on a house with cash, and borrow 30k from a friend for the repairs.  Terms:

10% interest rate, payments due at closing. Minimum of $1000 payment.  Obviously if he was loaning for purchase he could go as a first lien position at closing.  What other ways could this be formal/official and put him in position to take back the house if the deal went sideways?